Effectiveness of Air Filters and Air Cleaners in Allergic Respiratory Diseases

    Effectiveness of Air Filters and Air Cleaners in Allergic Respiratory Diseases


    Air filtration is frequently recommended as a component of environmental control measures for patients with allergic respiratory disease. Residential air filtration can be provided by whole house filtration via the home’s heating, ventilation, or air conditioning system, by portable room air cleaners, or a combination of the two. Appliances to filter the sleep breathing zone also have been developed. High-efficiency whole house filtration, high-efficiency particulate air sleep zone air filtration, and high-efficiency particulate air room air cleaners all appear to provide various degrees of benefit. Recent studies of various types of filtration, used alone or as part of more comprehensive environmental control measures, are reviewed.


   



    Keywords: Air cleaner, Air filter, Air filtration, Breathing zone, CADR, Clean air delivery rate, Environmental control, Furnace filter, HEPA, HVAC, Indoor air, Indoor allergens, Intervention measures, Ozone, Particulate matter, PM, Room air cleaner, Sleep breathing zone, Ventilation, Whole house filtration


   



    Environmental control practices (ECPs) are a group of measures recommended to reduce exposure to indoor allergens (eg, dust mites, household pets, cockroaches, mold, mice) or nonallergic triggers (eg, environmental tobacco smoke [ETS], wood smoke, volatile organic compounds, particulate matter [PM]) [1]. Historically, many of the common suggestions have been empiric and not based on scientific data or evidence-based clinical trials. As a better understanding of the impact of the characteristics of housing stock [2, 3] and occupants [4] on the indoor living environment has evolved, more effective measures have been identified. These may include modification of the occupant’s habits, remediation, and/or modification of the dwelling and its furnishings, structure, or ventilation, including the use of air filtration. One major drawback in many ECP studies has been the focus on a single allergen (eg, dust mites [5]) or intervention (eg, room air filtration for cat or dog allergy [6–8]). In fact, most allergic individuals have polysensitivity to multiple allergens. ECPs are therefore much more likely to be beneficial if targeted against triggers or allergens known to be problematic for the individual.


   



    In the case of filtration, little attention has been paid to variations among the various appliances themselves, and no clinical comparisons have been done between the benefits of whole house filtration (WHF) versus those of portable room air cleaners (PRACs). According to the most recent American Housing Survey, 75% of US housing units have ducted forced air heat, while 63% have ducted central air conditioning [9]. When used in combination, these ducted heating systems are termed heating, ventilation, air conditioning (HVAC) systems. HVAC systems offer the opportunity for WHF, but poorly maintained or contaminated systems may actually increase the risk of asthma and other allergic respiratory symptoms [10]. Simple forgetfulness by the occupants in replacing the filter at suggested maintenance intervals may be the most common issue. HVAC service technicians frequently find round air filter that have not been changed for years when providing repair or maintenance services [11]. Dirty filters themselves can become a source for air contamination by allergens, particularly fungal spores [12], and can then be trapped, colonized, and released downstream as the overloaded filter fails [13]. Other issues, including air bypass from poor filter fit and duct leakage, may further confound the effectiveness of filtration in HVAC systems.


   



    A barrier to proof of effectiveness for ECPs is the complexity of the gene–host–environment interactions. Expectations have been tainted by the fact that short-term drug studies of only a few weeks’ or months’ duration can show statistical effectiveness for improvement of symptoms. However, despite major advances in the drugs available for the treatment of allergy and asthma, none have been shown to arrest disease progression permanently. Improved understanding on how to avoid or reduce triggers would be expected to have this benefit. This may not occur in the short term. Observational epidemiology has already led to the recognition of a wide range of triggers found in the indoor environment, ranging from dust mite to diesel exhaust particulates. Applied epidemiologic studies are helpful in understanding targeted avoidance and prevention of disease progression.


   



    Morgan et al. [14], as part of the Inner-City Asthma Study Group, conducted a randomized controlled trial of comprehensive ECPs in 937 children with atopic asthma. All were sensitized, as demonstrated by positive skin test, to at least one indoor allergen. A baseline home evaluation included both direct visual inspections and dust collection from the child’s bedroom. Targeted ECPs were then implemented based on skin testing results and the home evaluation. Interventions included the use of a high-efficiency particulate air (HEPA) room air cleaner in the child’s bedroom if the child was exposed to ETS, sensitized and exposed to cat or dog allergens, or sensitized to mold. The intervention group reported significantly fewer symptoms of asthma during the intervention year and the follow-up year. The maximal number of days with symptoms was lower in the intervention group by 0.82 day per 2-week period in the first year (P?<?0.001) and 0.60 day per 2-week period in the second year (P?<?0.001). This effect is similar to that described in placebo-controlled studies of inhaled corticosteroids. The authors concluded that an “individualized, home-based, comprehensive environmental intervention decreases exposure to indoor allergens, and results in reduced asthma-associated morbidity.” This study and its outcomes represent the current thought that multiple ECPs, but not single interventions, are effective in modulating symptoms of allergic disease.


   



    A recent review of 3,727 adults with asthma by Roy and Wisnivesky [15], using data from the Four-State National Asthma Survey, examined the association between preventive asthma care and comprehensive ECPs. Comprehensive management was defined as the implementation of combinations of at least five of eight measures. Air filtration was found to be the fourth (27.4%) most commonly implemented strategy, preceded only by no smoking (80%), no pets (53.9%), and washing sheets in hot water (43.2%), and followed by pillow covers (23.7%), mattress covers (23.4%), no carpets (14.5%), and use of a dehumidifier (13.8%). A similar study in the pediatric population found the same rate of air filtration (27.4%) use in the households of asthmatic children [16].


   



    The role of air filtration in providing relief for individuals with allergic respiratory illness has been studied for more than 40 years [17, 18]. Prior reviews of air filtration have focused primarily on PRACs and the effect on patient symptom scores [19–21]. Reisman [19] stated that the studies should focus only on IgE-proven disease and HEPA PRACs. Wood [20] concluded that while HEPA PRACs may be an option for cat and dog allergy, there was no evidence they were effective for dust mite or mold allergy. Focusing only on allergies does not take into consideration the effects of PM and other indoor air pollutants. McDonald et al. [21] reported a meta-analysis of the only 10 randomized controlled trials on filtration published from 1973 through 1999. All 10 trials included asthmatic patients. The authors found a small statistically significant improvement in total symptoms and sleep disturbance associated with use of air cleaners, but no improvement in nasal symptoms, medication use, or peak expiratory flow (PEF) values.


   



    In a 2010 rostrum article, Sublett et al. [22??] provided a comprehensive review of air filtration. The authors described the characteristics of airborne particulates, including allergens, to be filtered, and pointed out that the impact of inhalable PM and the effect on disease is not always IgE mediated. Residential air-cleaning products and devices are categorized into two broad categories: WHF (ie, filters or cleaners that are installed on the central HVAC system) and free-standing PRACs. Current standards for testing to determine the American Society of Heating, Refrigeration, and Air-Conditioning Engineer’s (ASHRAE) minimum efficiency rating value (MERV) for furnace filters and the Association of Home Appliance Manufacturers rating system clean air delivery rate (CADR) for room air cleaners are outlined. They also described the results of 18 studies on air filtration from 1973 to 2009, including some studies previously reviewed. The authors concluded that for the “optimal choice of cleaning devices, initial cost and ease of regular maintenance should be considered. PRACs with HEPA filters, especially those that air breather filter the breathing zone during sleep, appear to be beneficial. For the millions of households with forced air HVAC systems, regular maintenance schedules and the use of high-efficiency disposable filters appear to be the best choices.” They, as had previous reviewers, recommended that more rigorous study methods be applied to future research on air filtration and that the studies be of sufficient duration to show effectiveness.


   



    Since the Wood [20] and McDonald et al. [21] reviews, there have been 14 studies (Table 1) published that are applicable to the role of air filtration as an environmental control measure for allergic respiratory diseases.


   



    Urbanization increased population density in cities and consequently leads to severe indoor air pollution. As a result of these trends, the issue of sustainable and healthy indoor environment has received increasing attention. Various air filtration techniques have been adopted to optimize indoor air quality. Air filtration technique can remove air pollutants and effectively alleviate the deterioration of indoor air quality. This paper presents a comprehensive review on the synergistic effect of different air purification technologies, air filtration theory, materials and standards. It evaluated different air filtration technologies by considering factors such as air quality improvement, filtering performance, energy and economic behaviour, thermal comfort and acoustic impact. Current research development of air filtration technologies along with their advantages, limitations and challenges are discussed. This paper aims to drive the future of air filtration technology research and development in achieving sustainable and healthy building ventilation.


   



    The most effective ways to improve your indoor air are to reduce or remove the sources of pollutants and to ventilate with clean outdoor air. In addition, research shows that filtration can be an effective supplement to source control and ventilation. Using a portable air cleaner and/or upgrading the cone air filter in your furnace or central heating, ventilation, and air-conditioning (HVAC) system can help to improve indoor air quality. Portable air cleaners, also known as air purifiers or air sanitizers, are designed to filter the air in a single room or area. Central furnace or HVAC filters are designed to filter air throughout a home. Portable air cleaners and HVAC filters can reduce indoor air pollution; however, they cannot remove all pollutants from the air.


   



    The following publications provide information on portable air cleaners and on HVAC and furnace filters commonly used in homes.


   



    Heating ventilation and air conditioning system (HVAC) is very important for offices building and human health. The combining filter method was used to reduce the air pollution indoor such as that particulate matter and gases pollution that affected in health and productivity. Using license plate frame in industrial HVAC systems (factories and manufacturing process) does not enough to remove all the indoor pollution. The main objective of this study is to investigate the impact of combination filters for particle and gases removal efficiency. The combining method is by using two filters (particulate filter pre-filter and carbon filter) to reduce particle matter and gases respectively. The purpose of this study is to use minimum efficiency reporting value (MERV filter) rating 13 and activated carbon filter (ACF) to remove indoor air pollution and controlling the air change rate to enhance the air quality and energy saving. It was concluded that the combination filter showed good removal efficiency of particle up to 90.76% and 89.25% for PM10 and PM2.5 respectively. The pressure drop across the filters was small compared with the high-efficiency filters. The filtration efficiency of combination filters after three months' was better than efficiency by the new MERV filter alone.

Recent trends and future of pharmaceutical packaging technology

    Recent trends and future of pharmaceutical packaging technology


    The pharmaceutical package market is constantly advancing and has experienced annual growth of at least five percent per annum in the past few years. The market is now reckoned to be worth over $20 billion a year. As with most other packaged goods, pharmaceuticals need reliable and speedy packaging solutions that deliver a combination of product protection, quality, tamper evidence, patient comfort and security needs. Constant innovations in the pharmaceuticals themselves such as, blow fill seal (BFS) vials, anti-counterfeit measures, plasma impulse chemical vapor deposition (PICVD) coating technology, snap off ampoules, unit dose vials, two-in-one prefilled vial design, prefilled syringes and child-resistant packs have a direct impact on the packaging. The review details several of the recent pharmaceutical packaging trends that are impacting packaging industry, and offers some predictions for the future.


   



    Packaging is defined as the collection of different components which surround the pharmaceutical raw material from the time of production until its use. Packaging pharmaceutical products is a broad, encompassing, and multi-faceted task. Packaging is responsible for providing life-saving drugs, medical devices, medical treatments, and new products like medical nutritionals (nutraceuticals) in every imaginable dosage form to deliver every type of supplement, poultice, liquid, solid, powder, suspension, or drop to people the world over. It is transparent to the end user when done well and is open to criticism from all quarters when done poorly.[1,2]


   



    Distribution of products is now more global than ever. Mass customization of packaging to permit its use in multiple markets is a topic that needs exposition and discussion. Environmental issues, including sustainability, will always be a subjective dimension to any packaging design.


   



    Packaging is an emerging science, an emerging engineering discipline, and a success contributor to pharmaceutical industries.


   



    Packaging can reside, or report through research and development (R and D), engineering, operations, purchasing, marketing, or the general administrative department of a company. For the majority of products produced in pharmaceutical industries it is probably the single largest aggregate purchase made by a company of materials critical to the protection, distribution, and sale of the product.


    Containment - The containment of the product is the most fundamental function of packaging for medicinal products. The design of high-quality packaging must take into account both the needs of the product and of the manufacturing and distribution system. This requires the packaging: not to leak, nor allow diffusion and permeation of the product, to be strong enough to hold the contents when subjected to normal handling and not to be altered by the ingredients of the formulation in its final dosage form.[3]


   



    Protection - The packaging must protect the product against all adverse external influences that may affect its quality or potency, such as light, moisture, oxygen, biological contamination, mechanical damage and counterfeiting/adulteration.


   



    Presentation and information - Packaging is also an essential source of information on medicinal products. Such information is provided by labels and package inserts for patients.


   



    Identification - The printed packs or its ancillary printed components serves the functions of providing both identity and information.


   



    Convenience - The convenience is associated with product use or administration e.g., a unit dose eye drop which both eliminates the need for preservative and reduces risks associated with cross infection, by administering only a single dose.


    Primary packaging system is the material that first envelops the product and holds it i.e., those package components and subcomponents that actually come in contact with the product, or those that may have a direct effect on the product shelf life e.g., ampoules and vials, prefilled syringes, IV containers, etc.


