Types of fire-resistant glasses

The increased use of glazing in buildings, together with building code requirements in the fire-rated glass sector which have seen rapid changes, have lead to the development of new types of fire glasses.

Generally, any type of glass that can withstand the fire test and therefore resist passage of smoke, flames and hot gases, is considered "fire-resistant glass". These glasses are then further categorised and rated according to special criteria. Typically, the rating is based on how long a particular type and size of glass will withstand fire. Classifications range from 20 minutes up to 3 hours. Ordinary flat glass cannot withstand extreme temperatures, and breaks at around 120° C. Fire-resistant glass must be able to withstand 870° C for a selected period of time and remain in its frame. Immediately following this extreme heat, the glass is exposed to ?The Hose Stream Test?. In this test, water is used to rapidly cool the hot glass to test its ability to withstand thermal change. The purpose of this test is to test a real situation in which water from a sprinkler system shatters glass intended to function as a barrier, and thus permits smoke and fire to spread and escalate to the next level. The three most important factors in connection with the choice of fire-protection glass are: - type of protection (class E- and class EI) - duration of protection (e.g. 15, 30 or 60 minutes), - frame construction to be used (wood, aluminum or steel). Class E involves protection against smoke and flames while class EI also offers protection against fires spreading heat radiation. On the market today they are several fire-resistant glass products such as wired glass, ceramic glass, fire-rated tempered and special laminated glass.

article source http://www.glassonweb.com

Today’s challenges of automotive glass manufacturers

Automotive glass manufacturers are forced to face great challenges daily. Especially now since world financial crisis had almost immediate impact on the industry. The slowing economy drives the new vehicle sales down with out exception in each continent. To Remain competitive, more than ever now all manufacturers from largest multinational corporations to smaller private companies are seeking ways to cut costs, improve efficiency and production yields – at least they should be, by now.

Ever rising energy prices are making each windscreens production cost higher and when we add on top of this all the costs arising from waste pieces, used working hours, and possibly extended development periods, the margin per piece simply comes smaller and smaller. Without continuous efforts to boost up the yield, productivity, efficiency, and quality, company will end up losing ground to its competitors. Well trained, professional and committed staff is a key factor when companies fight their way through these rough times. THE PROCESS From raw glass warehouse, to cutting table, grinding, washing, long pair powdering and short pair to printing, short pair is dried and finally glasses are paired again. After this so called “cold-end” of the process is done and the glass is half way in the process chain. It is amazing how much these processing methods still vary today. It is common to see glasses hand cut and separating powder applied manually while in the other hand larger more developed companies use completely automated production lines with robots and automatic measuring. Although these companies are set to aim different markets, both can make profitable business. With out any deeper knowledge on the cold-end part everyone can understand that a lot can be done wrong and many to cut costs and improve efficiency. Automatic quality control monitoring is available for the manufacturing lines, but due to the costs the quality is still monitored by the operators. From these processes grinding and powdering can cause breakages and defects later, in and after bending process. Therefore it is important to monitor these processes carefully. After the “cold-end” the process chain continues with bending the most demanding process of the complete chain. After bending follows pvb assembly, vacuum and autoclaving. This article will focus more on the “hot-end” part of the process chain. MANUFACTURING CHALLENGES - Bending the most important part of the process Every day larger and more complex shapes in car windscreens come more common. Although every part of the process play their important role in the final product, it is clear that bending is the most important and demanding part. Without successful bending results the complete process fails. So called cielo and panoramic type windscreens with deep cross curvatures, tight wing shapes and small installation angle, together with thin, coloured, glass pair combinations create an “equation” that needs careful and professional care while it’s been developed into production. Bending these difficult windscreens with basic gravity bending furnaces is everything else than simple. The key issue will be – How to achieve perfect optical quality. Challenge is obvious, even to meet the optical requirements of the ECE 43 regulations and it is common that the car manufacturer has its own standards. These manufacturer standards have a tendency to be far more demanding than the ECE optical regulations. Hand in hand with this optical challenge comes the complex shape. Deep cross curvatures are sometimes some what tricky to handle. The “profile” of centre section of the glass easily contains “flat” or “reverse” parts. In other words the cross curvature is not smooth and continuous, as part or parts of the windscreen is left “flat” or has “reverse bending”. These “flat and reverse” areas cause problems in “wiperbility” and in worst case these defects will cause reflections on the optical examination. Due to the challenging characteristics of the windscreen and quality requirements the bending trials can get uncomfortable while the perfect heating configurations and tooling settings are being searched for long periods of time and often without any encouraging results. After a while the work can come into a halt. Correct heating configuration and advanced tooling are highly important, but it is also necessary to realize that good optical quality cannot be reached if the process chain from cutting until final inspection is not in order. The latest model serial gravity bending furnaces are equipped with wide range of features, but still the challenge is real. The biggest advantage on new furnaces is the well improved heating element controls and endless possibilities of adjustments. In fact so many that an average shift operator does not know half of the parameters and the functions behind. Older furnaces have their limits when it comes to producing the windscreens for latest car industry innovations, and we are not talking only about the physical limitation set by the chamber size. Coloured, thin glass pair combination and a complex shape can prove out to be impossible to manufacture without up to date machinery. Unfortunately investing into a new furnace can be too expensive. Similar challenges are faced with coach, special vehicle and bus windscreen manufacturing. Biggest challenge for this segment of windscreens is the wing and corner shapes. Today most of the single chamber and serial furnaces for larger windscreens are equipped with bottom heating and position/out put power controls