   



    Secondary packaging system is outside the primary packaging and used to group primary packages together e.g., cartons, boxes, shipping containers, injection trays, etc.


   



    Tertiary packaging system is used for bulk handling and shipping e.g., barrel, container, edge protectors, etc.


   



    Traditionally, the majority of medicines (51%) have been taken orally by tablets or capsules, which are either packed in blister packs (very common in Europe and Asia) or fed into plastic pharmaceutical glass bottle (especially in the USA). Powders, pastilles and liquids also make up part of the oral veterinary medicine intake. However, other methods for taking medicines are now being more widely used. These include parentral or intravenous (29%), inhalation (17%), and transdermal (3%) methods.


   



    These changes have made a big impact on the packaging industry and there is an increasing need to provide tailored, individual packaging solutions, which guarantee the effectiveness of medicines.[4]


   



    The present review article details several key trends that are impacting packaging industry, and offers some predictions for the future packaging encompassing solid oral dosage forms and injectables.


   



    Aseptic blow-fill-seal (BFS) technology is the process by which plastic containers are formed, filled with sterile filtered product and sealed in an uninterrupted sequence of operations within the controlled sterile environment of a single machine.[5,6]


   



    The blow-fill-seal process is a robust, advanced aseptic processing technology, recognized by worldwide regulatory authorities for its inherent operational advantages over conventional aseptic production. Blow-fill-seal systems offer a unique combination of flexibility in packaging design, low operating cost and a high degree of sterility assurance. The machines require a minimum number of operating personnel and have a relatively small space requirement.


   



    A variety of polymers may be used in the process, low and high-density polyethylene and polypropylene being the most popular. The innate ability to form the container/closure during the actual aseptic packaging process allows for custom design of the container to meet the specific needs of the application. This flexibility not only improves container ease of use, but provides a means of interfacing with many of today's emerging drug delivery technologies, most notably in the field of respiratory therapy.


   



    Thermoplastic is continuously extruded in a tubular shape [Figure 1a]. When the tube reaches the correct length, the mold closes and the parison is cut [Figure 1b]. The bottom of the parison is pinched closed and the top is held in place with a set of holding jaws. The mold is then transferred to a position under the filling station.


   



    The nozzle assembly lowers into the parison until the nozzles form a seal with the neck of the mold [Figure 1c]. Container formation is completed by applying a vacuum on the mold-side of the container and blowing sterile filtered air into the interior of the container. The patented electronic fill system delivers a precise dosage of product into the container. The nozzles then retract into their original position.


   



    Container sealing


    Following completion of the filling process, the top of the container remains semi-molten. Separate seal molds close to form the top and hermetically seal the container [Figure 1d]. The mold opens and the container is then conveyed out of the machine [Figure 1e].


   



    The cycle is then repeated to produce another filled container. The filled containers are tested and checked to ensure that they meet the very strict specifications laid down for such products.


   



    The duration of the complete cycle is between 10-18 seconds, depending on the container design and the amount of liquid to be filled.


   



    BFS technology offers considerable advantages over conventional aseptic filling of preformed (plastic or other) containers, which are described as follows:


   



    BFS technology reduces personnel intervention making it a more robust method for the aseptic preparation of saccharin sodium.


   



    There is no need to purchase and stock a range of prefabricated containers and their closures. Bulk containers of plastic are required.


   



    Cleaning and sterilization of prefabricated containers and closures is not required. A clean, sterile container is made within the BFS machine as it is required for filling.


   



    The cost of material transport, storage and inventory control is reduced.


   



    Validation requirements are reduced.


   



    The technology allows the design of high-quality, custom-designed containers with tamper-evident closures in a variety of shapes and sizes.


   



    There is a large choice of neck and opening device shapes.


   



    A single compact BFS machine takes the place of several conventional machines, saving floor space. In addition, zones for transport to successive filling and closing procedures are not required because these operations all take place in the BFS machine itself.


   



    The operation of BFS machines is less labor intensive than conventional aseptic filling.


   



    The code numbers and variable data such as batch number and expiry date can be molded into the container itself rather than being added at a subsequent stage.


   



    The process lends itself to the production of single dose containers and therefore preservatives are not necessary as they are with multi-dose containers.


   



    Blow-fill-seal technology has gained much market focus in recent years due to the increased focus on biologics, proteins and other complex solutions. These important products often cannot withstand exposure to high temperatures for extended periods of time without degradation of their active components. Conventional terminal sterilization, therefore, is not an acceptable method to produce a ‘sterile’ product. Bulk sterilization, sterilization by gamma irradiation or filter sterilization followed by direct packaging utilizing the blow-fill-seal process are often used successfully for these types of products.


   



    Counterfeiting means producing products and packaging similar to the originals and selling the fake as authentic products. Counterfeit is a problem of product security, with reference to packaging is not a problem in isolation; it is the part along with:


   



    Duplication - i.e., copying labels, packaging, products, instructions and usage information,


   



    Substitution - placing inferior products in authentic or reused packaging,


   



    Tampering - by altering packages/labels and using spiked, pilfered, or stolen goods in place as real,


   



    Returns and Warranty frauds they are addressed as Brand Theft.


   



    The current numbers of anti-counterfeiting solutions are many and new options are introduced in the market with some variations. An attempt is made to explain the technologies for easy understanding on product packaging.


   



    1. Overt (visible) features


    Overt features are intended to enable end users to verify the authenticity of a pack. Such features will normally be prominently visible, and difficult or expensive to reproduce. They also require utmost security in supply, handling and disposal procedures to avoid unauthorized diversion. They are designed to be applied in such a way that they cannot be reused or removed without being defaced or causing damage to the pack for this reason an overt device might be incorporated within a tamper evident feature for added security.


   



    Tamper evident packaging systems


    Some packages are inherently tamper proof, like a tin can hermetically sealed, an aseptically packed multilayer carton or a vacuum or the retort pack. The tamper evident packaging systems are:


   



    a) Film wrappers


    A transparent film with a distinctive design is wrapped securely around a product or product container. The film must be cut or torn to open the container and remove the product. Substrates options include ultra destructible films, voidable films that provides image when removed. e.g., Solvent sensitive papers.


   



    b) Shrink seals and bands


    Bands or wrappers with a distinctive design are shrunk by heat or drying to seal the cap and container union. The seal must be cut or torn to remove the product.


   



    c) Breakable caps


    Such caps break when an attempt is made to open it. These caps provide external tamper evidence and can also be combined with the internal seals thereby providing double security.


   



    d) Sealed tubes


    The mouth of the tube is sealed, and the seal must be punctured to obtain the product.


   



    2. Covert (hidden) features


    The purpose of a covert feature is to enable the brand owner to identify counterfeited product. The general public will not be aware of its presence nor have the means to verify it. A covert feature should not be easy to detect or copy without specialist knowledge, and their details must be controlled on a “need to know” basis. If compromised or publicized, most covert features will lose some if not all of their security value [Figure 2].


   



    Radio frequency identification (RFID) is hardly a new concept. For some, RFID is already a mainstream technology-it is used every day to pay tolls, secure building access, catch shop lifters etc., It allows the identification of objects through a wireless communications in a fixed frequency band. Three essential components in any RFID system are: the tag, the reader and the software. The tag is an integrated circuit containing a unique tracking identifier, called an electronic product code (EPC), which is transmitted via E.M. waves in the radio spectrum. The reader captures the transmitted signal and provides the network connectivity between tag data and the system software. The software can be tailor made for the purpose of anti-counterfeiting. For their track and trace usage, RFID tags are used [Figure 3].


   



    When RFID tag is within the interrogation zone of the reader (i.e., interrogator) equipment; sufficient power is extracted from the interrogator to power up the tag or circuit, or a special reflective material. It then responds by transmitting data back to the interrogator.


   



    b) Active tag


    Such tags incorporate a battery to increase range for collating data, tag to tag communication, etc., But these are much more expensive.


   



    c) Semi-active tag


    In these tags batteries are used to back up the memory and data, but not to boost the range. With some active RFID tags, the batteries are only used when interrogated or when sending a homing pulse at fixed intervals to reduce cost and size.


   



    4. Packaging designs: Materials/Substrates and other design options


    a) Substrates


    There are variety of substrates used in the design of packages with intent to provide counterfeit and tamper evident features starting from litho paper, polystyrenes, destructive vinyl's, acetate films synthetic paper and coatings etc., There are many ways of incorporating covert markers within a substrate, such as visible or UV fluorescing fibers, or chemical reagents in carton board or paper. Watermarks can be embedded in leaflet paper, or metallic threads interwoven in the base material, possibly including an overt optically variable devices (OVD) feature. These require a dedicated supply source and large volume production, which, if affordable, results in a very effective option. Micro-encapsulated distinctive odors can be applied as an additive to an ink or coating to provide a novel covert or semi-overt feature, as well as sound chips creates special opportunities in the design.


   



    b) Packaging designs


    Packaging designs like sealed cartons, aerosol containers have inherent strength against counterfeiting


   



    c) Sealing systems


    Special caps such as the outer tamper evident system or the foil seal as an internal tamper evident feature are commonly used for pharmaceutical products. Sealing options are lever-lidded tins, secure packaging tapes, lined cartons and tear tapes/bands.


   



    5. Security labels


    Tamper evident and security labels play an important role in providing some relief to the consumers against fakes. In self adhesive labels the substrate mostly performs as a complimentary interaction of the substrate and the pressure sensitive adhesive. While passive security labels have been extensively used, today one can find a greater application of functional labels such as printing plus anti-theft. Some label options are:


   



    a) Paper labels with security cuts


    The substrate used for these labels is ordinary coated/uncoated paper. The security features are built in by the label printer at the converting stage. With the help of a special cutting die, the face material is given cuts at various angles so that by any ways one tries to remove these labels the paper will tear off. A general purpose permanent adhesive works fine with such labels. Care is taken to ensure that the adhesive will adhere well and firmly to the surface on which the label has to be applied.


   



    b) Destructible labels


    Needs a special substrate designed for the purpose. Most of the high-end applications use a specially made cellulose acetate film. The film is very intricately designed so that it has adequate strength to undergo conversion into label stocks in roll form. It is available both in clear and opaque formats and further converted into labels using aggressive pressure sensitive adhesives. The labels can be automatically dispensed on automatic label dispensers and when attempted to be removed, break-up into very small fragmented pieces. The cost effective vinyl have replaced acetate film. A combination of various synthetic polymers can be used to impart low inherent strength to the substrate.


   



    c) Void labels and tapes


    The most important of the tamper evident security labels and have text built into them. When as a self adhesive label they are removed, they exhibit the word VOID both in the removed film and the adhesive layer left behind. These substrates gain importance as there can be customization built into the labels produced with it. One can use polyester or biaxially-oriented polypropylene (BOPP) as face materials. Variety of colors, even metallization is possible. The text VOID could be replaced by the customers brand, emblem or a message, which would normally be invisible till the label is opened. Due to the versatility of things that can be done with the product, these label substrates have found widespread usage worldwide. The substrates can even be designed to work as tapes for the final outer corrugated cartons to prevent pilferage.


   



    d) Self destructing paper label


    The labels are very similar to destructible labels as mentioned earlier. In this case, the substrate used is of very weak strength paper of low grammage. The paper is also heavily loaded with fillers creating a weak and brittle paper. Labels made from such papers fragment into pieces when attempted to be removed. However, converting it is a very tricky issue when using these substrates due to the lack of strength. The papers are very difficult to source since most of the paper mills are trying to develop papers with very high strength.


   



    e) Holographic labels


    The labels form a very large and important part of the security label market and are an ideal choice for product authentication. The holographic foil that is an optically variable device is largely made using a polyester film base. The optical interaction of the holographic image and the human eye makes it ideal for brand promotion and security. These products reveal the holographic image when tilted in light. The image so revealed can be customized to the need of the brand owners to make the maximum impact. The hologram production involves development of complex origination process and a lot of innovation to make it difficult for counterfeiters to duplicate. Many holograms are designed such that besides offering brand authentication they also have tamper evident properties. The top polyester layer has a special coating that if the hologram is attempted to be removed, the top layer peels off leaving the hologram behind on the product [Figure 4].

ULTIMATE GUIDE: BEST SOFT CLOSE DRAWER SLIDES

    ULTIMATE GUIDE: BEST SOFT CLOSE DRAWER SLIDES


    The best soft close drawer slides will open easily, close smoothly and be certified for durability. But unfortunately finding a brand name slide that works properly isn’t easy. And, since soft close slides require precision installation, there are a few tools you MUST purchase for proper installation. In this article learn what the best drawer slides are for your projects – and what you need to install them.


   



    First, after building and installing over a thousand drawers, I know drawer slides must be durable and reliable.


   



    First up is understanding what a soft close drawer slide is – and isn’t.


   



    So, as you’d expect, a soft close drawer slide does two things. First, it prevents drawers from slamming through use of a damper that catches the drawer and slows the closing force. Then second, using (preferably) two large springs the soft close mechanism gently pulls the drawer closed.


   



    Is it the same as self closing? No.&nbsp;


   



    But will a quality soft close drawer slide keep most drawers closed? Yes.&nbsp;


   



    BEST DRAWER SLIDES FOR CABINETS AND FURNITURE


    As with a lot of hardware, there just isn’t a great variety of choices.


   



    While some top brands like Accuride dominate in self closing under mount slides(that are not soft closing!), they just didn’t perform as well as others.


   



    So, based on my reviews and use, here are the top three choices for your next project.


   



    There’s a reason most cabinets offer undermounts as upgrades: they simply perform better.


   



    Because an undermount drawer slide places the weight of the drawer on horizontal rollers (versus steel ball bearings) the drawer action is SMOOTHER.&nbsp;


   



    For example, the Blum 563H won’t require the hard pull to open like you’d find in a low quality side mount soft close slide. And, since they aren’t metal-on-metal, you’ll find they are quieter as well.


   



    So what’s the catch? You’ll need to make a few custom measurements as these slides don’t use a standard 1/2″ side clearance. Instead, you’ll have a slightly wider drawer and require an extra 1/4″ or so clearance under the drawer to fit the slide.


   



    I was surprised with this drawer slide.


   



    First, they come individually or in packs of 2, 6 and 10 at half the price of most other drawer slides.&nbsp;


   



    And, while they what I consider a “generic” slide as they aren’t from one of the established manufacturers, their construction was TOP NOTCH when stacked up against the other slides.


   



    And, in a brand test, I’ve put these ahead of the well known Accuride as they simply performed better and were surprisingly quieter when opened and closed. As you know, or don’t, that will matter when you first open and close the door as a “clicking and clacking” sound is one of the hallmarks of poor performing ball bearing slides (soft close or standard).&nbsp;


   



    Lastly, with their great bundled price, I’ve also installed these in a recent garage workshop makeover. And after loading one drawer (~15″ x 22″) to capacity with heavy screw boxes it has performed fantastic. I’ve even attempted to slam the drawer and it’s damper has worked each time.&nbsp;


   



    And the Accuride C-3832 drawer slide is a strong competitor.


   



    However, due to price and noise it falls to #4 on the list as it’s performance doesn’t stand out from the competitors to justify it’s hefty price tag.


   



    Curiously, this slide had the #1 issue with side mount ball bearing slides: it opened loud. While most high quality slides have extra “bumpers” to ensure 3 tracks don’t do this my test showed a louder than average click.


   



    However, if you’re an Accuride fan, and want to purchase slides from an industry name, then these slides are something to consider.


   



    For a brand name drawer slide with an industry reputation the Knape & Vogt are an option to the Vadania drawer slides but fall short on closing force. Due to a thinner design (7/16″), single spring design, shorter rail, and among the lowest closing force of all slides I don’t recommend this slide.


   



    &nbsp;


    Unfortunately, this slide attempted a different soft closing mechanism with a single spring and it just didn’t compare head-to-head to the other slides. For that reason, when searching for the best soft close drawer slides I’d pass on the 8400P.


    &nbsp;


    I am a fan, however, of the Knape and Vogt TruTrac slides for standard duty ball bearing without soft close.


   



    I was expecting great things from these slides but was disappointed. Due to a sloppy rail when opening and the loudest closing noise these slides just didn’t measure up to the others on this list.


   



    The Promark rear mounting brackets, however, were excellent and worked on all the slides I tested. And I particularly liked the extra wide rear width for easy screw hole access.


   



    I know you want to get to the drawer slides.


   



    But, before we do I want to share a few tips on what else to buy.&nbsp;


   



    Or, no matter how good the slide is won’t operate correctly, it might fail later, or you may possibly break it during installation:


   



    Drawer slide jigs are a must to properly align your drawers during installation. Most cost less than 1-2 pairs of slides and the Kreg KHI-SLIDE is most popular.


   



    Rear mount brackets are a must for face frame applications as they make installation faster and improve drawer performance with infinite adjustment. I’ve used the ProMark and Lontan and prefer the ProMark as it has a larger rear screw plate.


   



    Drawer screws sent by most manufacturers are inadequate. So, I use Rok #8 truss head screws in both drawer European slides and soft close cabinet hinges as they have a superior hold.&nbsp;


   



    So, add these 3 to your shopping list and you’ll experience a MUCH SMOOTHER installation.


    Don’t want hardware on the front of your drawers?&nbsp;


   



    Well, you’re in luck if you have a frameless design to your cabinets. By adding push to close to an undermount soft close drawer slide you can gently push the drawer front and the drawer will glide partly open.


   



    While these aren’t cheap, you can factor in the savings of not having to purchase additional hardware (and install them).


   



    Who makes these? A few options:


   



    King under mount push to open slides that have this feature built-in


    Blum TIP-ON is an accessory to their TANDEM slides that can be added to any compatible drawer to upgrade to push to open.


    Heavy Duty Undermount Soft Close Drawer Slides


    While heavy duty drawer slides, for me, start around 150 pounds there are a few options for soft close drawer slides at 125 pounds:


   



    Blum heavy duty under mount with 125 pound capacity


    SOFT CLOSE DRAWER SLIDE RATINGS


    We’ll go through each drawer slide in detail, but after my testing I ranked the slides as follows. A few aren’t easy to find, so I’ve included links for buying now – and most are most economical in a 6 or 10-pack (just divide by quantity to get per unit).


   



    Lastly, don’t forget rear mounting brackets, screws and a drawer slide jig when installing these soft close drawer slides


    Drawer slides can be as easy or as hard as you allow them, and it all depends on what type of slide you choose. In this guide we are going to cover the many different types of Drawer slides on the market, the many different ways a slide can be fitted into a cabinet, and then some help tips for you to decide which is the ideal type you need for your application.&nbsp; &nbsp;This is allot to cover especially when you consider that a drawer slide should be a very simple device to buy and install, but the reality is there are allot of external factors you must consider.&nbsp;


   



    Different types of Drawer Slide


    Drawer slides, or as they are sometimes called a drawer rollers, are a type of mechanism that allows smooth linear motion in one axis. They are most commonly used in pairs and found in a huge range of applications, mostly kitchen cabinets. Drawer slides generally work by having one component to slide over a slightly larger or smaller component of equal shape with roller bearings between them to create the smooth rolling function, which allows the entire mechanism to extend or retract. Drawer slides are not motorized but can be if&nbsp; a linear actuator is attached to provide the hands free motion for you. Generally, you will use drawer slides on their own and will likely encounter only two main types: Ball-Bearing Slides & Roller Slides.


   



    Roller slides consists of two components, the sliding main member strut and the fixed cabinet drawer strut. These types of slides are not fixed together until after you have attached them to both the drawer and the fixed cabinet.&nbsp; Only then can you slide the drawer into position and they then slide in and out freely.&nbsp;


   



    Each strut having one wheel attached at each end is what allows the slides to run freely but it has its limitations.&nbsp; Having only onw wheel to carry the load is a huge disadvantage. This means that the load carried by the entire drawer and its contents is all focused onto the one wheel at either side of the cabinet drawer. This point load can be large for cabinets that need to carry more load and will eventually result in failure.&nbsp; &nbsp;Another thing to note is that the plastic wheels are not mounted onto bearings, they are simply plastic wheels on a metal axel that will eventually cause noise or wear problems at some point during its lifetime. One main advantage of these is that they are very cheap to purchase from any hardware store.


   



    17mm ball bearing slides as you can see from the image above are completely different to Roller slides. These make use of ball bearings encased in a bearing cage so they don't fall out, and some models offer a telescopic motion. By telescopic we mean that the Rails have 3 or more members that once combined together are able to extend the same distance or more than their total closed length. This great use of space is what gives them such a great appeal because the drawers are then able to slide out 100% of the drawers depth in a cabinet, where-as using a roller slide you can typically only achieve around 75% opening.&nbsp;


   



    These types of slide rails offer extreme rigidity of the draw when fully opened or closed and allows them to carry a significant amount of weight. Plus the are easy to install as they have many hole patterns pre drilled along the length of each member for attaching them to both the fixed cabinet and the cabinet drawer. To open the the slides so that they can be installed simply press the lever down to unlock the full extended opening. Please view the video further down this article to see how to do that. Please note however not all Drawer slides come with the lever feature to take apart the drawer slides, all FIRGELLI drawer slides do have this feature however.&nbsp;


   



    Ball-bearing drawer slides provide a huge durability life span and have much larger load rating compared to roller slides. Within our range of Ball Bearing slides we do even offer a very heavy duty type. Click here to view them.&nbsp; Heavy duty versions of ball-bearing slides&nbsp;

How to Choose A Kitchen Faucet

    How to Choose A Kitchen Faucet


    The sink and faucet area is one of the most-used in any kitchen, and are often treated as a design focal point for the room. Upgrading your kitchen faucet is an easy and economical way to give your space a quick design refresh, or complement a whole kitchen transformation. A new faucet changes the look of the whole space. Be smart about the choice so that you find the best fit for your home and know what to look for before you buy.


   



    It’s no surprise that the kitchen faucet is one of the most well used items in the room, but what might be news is how many improvements have been made to this simple fixture. There are many more options than just the selection of comfortable handles for the hot and cold water lines. It’s a good idea to explore the different styles, finishes, and features that are available when selecting a new faucet. The right design will look great for years, and add to the value of your home - all while meeting the demands of your busy kitchen. Take a broader view of what the options are and bring home the best fit.


   



    Before you shop, it’s helpful to have an idea of what you want the end result to look like. Take stock of the styles and colors you want to emphasize and accent in your kitchen, as well as the size of your sink and countertop to compare as you consider a new faucet. The most important part about choosing a new faucet is that you be happy with the new addition to your kitchen after the installation, so always keep the final product in mind as you browse.


   



    Grab the measuring tape, because it’s time to get some numbers. It’s usually easier to find a faucet that works in the space allowed than it would be to rebuild the kitchen to accommodate a faucet. As with all home improvement projects, picking a new faucet requires some educated placement decisions, a general idea of what you want the finished sink area to look like, and the scope of the tasks it will be used for.


   



    This means you should know how wide and deep the basin is, especially in comparison to the size of plates, pots, and pans you plan to wash in the sink. Any faucet you buy will need to have a high enough spout for these chores and others, as well as a low enough placement to avoid excess splashing that will make a mess outside of the sink.


   



    Similarly, if you are looking at a deck-mounted faucet, know how much room is available behind the sink to install the faucet. A wall-mounted faucet needs to be placed with the spout extending over the center of the sink, which requires taking into account the space between the interior edge of the sink and the wall. For that, you will compare the sink measurements to the size of the faucets as you narrow down the selection.


   



    Measure the countertop behind the sink, and the diameter of the pre-drilled holes and the distance between their centers. You will need to know the width of the sink as well as the depth between the wall and sink edge. This is important for both the installation and the regular use of your faucet, as you’ll need to be sure there is room between the wall and faucet to fully articulate the faucet handles or levers.


   



    As you search for a new kitchen faucet, you’ll see a number of other options to choose from that influence the overall style and operation of the faucet in your home. It’s a good idea to understand the basic configurations before you choose, to be aware of the product information and ensure you get exactly the features you want.


   



    In a counter- or deck-mounted installation, drinking faucets can be mounted on the counter or sink edge. Deck mounted is the more common style, and it helps draw attention to the sink as a design element in your kitchen. Here you’ll find the largest variety of faucets, ranging from single-hole mounts to up to three-hole mounts, in all sizes and finishes.


   



    Wall mounted kitchen faucets are often found in more commercial or industrial locations, with a unique and modern style. Home kitchens, laundry rooms, garages, and greenhouses often rely on wall-mounted faucets for their space-saving design. In smaller kitchens with limited counter space, wall mounted faucets free up the counter and allow different design options for the sink, and unique plumbing profile lines.


   



    Valves regulate water flow and temperature from the faucets. They’re the basic control inside the faucet body that makes the water pour from the spout and aerator, turning on or off at your command with the turn of a handle. The different valve types work differently, which changes the capabilities of the design, and it also means that they require different kinds of maintenance over the long term. The valve type often describes the basic operation of the faucet, naming the moving parts that stop the water from leaking. There are many types, but there are four that are more common to come across.


   



    Ball valve - A ball valve is recognized by the single handle near the base that can control the water flow and the water temperature by pivoting and rotating to blend the water as needed.


    Disk valve - A ceramic disk valve faucet handle can move up and down to control the flow of the water, and side to side to control the amount of hot or cold in the mix. It gets the name from the two flat disks inside the faucet mechanisms that create the seal to control the water flow; moving the handle will separate the disks and allow the water through to the spigot. The disk valve can be replaced without replacing the entire faucet.


    Cartridge valve - Cartridge valves are hollow valves that are often found in faucets with blade handles because they only need turned to as much as a 90-degree angle to work. The cartridge rotates to block the water line to the spout. For a single handle faucet, the cartridge moving up and down will allow the water flow, and turning the handle left to right will control the temperature. When there are separate handles, such as in a three or four hole sink set up, two individual handles can control the hot and cold water lines separately to mix in the faucet. Cartridges can be replaced without needing to replace the entire faucet.


    Compression valve - A compression valve is usually found in older fixture styles. They look like the traditional faucet, with the 360 degree, turn-screw, knob handles. Hot and cold water are managed by separate handles, and in more vintage set ups, they can be routed to different taps as well. Turning the handles will tighten or loosen an internal washer, and that compression closes the water line. Because of how they are built, a busted compression valve will often require replacing the whole faucet rather than a few internal pieces.&nbsp;&nbsp;


   



    If your sink is a drop-in, undermount, or farmhouse design, it is likely to have a set of holes drilled or pre-punched into the deck for the faucet and other plumbing fixtures. The faucet itself can take up as many as 3 holes, depending on the type of faucet you choose, and other fixtures like soap dispensers can be installed for your convenience, too. Whether you will choose one hole, two, or even four holes along the sink deck depends on the kind of look or style that you want as much as the kind of faucet you choose.


   



    Single-hole faucet with a pull-down sprayer - These can include the high, gooseneck faucets with the tall, drastic arch leading to the spout, as well as the more industrial-style pre-rinse faucet with the durable springs and lever handle along the spray-hose for added reach and control. Others mount the handle on the faucet body, while touchless models require no handle at all; just wave at the side-mounted sensor, or for tomorrow’s kitchens, give a voice command to start up the water.


    Single-hole faucet with a side-spray - While it may be a single hole faucet, the smaller side spray will occupy a second hole pre-drilled in the sink deck or countertop. This is a simple, clean look that doesn’t take up too much extra room on the deck and offers versatility and utility. Two-hole escutcheon plates are available to accent the design, or to cover up a third hole in the sink that might not be needed.


   



    Two-handle faucet (3-hole layout) - To emphasize the artistic design of a faucet, some fixtures will have hot and cold water as separate handles, one on each side of the center faucet. It visually helps take up a little extra space along the sink edge and draws attention as a design focal point. They are also very easy to use while doing the usual sink-based chores, with one-handed hot or cold water at the turn of a handle. An escutcheon plate cover can also be utilized cover one of three holes, to allow a faucet with a single, separate control handle.


    Bridge faucet with side spray (4-hole layout) - A bridge faucet will have two temperature handles alongside a center water flow pipe. The hot and cold water will travel up their dedicated handles and then mix in the connection between them on the way to the spout. A bridge faucet can take up three holes or two, depending on the style you choose, and will usually require a separate side spray as the bridge connection prevents the extending hose feature.


   



    There isn’t much to be done with a stainless sink faucet; the entire purpose of it is as a water source, and the water is either on or off, right? Not exactly. The shape of the faucet changes from one design to another, and companies like Moen, Delta, Brizo, and Kohler are constantly looking to improve how the kitchen faucet interacts in the home. It started with the basics, like the side spray and the pull-down faucet. Now, technology-savvy companies have even wondered: why should you have to dirty up the finish with soapy fingerprints when waving a plate under the faucet could turn the water on? And their ideas and solutions improve year after year, all to make the kitchen life a little easier with a wide variety of standard features to choose from.


   



    Side sprayer - A classic staple at the kitchen sink was the side sprayer. The smaller faucet is located at the end of an extendable hose, offering directed water pressure exactly where it is needed, whether cleaning the pots and pans, scrubbing the sink, or watering a potted plant.


    Pull-out faucet - The pullout faucet offers all the convenience of the side sprayer without taking up any extra space on the sink edge. The hose extends down toward the sink or at an angle just above it, which adds a slight advantage in reach.


   



    Electronic faucet features - A growing trend in today’s homes is the addition of smart technology, computerized mechanics that help make the everyday chores a little easier. The kitchen sink can now be turned on and off with the wave of a hand thanks to motion sensor technology installed in the faucet body. Other designs include the ability to control the sink by talking to it, taking hands-free activation a step further with voice-activation. Electronic features are safe and convenient, but they may require professional installation. Sinks with electronic features will need to be installed with access to a reliable power supply, so keep their placement in mind during your kitchen remodel plans.


   



    Water filtering - Some kitchen faucets are available with built-in filtration options that can purify your tap water to make it drinkable, right from the faucet. These high-capacity faucets are capable of delivering as much as 1GPM of water, filtering out common problem chemicals like chlorine, lead, mercury, and even pesticides and pharmaceuticals.


    Drinking water dispensers - Whether filtered and cold, or ready for cocoa or tea, dedicated drinking water dispensers can be installed at the sink. They are sized to fit in the same holes that a regular kitchen faucet would use, but they are designed to pour water at a slower rate, more appropriate for filling drinking cups. They are usually found as part of a filter kit, and many include hot water dispensers that store and maintain water at a drinkable temperature just right for tea.


   



    Finally, one of the most important details when selecting a brushed stainless kitchen faucet is choosing the perfect finish. The finish determines the color and durability of the faucet for years to come. From stainless steel, to copper, to modern black, the finish can be found in a variety of metals and colors to coordinate with the accenting colors of your kitchen hardware and appliances. Newer finishes are designed specifically to resist the oils of fingerprints and smudges, making it easier to keep clean and helping to keep your family healthy. As it turns out, it’s even okay to mix metals in your home decor, so go with the style that you like.


   



    Chrome is currently one of the most popular finishes because of its versatility. It is durable, easy to find, and easy to match with accessories and other fixtures.


    A brushed nickel finish is very durable, keeping its finish longer and resisting wear and tear.


    Copper finishes provide a bold and rich feel to your space. With the ability to ‘heal itself’, the more it gets used, the better it looks.


    If you’re looking for a good balance of durability and style, you can’t go wrong with stainless steel.


    At the end of the day, make sure you pick a faucet that works with your style. While some finishes tend to be more durable than others, on the whole, most finishes will stand the test of every-day wear and tear. So really focus on style here, and find something that matches your space.

How Padlocks Work

    How Padlocks Work


    Learn about the standard iron padlock to understand the main parts, how they work and also how to bypass the mechanical security features to pick the lock.


   



    With thanks to Squarespace for sponsoring this article. Go to Squarespace.com for a free trial and when you’re ready to launch, go to http://squarespace.com/engineeringmin… and add code “ENGINEERINGMINDSET” at checkout to save 10% off your first purchase of a website or domain.


    Padlocks come in many shapes colours and sizes. They have been around for hundreds of years, ranging in complexity of design by different people and civilisations depending on the technology and manufacturing processes they had available. With the industrial revolution came the mass-produced padlock which eventually settled on a pin tumbler design. Called so because inside are some pins and a barrel which rotates or tumbles over.


   



    These are strong mechanical locks which are easy to mass produce and we find them used for everything from keeping our bikes where we left them to symbolising the everlasting love between two people on a bridge, and then throwing the key away to ensure it can’t be undone. But these types of locks, especially the cheap ones, can be unlocked without a key if you know the correct method and once we understand how the lock works we’ll learn how to pick the lock.


   



    When we look at a padlock the most noticeable feature is the U-shaped shackle at the top. In the unlocked position, one end of the shackle pops out of the main body allowing this component to rotate freely. On the inside surface of the shackle we will find two notches. These form part of the lock mechanism and we’ll see that part shortly.


    To lock the brass padlock we simply align the end of the shackle with the hole in the lock body and push these together. You’ll feel the internal locking mechanism engage and click into place, the shackle will now be unable to leave the body of the lock. To unlock the padlock we need to insert the correct key into the key hole at the bottom of the lock body, and rotate the key until it releases the shackle.


   



    When the key is turned, the plug will rotate. The plug has a number of holes in the top, within each hole there is a small metal cylinder known as a key pin. Each key pin is a different height, and this will correspond to the profile of the key.


   



    When a key is inserted into the lock, the key pins will follow the profile of the key and move up and down until the key is fully inserted. Once fully inserted, if the correct key has been used, then the top of each key pin will align with the shear line. The driver pins will have been pushed up and will now fully sit within the housing while the key pins sits fully within the plug. This means the plug is now able to rotate. If the wrong key is inserted then the pins will not align and the plug will be unable to rotate.


   



    The key is inserted into the plug. The different sized key pins rest inside a number of holes inside the plug and will move up and down to follow the profile of the key. If the correct key is inserted then the top of the key pins will align with the top of the plug. This pushes the driver pins out of the plug holes and into their respective chamber. The springs ensure the driver pins will be forced into the holes if the wrong key, or if no key, is inserted.


   



    With all the pins cleared, the key can rotate the plug. At the end of the plug is a cam which also rotates with the plug. This connects with the arms of the two latches. The latches are pushed outwards by a spring, this pushes the arm against the cam but also pushes the latch into a notch on the shackle preventing the lock from opening without the key. With the correct key inserted the plug is free to rotate, this rotates the cam which pulls the latches inwards against the spring, releasing the shackle. A spring within the shackle chamber pushes the arm outward releasing the lock.


   



   



    Nowadays, there are many gifts you can give your loved ones. Often, you wonder what to give that special someone to let them feel that you love them forever. Perhaps a love padlock engraved with a message would work.


   



    Engraved padlocks are the new trend and are available for you online on Amazon, or you can visit your local gift shop. Love locks are excellent symbols of commitment to a lover, a friend, family, e.t.c. They are a perfect way to express to someone what they mean to you.


   



    Traditionally, people hang the padlocks on bridges, but you may have other creative ideas. However, some lovelocks do not come with keys. They symbolize locking your love forever. Here are a few engraved padlocks you can consider.


   



    Let us begin,


   



    40mm Personalized Engraved Love Lock


    The solid brass 40mm engraved disc padlock is a beautiful design with a permanent message engraved in bold letters. You can see the writings under most lighting conditions.


   



    It comes with an attractive, black gift box, whose price is overall. It is easily customizable according to your tastes and preference. The gift box also has engravings of your liking, and the letters come with a unique design. You can also look for ones on Amazon with the message you want or place an order with the exact specifications you need. You can also visit your nearby gift shop and select or order one from the manufacturer.


   



    The engraved love lock has a shiny brass color on the top area and a golden color on the bold writings. It comes with a pair of functional keys which resemble the tri-circle padlock design. The 40mm engraved love lock is an ideal gift for father’s day, mother’s day, birthday parties, wedding anniversaries, valentines, e.t.c.


   



    Long Shackle lovelock Double Shaped Heart


    It comes in many exciting colors such as pink, red, blue, purple, e.t.c. The long shackle would be a lovely present for someone who loves colorful items. You can also order the color you like with the message of your liking engraved on it. There is a gift box available which you can also personalize with a message.


   



    The long shackle engraved padlock does not have a key, so on one end, it has a small colored rubber or plastic seal for decoration. The large latch is ideal for hanging on a bridge with your loved ones.


   



    It is an excellent gift for colorful occasions such as weddings, Valentine’s day, birthdays, e.t.c. It has a heart-shaped design that captures the essence of love once you set your eyes on it. You can order it online on Amazon or any gift shop outlet available to you.


   



    Bird pink 4 Digit Combination Love Lock


    It has a unique and stunning combination of colors. It can get personalized with paintings of your choice to make it more customizable. The material of the love lock is alloy steel and stainless steel that makes it high security. The four-digit combination makes up for the keys, for you can unlock it automatically using the password you set.


   



    It is ideal for locking gym lockers, luggage, sheds, gates, e.t.c. You can personalize it by engraving it with a message to a friend, family, or spouse. You can make a few clicks online and order it from Amazon or visit your nearby gift shop to get a customizable one.


   



    Engraved love lock Necklace


    Engraved Padlocks come in a variety of designs ranging from chokers to necklaces and chains. The pendant can be heart-shaped, square, rectangle, or any personalized shape you want. Gifting a love lock necklace engraved with a message is a thoughtful idea. You can also hang it on bridges if you prefer memorable romantic moments.


   



    An engraved golden heart necklace might be just the thing your spouse needs if he/she likes fancy necklaces. You can purchase them on Amazon or your local jewelry or gift shop.


   



    Heart Engraved PadLock and Key Set


    These charming engraved heart lock engraved laminated padlock will melt your heart once you set your eyes on them. They have the most romantic message engraved on them. You can easily customize them with the type of message you want. In most cases, the message will either be just what you wanted to convey or will be beyond your expectations. They also come in the most endearing colors, light pink, shiny grey, silver, gold, e.t.c.


   



    The product is a perfect wedding and couple gift since it comes with a wedding card box. These pretty love locks are available on Amazon, or you can check them out at your nearby gift shop.


   



    Iron Antique Vintage Engraved Love Lock


    The Iron Antique Vintage Engraved padlock is also called the “love rock”. It’s common among couples, sweethearts, love birds who usually lock it on a bridge, tree, gate, and other placements to symbolize their love.


   



    The interest in love padlocks has spiked since the turn of the century as more people look for different ways to express their love to each other. The vintage love lock features a customized engravement on individual pieces. Some versions have rustic textures to highlight how long both individuals have been together.


   



    You can buy the Iron Antique Vintage Engraved Padlock as a gift to your special friend through online platforms such as Etsy. The engraving gives a personal touch to the item added to the lock includes two skeleton keys (one for each partner).


   



    Silver-Tone Heart- Shaped Love Lock


    The silver Tone Heart Shaped love lock gestures a love-shaped design coupled with a personalized engraving on its surface. You can opt for a name, quote, verse, etc. The product also comes with a key for unlocking.


   



    The engraved weatherproof padlock comes in a dominant silver-white color, sleek design measuring between 1.75” by 1.40” by 4.0” in height. You can also purchase the product enclosed in a gift box and a bow ribbon for a more personalized touch. The Silver Tone Heart Shaped love lock is suited for gifts, birthday presents, and on special occasions.


   



    Vintage Copper Engraved Padlocks


    Copper love locks have existed for a long time. These love locks come off as extremely durable, safe, and highly customizable. You can purchase the products from online stores such as Amazon and eBay or at antique stores. It becomes even more meaningful when you gift it to your spouse, loved one, or friend.


   



    Vintage copper gives off a rustic look that seems to transcend the realms of time. It has an old-school feeling and might feature other unique properties such as the shape of the keys and the overall aesthetics of the engraved padlock.


   



    Bottom Line:


   



    Engraved padlocks are unique locks in every aspect. In contrast to standard versions, they provide a special message and give off a personalized feel to the product.


   



    Engraved padlocks are perfect gifts for occasions such as graduations, valentine’s day, birthdays, engagements, wedding ceremonies, marriage anniversaries, etc. I am sure you will agree with me that before adopting extravagant decisions, such as locking up stuff with them, a gift like an engraved padlock from someone would be something you would treasure.

Intelligent Mining Technology for an Underground Metal Mine Based on Unmanned Equipment

    Intelligent Mining Technology for an Underground Metal Mine Based on Unmanned Equipment


    This article presents facts and figures on mining equipment safety and reviews various important aspects of mining equipment safety including quarry accidents, electrical accidents, equipment fires, maintenance-related mining accidents, causes of mining equipment accidents and major ignition sources for mining equipment fires. A number of methods considered useful for performing mining equipment safety analysis are also presented. Useful strategies to reduce mining equipment fires and injuries, guidelines to improve electrical safety in the mining industry, and human-factor-related tips for safer mining equipment are discussed.


   



    This article analyzes the current research status and development trend of intelligent technologies for underground metal mines in China, where such technologies are under development for use to develop mineral resources in a safe, efficient, and environmentally friendly manner. We analyze and summarize the research status of underground metal mining technology at home and abroad, including some specific examples of equipment, technology, and applications. We introduce the latest equipment and technologies with independent intellectual property rights for unmanned mining, including intelligent and unmanned control technologies for rock-drilling jumbos, down-the-hole (DTH) drills, underground scrapers, underground mining trucks, and underground charging vehicles. Three basic platforms are used for intelligent and unmanned mining: the positioning and navigation platform, information-acquisition and communication platform, and scheduling and control platform. Unmanned equipment was tested in the Fankou Lead-Zinc Mine in China, and industrial tests on the basic platforms of intelligent and unmanned mining were carried out in the mine. The experiment focused on the intelligent scraper, which can achieve autonomous intelligent driving by relying on a wireless communication system, location and navigation system, and data-acquisition system. These industrial experiments indicate that the technology is feasible. The results show that unmanned mining can promote mining technology in China to an intelligent level and can enhance the core competitive ability of China’s mining industry.


   



    With the world’s rapid economic development, the demand for mineral resources is increasing. It has been forecast that the depth of more than 33% of the metal mines in China will reach or exceed 1000?m within the next decade. Deep underground mining will become the trend of metal mining in China [1]. To overcome the disadvantages of traditional mining methods, such as excessive resource consumption, poor operating environments, low production efficiency, high safety risks, high production costs, and severe pollution, it is essential to develop an intelligent mining technology for underground metal mines that provides complete safety, environmental protection, and efficiency [2], [3]. Some developed countries have done a great deal of work in the field of intelligent mining for underground metal mines over many years, and thus have considerable experience in this field. At the beginning of the 21st century, Canada, Finland, Sweden, and other developed countries made plans for intelligent and unmanned mining. At the Stobie Mine, an underground mine belonging to the International Nickel Company of Canada, Ltd. and a typical example of such an automated mine, mobile devices such as scrapers, rock drills, and underground mining trucks are operated remotely and workers can operate the equipment directly from the central control room on the surface [4]. According to the Canadian government’s 2050 long-range plan, Canada intends to transform one of its underground mines in the northern part of the country into an unmanned mine. The plan states that all devices will be controlled from Sudbury via satellite in order to achieve intelligent and unmanned mining. Another intelligent mining program covering 28 topics—including the real-time process control of mining, real-time management of resources, construction of a mine information network, and application of new technology and automatic control—was carried out in Finland. Sweden has developed the Grountecknik 2000 strategic plan for mine automation [5], [6], [7], and veteran mining equipment companies such as Atlas Copco are actively developing a series of unmanned underground gold mining equipment and related control systems that can be used to implement the strategic plan. One of the most famous institutes in unmanned vehicles, the Commonwealth Scientific and Industrial Research Organization of Australia, is making great efforts to achieve the intelligent mining of underground mines, with a particular focus on the unmanned control of various types of equipment [8].


   



    Although these developed countries have already invested a considerable amount of time and money into the study of intelligent mining, only a few related studies have been carried out in China, especially in the field of intelligent equipment and platforms. In order to rapidly advance its intelligent mining capabilities, China is supporting many intelligent mining projects, including the Key Technology and Software Development for Digital Mining project and the High-Precision Positioning for Underground Unmanned Mining Equipment and Intelligent Unmanned Scraper Model Research project. In particular, a project titled Intelligent Mining Technology for Underground Metal Mines was established during the 12th Five-Year Plan, in order to promote intelligent mining technology to a certain extent. This article introduces several research achievements and their applications in this project. Trackless mining equipment such as rock-drilling jumbos, down-the-hole (DTH) drills, underground scrapers, underground mining trucks, and underground charging vehicles have been developed using intelligent technologies. Suitable communication techniques, sensors, artificial intelligence, virtual reality, information technology, and computer technology for mining equipment and platforms have been implemented. The experimental results indicate that some of the system’s functionalities are innovative and show good performance.


   



    2. Intelligent mining


    Mining is one of the oldest industries in the world. environmental protection equipment techniques have passed through a rapid change from artificial production, mechanized production, and on-site remote-control production, to intelligent and fully automated production. In order to move the mining industry forward, mechanization tools have been developed, single-equipment and independent systems have been automated, and the entire mining production process has been highly automated [9]. By integrating information technology with the industrialization of mining technology, intelligent mining technology has been rapidly developed, based on mechanized and automated mining, as shown in Fig. 1. This has resulted in the gradual upgrading of intelligent processes in mining equipment; unmanned and centralized mining equipment have now entered the stage of practical application, which will significantly advance the automation and information technology used in mining [10].


   



    Integrated communication, sensors, artificial intelligence, virtual reality, information technologies, computer technologies, and unmanned control equipment were combined in order to achieve intelligent mining technologies, as shown in Fig. 2. Such technologies are based on precise, reliable, and accurate decision-making and production process management through real-time monitoring; they allow mine production to be maintained at the optimum level, and lead to improved mining efficiency and economic benefits. In this way, green, safe, and efficient mining can be achieved.


    Taking a typical trackless mining technology as an example, intelligent mining technology can be divided into three layers—the control layer, transport layer, and executive layer [11].


   



    As shown in Fig. 3, the executive layer mainly consists of trackless mining equipment such as rock-drilling jumbos, DTH drills, underground scrapers, underground mining trucks, or underground charging vehicles. The transport layer mainly includes a ubiquitous information-acquisition system, wireless communication system, and precise positioning and intelligent navigation system. The control layer is designed as a system-level platform, and is responsible for intelligent mining process scheduling and control. This is the core of the entire system, because all intelligent mining-related functions and control ideas are implemented through this platform. First, a reasonable gold and diamond mining equipment plan is designed by analyzing the reserves of mine resources and geological conditions in combination with the underground production schedule. Next, an intelligent scheduling and control platform is developed. Control instructions for the equipment are sent through the transport layer to a specific piece of equipment in order to perform a mining task at a specific position and time. Within the executive layer, the control layer collects current information on the tunnel and basic information about the vehicle in real time; this information can be used to determine the location of the equipment or adjust it at any time until that entire stage of the mining plan is successfully completed.


   



    Intelligent trackless mining technology is based on intelligent unmanned equipment at the executive layer, such as rock-drilling jumbos, DTH drills, underground scrapers, underground mining trucks, or underground charging vehicles. The functions of intelligent and unmanned diamond mining equipment differ according to the different tasks each piece of equipment must carry out.


   



    3.1. Intelligent rock-drilling jumbo


    Rock drilling is the key process in mining, and plays a very important role in productivity, cost, and efficiency. Different geological conditions require different mining methods, and different methods require different types of rock drilling. A hydraulic rock-drilling jumbo is needed for medium-length hole drilling (i.e., depth of 20–30?m, diameter of 60–100?mm) [12]. An intelligent and unmanned rock-drilling jumbo has been designed to support intelligent mining technology and efficiently complete drilling work.


   



    Remote control and a virtual-reality display were the first basic technologies implemented in the unmanned hydraulic rock-drilling jumbo. Fig. 4 shows the initial unmanned control platform for the jumbo on the surface. The virtual prototype display system, including on-site audio and video signals, is well-integrated in order to increase the feeling of immersion while performing remote-control operations.


   



    Furthermore, the rock-drilling jumbo is autonomously controlled and operated in the tunnel under the guidance of a positioning and navigation system. By coordinating the positioning system and altitude control system, the jumbo can achieve autonomous driving to the location from the dispatch layer. This is a major step toward achieving continuous operation without interference. Given the coordinates of the drilling-hole position in the three-dimensional (3D) digital map of the mine, the identification of the stope top and floor and the accurate positioning of the rock-drilling system can be achieved independently. This provides a basis for unmanned operation. The intelligent control flow diagram is shown in Fig. 5.


   



    The rock-drilling parameters are independently adjusted according to the rock conditions. The intelligent rock-drilling jumbo (shown in Fig. 6) is equipped with components for intelligent blockage prevention, rock-characteristic acquisition, and frequency matching; an automatic rod function; and a fully automatic drill-pipe bank. The hole-blasting parameters are specified independently, according to the scheduling system that is used, in order to ensure continuous drilling.

The current coronavirus 2019 disease (COVID-19) pandemic has greatly changed our perspective of the risk for infection from contact, and the use of personal protective devices (PPDs) usually reserved for health care workers (HCWs) has spread to the general population, sometimes indiscriminately. As a result, medical glove stock has been depleted, but most of all medical gloves have become a source of medical concern.[1], [2], [3], [4]

The World Health Organization (WHO) has warned about the limited protective efficacy of gloves. There is high risk for infection spread with their incorrect use that could instead favor the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Regular use of gloves for daily activities may lead to a false sense of protection and to an increased risk for self-contamination. This would involve the involuntary touching of the face or the spreading of fomites to desks, phones, and computers keyboards. A study has found that viruses can survive on gloves for 2 to 4 hours.5
Hand-to-face contact has a substantial role in upper respiratory tract infections,6 , 7 although COVID-19’s main way of transmission remains symptomatic person-to-person through respiratory droplets.[1], [2], [3], [4] The Centers for Disease Control and Prevention (CDC) and the European Center for Disease Prevention and Control (ECDC) have recently provided guidance to regulate the use of gloves both in the health care setting and in the community.2 , 4 In the context of the COVID-19 pandemic (Table 1 ), gloves are recommended when caring for confirmed or suspected COVID-19 patients, especially when there is the risk of contact with body fluids (eg, blood, wound care, aerosol-generating procedures).

Hand protection with gloves is essential in any medical procedure, because skin cleaning/disinfection alone does not remove all pathogens, especially when the contamination is considerably high. Nonsterile disposable gloves should be prioritized, and ECDC alerts that no direct evidence documents an increased protection against COVID-19 through glove use, compared with proper hand hygiene alone. Meticulous hand hygiene with water and soap or by alcohol-based hand rub solutions is not avoided by the use of gloves.

There are many different types of gloves, depending on the level of protection, tactility, risk of allergy, or cost (Table 2 ). Although biohazard risk requires frequent glove changing, the extended use of gloves, decontamination with hand disinfectants, and reuse are frequent.8 All of this should be avoided, because effects of hand sanitizers are tested on the skin, whereas application on gloved hands affects gloves’ mechanical properties. In a recent investigation,9 the application of 70% ethanol or 63% isopropanol commercial disinfectants reduced the tensile strength of latex and nitrile gloves, with a higher impact on nitrile gloves. Elongation did not change much with latex gloves, but nitrile gloves were affected. There are additional concerns about permeability, as alcohol can permeate any type of glove after 10 minutes. Some types of disposable gloves are permeated at 2 minutes, and repeated exposure to disinfectants can increase the permeability of the gloves. Alcohol is inactivated in the presence of organic matter, which can easily remain on used gloves, thus potentially driving the viral transmission.

Extended length gloves are not necessary when providing care to suspected or confirmed COVID-19 patients. They are not specifically recommended, except for activities with increased risk, such as submerging hands into a solution. For standard procedures, it is sufficient to cover the cuff (wrist) of the gown while donning.[1], [2], [3], [4]

Another common measure that is no longer recommended is “double gloving,” except for surgical procedures that carry a high risk of disrupting the integrity of the glove. Double gloving seems to increase the incidence of dermatologic side effects, from irritation and overhydration to induction of latex allergy. The increase of skin damage as the consequence of overzealous PPD use and hand hygiene is an emergent consequence of the COVID-19 handling.[10], [11], [12]

About 74.5% of front-line COVID-19 HCWs developed hand dermatitis in the Chinese experience.13 A questionnaire-based study suggested that 88.5% of skin reactions on the hands are associated with the use of latex gloves.14 Three types of adverse events might occur: latex allergy, talcum powder reactions, and irritant dermatitis. Excluding latex allergy and powder within the gloves, the problem of excessive dryness and pruritus, associated with irritant dermatitis, may be aggravated by occlusion, leading to sweating and/or overhydration. This then may increase the permeability to sanitizers or detergents, creating a vicious cycle, plus aggravation of hand dermatitis.12

A peculiar pattern of hand dermatitis has been recognized, characterized by erythema and fine scaling on the palms and web spaces.15 This may be attributed to the depletion of surface lipids, resulting in deeper penetration of detergents, and progressive damage of skin layers is a major pathogenetic mechanism. Irritant contact dermatitis is more commonly found with iodophors, chlorhexidine, chloroxylenol, triclosan, and alcohol-based products, whereas allergic contact dermatitis develops due to quaternary ammonium compounds, iodine or iodophors, chlorhexidine, triclosan, chloroxylenol, and alcohol sensitization.

To date, there have been no verified reports of COVID-19 infection as direct consequence of skin damage. Angiotensin-converting enzyme 2 (ACE2), which is the main cell receptor for SARS-CoV-2 entry, can be expressed in the basal layer of the epidermis, hair follicles, and eccrine glands, as well as on skin blood vessels.16

Basic skincare measures should be taken to avoid the risk of SARS-CoV-2 entry through the skin.[10], [11], [12], [13], [14], [15] Careful hand skin drying and hypoallergenic hand cream/emollients may be employed to prevent trapping sanitizers in the web spaces. Emollients may also be applied at other times to correct any residual dryness and scaling, or with the occurrence of hand dermatitis, topical corticosteroids are indicated.

A final consideration is the generation of massive amount of medical waste, caused in part by the extensive use of PPDs.17 HCWs, together with the general population, are using more gloves than ever before, whereas it should be limited to very essential preventive measures.


Medical gloves remain an essential part of the infection-control strategy; however, caring for patients with COVID-19 has pointed out the need for more accuracy and respect of novel guidance. Prolonged use of gloves, outside of direct patient contact, might be self-defeating rather than protective. Hand dermatitis is an emerging concern. At this time, the U.S. Food and Drug Administration has not cleared, approved, or authorized any medical gloves for specific protection against the virus that causes COVID-19 or prevention of COVID-19 infection.

Broadly speaking, there are 2 types of medical gloves: examination gloves, which are ambidextrous, usually nonsterile, and come in a small range of sizes, are used for nonsterile and less dextrous tasks and also for most dental work; surgical gloves are sterile, come individually packaged in handed pairs, and are usually available in half-inch intervals of hand girth. They are used in the operating theater for a variety of dextrous tasks, ranging from microsurgery on the eye or ear to bone setting or hip replacement.
Because the majority of clinical work is not perceived to be as dextrous as surgery, less emphasis is placed on the performance of examination gloves. Until recently, both examination and surgical gloves were generally made from natural rubber latex (commonly referred to as “latex”), although alternatives were available for known cases of latex allergy. However, the lack of regulation of manufacturing processes in the early years of mass production meant that gloves often contained a high level of allergenic proteins, which led to a steady increase in the number of cases of latex allergy reported.1

Current guidelines from the National Health Service and the Royal College of Physicians2 in the United Kingdom state that “the evidence does not … support a need to ban latex completely from the workplace.” They note that nonlatex surgical gloves “have higher failure rates in use and lower user satisfaction than latex gloves.” Instead, they advocate the use of nonpowdered, low-protein latex gloves, except for employees with latex allergy, latex sensitization, or latex-induced asthma, where nonlatex alternatives are recommended. However, most primary care health care groups and hospitals in the United Kingdom have replaced latex in nonsurgical situations with less flexible alternatives3 such as nitrile to remove the risk of latex allergy in patients and practitioners.
Similarly, the American College of Allergy, Asthma, and Immunology4 recommends that “a facility-wide review of glove usage should be undertaken to determine the appropriateness of use … and thereby prevent the unnecessary use of latex gloves” and advocates nonpowdered, low-protein gloves as standard in a health care facility but also states that “hospitals need to evaluate manufacturer information on nonlatex gloves in areas of durability, barrier protection, and cost” because “latex is still considered superior with respect to barrier characteristics against transmissible diseases.” Surgeons have generally resisted moves to replace surgical gloves in the same way because of the perceived reduction in manual performance when using nonlatex alternatives.

With respect to the glove design process, there is little or no evidence that gloves are evaluated in terms of their effects on users’ manual performance. All the currently available standards5,  6 focus on the barrier integrity of the gloves by defining tensile strength, freedom from holes, and tear resistance. Similarly, much of the research on medical gloves has concerned barrier integrity7,  8 and adherence of practitioners to handwashing and glove handling guidelines.9,  10 Clearly, because the primary role of the gloves is to prevent the spread of infection, it is important that the design brief takes these things into consideration, but achieving good barrier integrity is not necessarily incompatible with achieving the best performance.

Glove performance also has an effect on safety, particularly in a surgical environment. Surgeons using plastic gloves with less-than-optimal frictional properties, for example, may be more likely to drop instruments, to slip when performing delicate procedures, or to increase their stress levels when attempting to compensate. Similarly, practitioners who cannot feel a pulse through gloves when taking blood will be more likely to remove the gloves and increase their risk of infection. A 1994 survey of health care workers11 found that a “perceived interference with technical skills” was a common obstacle to compliance with universal precautions. There is also a subjective element to the performance that must be considered, which is that practitioners’ comfort and confidence in their gloves may affect their concentration levels and therefore their ability to perform surgery over extended periods of time.

It is vital that the glove design process includes an assessment of their effect on manual performance to ensure that practitioners can operate safely and efficiently. The first step in this process is to determine the key aspects of manual performance in medical practice and where current gloves have a significant adverse effect. The second is to design tests that are useful predictors of clinical performance. It is therefore necessary to identify the tasks that are most challenging and on which gloves are thought to have the greatest impact so that the tests can be designed to simulate relevant manual skills.

To achieve this, semistructured interviews with medical practitioners were carried out. As well as gathering information on the participants’ roles, disciplines, and glove use, a series of open-ended questions were used to identify tasks believed by users to require the most dexterity and tactility, and those most affected by glove performance, as well as any other issues related to HDPE gloves that might aid the study. The interviews took place within Sheffield Teaching Hospitals NHS Foundation Trust (STH) and received ethical approval from the research ethics committees of STH and The University of Sheffield, UK.

Focus groups were considered as a means of gathering data fairly quickly and stimulating discussion. However, the limited availability, particularly of senior staff, made this a difficult approach. Furthermore, it has been shown12 that, when recruitment, transcription, and analysis are included, focus groups can be much more time-consuming than individual interviews. Although focus groups are generally accepted to produce a wider range of responses, this is not always the case and depends on the nature of the questions.12,  13 In this study, many of the questions were of a technical nature and specific to the individual’s specialty. There was also a concern that participants’ opinions on specific gloves would be influenced by those of their colleagues.
Interviews were therefore conducted on a one-to-one basis to increase flexibility and enable senior staff to participate at their own convenience, often between operations or appointments. The questions were designed to be sufficiently open-ended so that the participant was not led down one particular line of thought but also included prompts where information was not forthcoming. With a wide enough selection of participants, it was hoped that a consensus would be formed in at least some of the areas, which would enable judgments to be made on the most productive direction for future research.

Solvent recovery is a form of waste reduction. In–process solvent recovery still is widely used as an alternative to solvent replacement to reduce waste generation. It is attractive, like end–of–pipe pollution control, since it requires little change in existing processes. There is widespread commercial availability of solvent recovery equipment which is another attraction. Availability of equipment suitable for small operations, especially batch operations, make in–process recovery of solvents economically preferable to raw materials substitution.

Commercially available solvent recovery equipment include:

Carbon adsorption of solvent, removal of the solvent by steam, and separation of the solvent for reuse in the operation. Carbon must be regenerated, two or more units are required to keep the operations continuous. Chloric acid formation from chlorinated solvents, carbon bed plugging by particulates, and buildup of certain volatile organics on the carbon and corrosion can be a problem.

Distillation and condensation can be used to separate and recover solvent from other liquids. Removal efficiency can be very high using this process and can be used for solvent mixtures as well as single solvents.

Dissolving the solvent in another material such as scrubbing. Solvents must be then recovered from the resulting solution, through distillation but efficiency of removal is often not high using this method.

Adsorption processes are useful and versatile tools when it comes to waste solvent recovery unit as they can be applied with high efficiency at relatively low cost in cases in which the desired component presents either a fairly small or a fairly high proportion of the stream. The applicable adsorbents vary according to different purposes.108,109 Adsorbents with low polarity (activated carbon, etc.) tend to adsorb nonpolar compounds, whereas ones with high polarity (e.g., silica, alumina) have higher affinity to adsorb polar substances. However, some adsorbents operate via specific binding sites (e.g., molecular sieves, molecularly imprinted polymers) rather than simple hydrophilic-hydrophobic interactions. It is worth mentioning that adsorption cannot easily be installed in a continuous configuration and is usually either a one-bed batch process or a twin-bed process with one bed in the adsorption, whereas the other one in the regeneration phase.

In organic solvent recycling, the most frequent issue is the removal of water content. Even traces of water can cause unexpected solubility problems, side reactions, or the decomposition of a reactant. There are various processes to recover wet solvents such as distillation methods or fractional freezing, whereas adsorptive methods are advantageous due to their low energy consumption. Molecular sieves (with pore size 3 or 4 Å), silica, and alumina are widely used for solvent drying.110,111 The polarity of the solvent affects the efficiency of water removal, which decreases with increasing polarity of the solvent. With the proper choice of adsorption technique, residual water content between 1 and 100 ppm is usually a realistic target.

In the regeneration stage of adsorption, high volumes of gas containing organic solvent are produced. Other processes in the chemical industry, such as paint drying or the drying of solid pharmaceutical intermediates or products, also generate a significant amount of solvent vapor.112 This raises another issue, as the recovery of this solvent is highly desired to minimize solvent loss and the environmental burden, as urged by the increasingly strict regulatory environment. For example, the recycling of chlorofluorocarbons has gained a lot of attention since the Montreal protocol.113–115 Incineration of solvent vapors is a widely used solution since it makes use of the solvent's latent heat. However, incineration likely needs supporting fuel to reach the required efficiency and needs continuous solvent vapor feed, not to mention that nonflammable halogenated solvent cannot be eliminated in this manner. Adsorptive systems have proved to be good alternatives. This field of adsorption is dominated by activated carbon adsorbents,116 but molecular sieve zeolites are also employed.117 Polymeric adsorbents are seldom employed in such processes, mainly because of their high price compared with activated carbon and zeolites.118 The choice of adsorbent regeneration technique has a significant effect on the quality of the recovered solvent. Examining the efficiency and applicability of various regeneration processes has been the aim of several studies.112,119 A typical system utilizing activated carbon adsorption to recover solvents from air emissions is shown in Fig. 3.15.11. Steam regeneration is employed to strip solvents from the activated carbon followed by condensation of the steam/solvent mixture through cooling. Eventually the solvent layer is separated by simple decantation.

The integrated production and recovery of ABE using glucose as a substrate and gas stripping as a means of solvent recovery distillation equipment has been reported by Groot et al. [39], Mollah and Stuckey [40], Park et al. [41], and Ezeji et al. [42–44]. Groot et al. produced butanol in a free cell (not immobilized) continuous reactor and removed the product in a separate stripper [39]. As a result of simultaneous product recovery, glucose utilization was improved by threefold, but the selectivity of butanol removal was low at 4 as compared to 19, which is the selectivity at equilibrium, suggesting that the stripper was not efficient. Also solvent productivity in the integrated system was 0.18 g/L h, as compared to 0.17 g/L h in the nonintegrated batch system [39]. Mollah and Stuckey used immobilized cells of C. acetobutylicum to improve productivity and recover butanol by gas stripping [40]. The cells were immobilized in calcium alginate gel and used in a fluidized bed bioreactor. This integrated system achieved a productivity of 0.58 g/L h, which is considered low for an immobilized cell continuous reactor.

Ezeji et al. tested the use of a hyper-butanol-producing strain, Clostridium beijerinckii BA101, in an integrated system with butanol produced in a free cell fed-batch reactor coupled with in situ product recovery [43]. As a result of simultaneous product recovery, the rates of fermentation (productivity) and glucose utilization improved. To compensate for the utilized glucose, a concentrated sugar solution (500 g/L) was intermittently fed into the reactor to maintain a solventogenic substrate concentration. This reactor was operated for 207 h before the culture stopped fermentation due to the accumulation of unknown inhibitory products. In this system 500 g/L glucose was used to produce 232.8 g/L ABE. ABE productivity was also improved from 0.29 g/L h in a nonintegrated batch system to 1.16 g/L h in the integrated system, a 400% increase. Given that the fed-batch fermentation stopped due to the accumulation of unknown inhibitory products, the authors devised another system in which a semicontinuous bleed was withdrawn from the reactor to eliminate or reduce the accumulation of unknown toxic by-products. As a result, the continuous reactor was operated for 21 days (504 h) before it was intentionally stopped [44]. Results from this continuous reactor suggest that ABE fermentation can be operated indefinitely in continuous mode, provided that toxic butanol is removed by gas stripping and unknown toxic products are removed by a bleed. In a 1-L culture volume, the system produced 461.3 g ABE from 1125.0 g glucose, with an ABE productivity of 0.92 g/L h, compared to 0.28 g/L h productivity in the nonintegrated batch system.

Adsorption is a physical process in which organic species are transferred onto the surface of a solid adsorbent. Adsorption is a particularly attractive control method as it can handle large volumes of gases of low pollutant concentrations. It is capable of removing contaminants down to very low levels.1 Removal efficiency is typically greater than 95%. The most frequently used adsorbent in the organic compound applications is activated carbon, although zeolites and resins are also used.

Adsorption is the most widely used solvent-recovery technique and is also used for odor control. The latter application is necessary to meet statutory air pollution control requirements. Depending on the application, adsorption can be used alone or with other techniques such as incineration.14
Solvent recovery with adsorption is most feasible when the reusable solvent is valuable and is readily separated from the regeneration agent. When steam-regenerated activated-carbon adsorption is employed, the solvent should be immiscible with water. If more than one compound is to be recycled, the compounds should be easily separated or reused as a mixture.9 Only very large solvent users can afford the cost of solvent purification by distillation.’

The advantages include the availability of long-term operating data. In addition, adsorbers can handle varying flow rates or varying concentrations of organic compounds. The main disadvantage of adsorption is the formation of a secondary waste, such as the spent adsorbent, unusable recovered organic compounds, and organics in the waste water if steam is used for regeneration. Secondary waste may require off-site treatment or specialist disposal.12 (see Table 13.12)

In addition to air, moisture and photochemical stability, the thermal stability is an important aspect of improving the economy of the process. The occurrence of thermally induced polymerization or decomposition reactions results in a loss of solvent recovery potential, specialized facilities for the treatment and post-purification of solvents and product streams and poor flexibility in the optimization of the thermal profile of the process (solvent extraction and extractive distillation steps). N-Methyl pyrrolidone has been shown to be chemically and thermally stable in the Arosolvan process. Sulpholane is reported to be stable to 493 K and undergoes some decomposition at 558 K [23]. In the sulpholane process, the influence of oxygen on solvent stability in the form of minor oxidative degradation has been observed under normal operating conditions. Consequently, the exclusion of air in the feed to the extraction unit has been advocated for this process together with the inclusion of a solvent regenerator unit. The latter operates by removing oxidized solvent from a small side-stream of the circulating solvent that is directed towards the solvent regenerator unit [16]. Ionic liquids exhibit excellent thermal stability and lack of sensitivity to oxygen would be advantageous with respect to the processing and recovery of the solvent.

Pfizer has redesigned the synthesis of several of its pharmaceutical products to reduce generation of hazardous waste. Changes were made in the synthetic route to sildenafil citrate (see Fig. 9.7), the active ingredient in Viagra® (Dunn et al., 2004), which resulted in a more efficient process that required no extraction and recovery system for solvent steps (see Fig. 9.8). The E-factor (Sheldon, 1992) for the process is 6 kg waste/kg product, which is substantially lower than an E-factor of 25–100, which is typical of pharmaceutical processes. Furthermore, all chlorinated solvents had been eliminated from the commercial process. During the medicinal chemistry stage in 1990, the solvent usage was 1816 L/kg, and the optimized process used 139 L/kg solvent, which was reduced to 31 L/kg during commercial production in 1997 and to 10 L/kg with solvent recoveries. Pfizer plans to replace t-butanol/t-butoxide cyclization with an ethanol/ethoxide cyclization. Combined with other proposed improvements, this is expected to increase the overall yield from 76–80% and further reduce solvent usage and organic waste.

A first point of economic comparison is the variable cost requirements of each process. Here, variable costs are defined as the sum of all raw materials costs plus the utilities cost for conversion of raw materials to product. All labor, overheads and depreciation costs are not included. On a variable cost basis, both the diacetate and diphenate routes show a distinct advantage over the acid chloride route. The largest component of the cost differential results from the high cost of the acid chloride monomers relative to the free acids. The second largest component arises because the acid chloride process inherently uses greater solvent volumes than the other two routes. Solvent losses which invariably occur contribute to increased variable cost as the solvent recovery processes are not completely efficient. Variable cost differences between the diacetate and diphenate processes are not very large. Both processes can be thought of as variations to reacting free diphenol with the free diacids. In the diacetate variation, acetic anhydride is consumed in forming the diacetate, but some of this cost is recouped by selling acetic acid — the process by-product. In the diphenate route, phenol is first consumed in monomer preparation, then recovered during the polymerization. The variable cost of the diacetate route may be slightly higher than that of the diphenate route due to the conversion of anhydride to acetic acid, but this disadvantage can be mitigated depending on the phenol recovery/recycle efficiencies in the diphenate process.

Secondly, the capital investment requirement required to construct facilities to practice each of the three process technologies can be compared. The acid chloride process is a low temperature, atmospheric pressure process and process fluid viscosities are low. Thus, standard design reaction equipment with low cost supporting utilities are used in the reaction area. However, polymer recovery would generally be accomplished by precipitation, washing and drying followed by extruder pelletization — operations which are capital intensive. Also, extensive used solvent recycler for sale is required in the acid chloride process, again leading to increased capital cost. Both the melt or solution diacetate and diphenate processes on the other hand are high temperature, high vacuum processes where process fluid viscosities reach very high values. For these processes, polymer reactors will require some special design features particularly with respect to agitation and heat transfer. Supporting utilities will be rather capital intensive. To balance these costs, however, product recovery is expected to be relatively simple, requiring only one or two melt processing operations most likely using a thin film polymer processor followed by an extruder. Solvent recovery requirements would be modest for the diacetate process but somewhat more costly for the diphenate process where large quantities of phenol (especially from monomer production) will require purification prior to recycle. Some difference in capital investment required for monomer production in the diacetate and diphenate processes is also expected. Diphenyl ester production is less attractive due to the more extreme reaction conditions required and the large phenol recycle streams. However, even with the noted differences, it is estimated that any of the three described processes could be built for approximately the same dollar amount per annual pound of polymer capacity at the 15 Mlb year−1 scale (1 kg = 2.2 lb).

On the paper machine, the size press is used to apply surface size to dried paper.182,183 Starch is the most frequently used binder in surface sizing. Besides raising surface strength, starch also imparts stiffness, lowers water sensitivity, reduces dimensional changes and raises air leak density of the sheet. In conventional practice, the sheet passes through a pond of starch dispersion held above the nip between two large rotating cylinders. In the nip a high, transient, hydrostatic pressure is developed. Excess starch dispersion is drained from the ends of the nip. The surface size is transferred to paper by capillary penetration, pressure penetration and by hydrodynamic force during nip passage.

The quantity of starch transferred to paper by a size press depends on several factors: concentration of dispersed starch in the surface size; viscosity of the starch dispersion; diameter of the size press rolls; size press pond height; cover hardness of the size press rolls; size press nip loading pressure; fluting corrugated paper machine speeds; wet-end sizing of the sheet; and water content of the sheet. The concentration of starch in the surface size liquid can range from 2% to ∼15%, depending on product requirements. Frequently, pigments and other materials are added, which further increases total dispersed and suspended solids content. The viscosity ranges from water thin to several hundred cP (mPa·s).

Viscosity of the starch dispersion is the primary rate-determining parameter for dynamic sorption of starch into paper during surface sizing. Surface size penetration into the capillaries of paper proceeds in lateral and normal directions. Lateral flow takes the shape of an ellipse, according to the bias of fiber orientation in machine direction.184 Contributions by wetting and capillary penetration decrease with increasing paper machine speed, while the contribution by hydrodynamic force increases with speed. As a consequence, starch pick-up will pass through a minimum at a specific speed. The hydrodynamic force depends on the angle of convergence (which is determined by the diameter of the rolls), by the nip length (which is influenced by the hardness of the roll covers), by the paper machine speed and by the opposing loading force between the two rolls. High liquid viscosity, large roll diameter, soft roll covers and high newspaper machine speed increase starch transfer, while high nip pressure counteracts these drivers. Starch cationization has no affect on pressure-driven penetration, provided the hydrostatic pressure is high and the viscosity of the dispersion is low.

The transferred liquid penetrates into the sheet according to the void space between fibers and pigment particles. During drying, starch attaches to the fibers and pigment, and reinforces the sheet by ‘spot welding’ and bridging between paper constituents. The ultimate location of the starch in the sheet can be affected by chromatographic partitioning behind a front of water that advances into the sheet. This effect will primarily occur in heavyweight paper and board and may lead to a gradient in starch concentration in the sheet from the surface to the interior and a weakening of internal bond at the ultimate location of free water. Starch application to the sheet induces some desizing due to coverage of hydrophobic patches by hydrophilic starch.

Application of surface size to paper carries with it the transfer of a substantial quantity of water. As an example, surface sizing of a 75 g/m2 (50 lb/3300 ft2) sheet (with 1% residual water content) by a 5% starch solution for a coat weight of 1.5 g/m2 (1 lb/3300 ft2/side) will raise the water content of the sheet to 43%. This large quantity of water will weaken the paper. Web breaks at the size press can occur, particularly when the sheet is also weakened as a result of edge cracks or holes.

Surface sizing can induce structural changes in the paper sheet185 due to the interaction of water sorption (which causes a relaxation of internal stresses) and machine direction tension (which increases anisotropy and creates additional stresses). Anisotropy can be lowered by reducing tension on the web during sheet passage through the size press and subsequent dryers, and by raising the moisture content prior to the size press.

When surface-sized paper leaves the size press, it will cling to a roll and has to be pulled off. The separation force due to film splitting depends on the free film thickness, its cohesiveness, and the rheological properties of the surface size, especially its viscoelasticity. Transfer defects, such as ribbing, orange peel, spatter or misting may result. It is important to control the starch viscosity, to use the correct take-off angle and to apply appropriate web tension. Surface-size splashing can occur due to the converging motion of paper sheet and roll surfaces in the pond and fluid rejection at the nip. Best pond stability is obtained at high or low viscosity, while intermediate viscosity is most prone to induce pond instability.

The same basic test liner paper machine used to produce writing and printing paper are also used to form paperboard. However, modern paper machines are limited in their ability to produce a single-layer paper sheet with a grammage above 150 g m−2. There are a number of reasons for this limitation. Primarily, thicker single-layer sheets are more difficult to dewater requiring excessive reductions in machine speed. Furthermore, the increased drainage forces applied to thicker sheets in the forming section would cause greater fines removal from the bottom of the sheet resulting in a rougher surface. The topside of a very thick sheet would also be adversely affected since paper is formed on fourdrinier machines layer by layer from the wire side up, which would allow extra time for the fibers in the top layer to flock and produce a ‘hill and valley’ appearance. The combination of these two effects would produce an unacceptably two-sided product.

Manufacturing multilayered paperboard from separately formed sheets provides a solution to the above-mentioned problems. The forming section of paperboard machines are composed of two, three, or even four forming sections that bring individual sheets together at the wet press. Paperboard machines are for this reason large and complex having heights that are two to three times greater than single-former machines. Any one of the former sections in a multilayer machine can be either a traditional fourdrinier or a modified fourdrinier equipped with a top-wire unit for additional dewatering capacity. The use of different furnishes in each former produces a final sheet that is engineered for specific stiffness and smoothness requirements.

Although initially forming two to three separately formed sheets of paper, a multilayer machine forms a single sheet of paperboard when the individual sheets of paper are combined together in the wet press. The individual single-layered sheets prior to the wet press are ‘vacuum dewatered’ with a typical consistency of 20% (80% moisture) and are simply assemblages of fibers held together by capillary forces exerted by the continuous matrix of water surrounding the fibers. When the sheet continues it progress through the wet press and the dryers, this continuous matrix of water is decreased and the fibers are progressively drawn together through surface tension. Eventually, at the end of the drying process with a final moisture content of 4–8%, the surface tension forces between individual fibers will produce pressures sufficiently high enough to form fiber-to-fiber hydrogen bonds resulting in a mechanically strong sheet. During multilayer forming, a single sheet of paperboard is formed from the individual sheets of paper by merging the water matrices of each sheet into a single, hydraulically connected matrix in the wet press. The net result is that the multilayer sheet continues through the wet press and dryer section forming fiber-to-fiber bonds inside layers and between layers as if they were initially formed together. Theoretically, the fiber-to-fiber bonding between separately formed layers will be identical to fiber-to-fiber bonding within a single layer. Differences in interlayer bonding strength (measured by z-direction strength tests) will be found when the individual sheets are wet pressed at moisture contents lower than what is necessary to form a hydraulically connected matrix. (z-direction strength is the maximum tensile force per unit area which a paper or paperboard can withstand when applied perpendicularly to the plane of the test sample.)

The advantage of manufacturing a multilayer sheet is that key paper properties can be engineered into the paperboard that would not be obtainable by single-layer forming. Special top layers can be incorporated that are white and smooth, therefore, having excellent printing properties. Middle layers can be used that are bulky and thus inherently thicker producing the stiffest possible board. These middle layers can also contain recycle fibers or pulp fibers of lower quality that can be covered or masked by higher quality top and/or bottom layers.
Although starch is usually added at the wet end of the coated board duplex paper machine as a liquid feed directly to the furnish, other systems which place the starch directly on the formed sheet while it is still on the wire of the Fourdrinier machine or on the felt of the cylinder machine may be used. Advantages claimed are improved retention and better distribution of starch throughout the sheet, while permitting the use of low-cost unmodified starch.

In one system, a solution of cooked starch or a dispersion of starch granules is sprayed from nozzles directly onto the wet-web of fibers. By varying concentration, spray pressure, and spray location, a variety of effects can be achieved (24, 25). Three types of spray systems are in use: high-pressure air atomization, high-pressure airless atomization, and low-pressure airless atomization. With high-pressure systems, an electrostatic assist is used to prevent loss owing to misting (26).

In another system, low-density starch foam is applied directly on the wet-web immediately before it enters the wet press. The foam is mechanically broken at the press nip, and the starch is dispersed through the sheet. By controlling foam density, bubble size, and starch concentration, a wide variety of results can be achieved (27). As in the spraying system, very high retentions are possible, and low-cost unmodified starch may be used.

In another system, a thin curtain of liquid is applied to the wet-web (28) for high retention of chemicals, including starches. This system is claimed to be suitable for addition of starch to multi-ply paperboard where it increases ply bond strength.

In the beginning was the hollowed-out tree trunk, one of the first capillary tube to be crafted by human hand. With a vast array of models in the plant world to inspire him, Homo sapiens had a much easier job inventing the tube than the wheel for which, by contrast, nature had no example to offer. Bamboo and reed are just two examples of plants with hollow stalks. Nature already knew the value of the tubular form, which combines high stability with the capacity to Transport essential substances for growth, such as water and nutrients, out of the earth.

In technical terms, a tube or pipe is a cylindrical, hard hollow body which usually has a round cross-section but can also be oval, square, rectangular or more complex in profile. It is used on the one hand to convey liquid, gas and solid matter and, on the other, as a construction element. Whatever its purpose, the term covers all sizes and diameters, from the smallest needle pipes right up to wind tunnels. No other profile shape with the same material cross-section has such a high flexural strength, which is what makes the tube so important as a load-bearing element in building.

Tubes for transporting purposes

In the past, people always tried to settle close to water. As the size of the settlements grew, it became increasingly difficult to get the water from the source - the spring, pond, river or lake - to the different dwellings. At first, people used open conduits - initially simple trenches, later stone canals. When the springs and sources were exhausted, aqueducts were used to carry water from the mountains into the towns. Some 300 years A.D., the Romans transported water from the Campagna into their capital and some of their impressive waterways can still be marvelled at in modern-day Europe.

Later, the open canals were covered over and used as closed conduits - and thus the pipeline was born. People were also quick to realize the benefits of closed pipes against open canals for removing waste water. Early pipe materials included wood and stoneware (fired clay), but also easy-to-work metals such as bronze, copper and lead. The first closed pipelines were made around 4,000 years ago of fired clay. The oldest metal pipelines date back to 200 years B.C., first made of bronze and later lead. Lead pipes were cast and chiefly used to Transport water. Copper pipes meanwhile were made from chased copper plate which was rolled and subsequently soldered together.

The advent of an economical method of producing large quantities of cast iron in the 14th century laid the foundation for the manufacture of iron pipes. Gunsmiths and cannon-makers were amongst the first to produce iron pipes. Cast iron pipes were used as early as the 15th century to carry water - some dating back to the 16th century are still in use today. Cast iron pipes also accompanied the development of a public gas supply network, for which compression-proof pipes were a matter of safety and therefore absolutely essential.

As more economical steelmaking methods were developed, an opportunity opened up for this material to be used for pipes. The first were forge-welded out of hoop steel, a method already known to gunsmiths in the Middle Ages. Around 1880, the invention of crossrolling by the Mannesmann brothers also made it possible to produce seamless pipes and tubes. With their thicker walls, seamless pipes offered greater stability at a relatively low weight. Oil-prospectors used such pipes to reach deeper reservoirs and by doing so were able to satisfy the growing demand for mineral oil which accompanied the early days of motorisation. The fact that mineral oil could be transported economically over long distances through a pipeline pushed up the demand for steel pipes even further. Soon, pipelines came to be the biggest market in this area, with demand reaching several million tonnes of welded and seamless pipes every year.

The crucial importance of how a pipe is made for the economic efficiency and environment-friendliness of industrial plant can be illustrated with the contemporary example of seamless boiler pipes with inner ribs. For years the power industry has been aiming to reduce fuel consumption and thereby cut CO2 emissions by stepping up efficiency. This can be done by working with higher operating pressures and temperatures. Consequently, plans have been made to set up new power plant in the first decades of the next century, which will run with pressure levels of up to 350 bar (today's maximum is 300 bar), at operating temperatures of around 700 "C (as opposed to 600 'C) and with efficiency increased from fts current 40% to 50%. Operating parameters of this kind can only be used for suitabie products and materials, of which seamless boiler pipes with inner ribs are one example. On account of their internal geometry, these pipes substantially improve the heat transfer between heating and the vapour phase on the inside of the pipe.

Pipes made of nonferrous metals and plastics Thanks to its good corrosion resistance, copper can be used to make pipes for the chemical industry, refrigeration technology and shipbuilding. Alongside their application for installation purposes, the usually seamless copper pipes are also used in capacitors and heat exchangers. For corrosive materials, low temperatures or stringent demands on the purity of the material carried by the pipe, Aluminium and Aluminium alloys are used in pipe construction. Meanwhile, thanks to its high resistance to many aggressive materials, titanium is well- suited to use in chemical engineering.

Plastics belong to the group of newer pipe materials. With the development of methods for producing plastics on an industrial scale in the 1930s, it also became possible to manufacture plastic pipes economically. By the middle of the 30s, plastics were already being used in Germany to make pressure pipelines. Among the chief advantages of plastics are their high corrosion resistance and a substantial chemical resistance to aggressive media. Moreover, the smooth surfaces mean that plastic pipes are not prone to incrustation, which can have a very detrimental effect on their conveying capacity. Pipes supplying drinking water are mostly made of polyethylene (PE) or polyvinyl chloride (PVC). Like ABS (acrylonftrile-butadiene-styrene copolymer) plastics, these two materials are also used for gas pipelines. Thermoplastic materials - alongside PE and PVC these include PP (polypropylene) and PVDF (polyvinylidenefluoride) - can also be used for industrial pipelines. Beyond these, PB (polybutene) and PE-X (cross- linked polyethylene) are also widespread in pipe-making. Plastic pipes find application in areas such as heating technology, shipbuilding, underwater pipelines (the crossing below a river floor from one bank to the other), irrigating and drainage plant, and well-building.

The right choice of material has a crucial bearing on the economic efficiency and safety of a pipe system. Materials therefore have to be selected according to the demands of each specific application. In steel boiler construction, for example, pipes must be made of steel with high temperature stability plus heat and scaling resistance, while special corrosion resistance is all-important in the chemical and foodstuffs industries. Meanwhile, the mineral-oil processing industry requires heat- proof or press-water-resistant steels for its pipes, gas liquefaction and separation, on the other hand, need materials which have special strength at low temperatures. This broad and highly diversified range of requirements has put a fantastic array of materials to use in pipe- making. Alongside the iron and steel, nonferrous metals and plastics mentioned above, these also take in concrete, clay, porcelain, glass and ceramics.

In addition to liquids and gases, solid matter, broken down, as dust or mixed with water in slurry form, is also pumped through pipelines. Gravel, sand or even iron ore can be conveyed in this manner. Pneumatic transportation of grain, dust and chips through pipes is also a widespread practice. Pneumatic tube conveyors, which similarly work with air, are another important mode of transporting solid matter.

Pipes may be several meters in diameter and pipelines many kilometers in length. At the other end of the scale are conduits with tiny, barely perceptible dimensions. One example of their use is as cannulas in medicine - a collective term referring to instruments with a variety of applications, including infusions, injections and transfusions. Their outer diameter ranges from over 5 millimeters to as little as 0.20 millimeters. Cannulas are made of high-quality grades of stainless steel, brass, silver or nickel silver (an alloy of copper, nickel and zinc, sometimes admixed with traces of lead, iron or tin), but also plastics such as polyethylene, polypropylene or Teflon. Often, different materials are combined with one another to produce the individual components. These tiny tubes must have extremely pronounced elastic properties. They may bend but under no circumstances snap. Their surfaces are often nickel[-plated and always highly polished, sometimes even on the inside. The best-known cannulas are hypodermic needles which, in their most common form as sterile disposable syringes, guarantee aseptic use without costly preparation for reutilisation.

Tubes for construction

No matter where we look in our cities today, we can be sure to see tubular steel constructions. They have become an indispensable element of modern building technology. Once again, we took the idea from nature: in tube-shaped straws, bamboo shoots, quills and bones, Mother Nature demonstrated the successful marriage of beauty and function. Yet these excellent static properties remained unexploited until the advent of welding technology made it possible to connect virtually all dimensions of pipes perfectly and with the necessary interaction of forces for use as construction elements.

As an extremely lightweight building element, steel tube combines high strength with low weight. Steel tubes are used as deck supports in shipbuilding, supports in steel superstructures and binders in building construction. They are used as tubular and lattice masts for overhead and overland transmission lines, for trains and trams, and for lighting. Bridges, railings, observation towers, diving platforms, television towers and roof constructions in halls or sports stadiums are all further examples. Steel tube is also a popular" building element for constructions in temporary use, such as halls, sheds, bridges, spectator stands, podiums and other structures for public events, supporting structures and scaffolding, from the small-scale for house renovation right up to building scaffolds.

In plant engineering, steel tube is used to make ladders, shelves, work tables and subframes for machinery and plant. Steel tube also found its way as a construction element into precision components for machinery and equipment. Shafts and rolls or cylinders in hydraulics and pneumatics are just two examples. Beyond these applications, a great volume of steel tube is used in the cycle industry, camping equipment manufacture, the furniture industry, vehicle and car making and the domestic appliances industry.

Be it on water, over land or in the air, the various modes of Transport would be lost without pipes & tubes. Pipes and tubular construction elements are to be found in ships, planes, trains and motor vehicles. A great variety of pipes and tubular profiles are used in car making, both in connection with the motor and with the chassis and bodywork sections. Most recent developments put them to a far more varied range of uses than before, from air suction pipes and exhaust systems through chassis components right up to side-impact tubes in doors and other safety features. One German car makers new lightweight concept takes as its basic subassembly a three-dimensional frame made up of complex Aluminium extruded sections joined together with the aid of pressure-diecast intersections.

Pipes in everyday use

We come into contact with pipes and tubes on a daily basis. It starts in the morning when we go to clean our teeth and squeeze the toothpaste from this tube, which is nothing other than a tube-shaped flexible container. We write notes with a pen, comprising one or more tubes with a smaller tube - the cartridge or refill - inside it. This is the modern equivalent of the quill, a pointed and split tube used in ancient times as a writing instrument and still used today for Arabic script.

We are surrounded everywhere we go and on a virtually constant basis by seamless pipe ＆ tube, whether at home, on the move or at work. They take the form of lamp stands and furniture elements in chairs or shelves, curtain rails, telescopic aerials on portable and car radios, and rods on umbrellas or sunshades. And when we water the plants or hang out the washing, tubes are our constant companion - on the watering can or the clothes-horse. Pipes Transport electricity, water and gas directly into our homes. Tubes protect visitors to the Duesseldorf Trade Fair Center from the rigours of the Rhineland weather. Pipe constructions are responsible for a pleasant indoor temperature and prevent the hall roofs from falling on our heads. Civil engineers and architects choose special section tube constructions for windows and doors in preference to other solutions. Tubes even have a role to play in our leisure time, providing us with bicycles, training apparatus and sports equipment.

Musical pipes

Musical instrument-making would be unthinkable without welded pipe ＆ tube. The tuba illustrates the connection particularly well: the name of this brass instrument is nothing other than the Latin word for tube. Other brass and pipe instruments also take the tube form. The reed used in a variety of wind instruments such as the clarinet, saxophone, bassoon or oboe is a flexible piece of cane which is fixed into the mouthpiece of the instrument or acts as a mouthpiece itself. Organ pipes also rely on the tube shape to create their sound. They are made of lead and tin, zinc or copper and are still crafted today according to a centuries-old Tradition.

CD stands in the shape of organ pipes make for an original link between two musical words. These CD stands are just under two meters in length, accommodate up to 50 CDs and, if required, can be supplied with interior lighting. Normally out of sight but critically important for good sound quality are the bass-reflex pipes found in loudspeakers. With the proper dimensions in length and diameter, these pipes help to reproduce low-pitched tones without any distortion as a result of unwanted flow noise.

Through squre pipe ＆ tube flows the lifeblood of progress and without them our lives would not be nearly as comfortable. They make everyday life easier, safer, more attractive, more varied and more interesting. More to the point, though, they have become indispensable for our existence, shaping the development of our lives to lasting effect in the past and undoubtedly continuing to do so in the future.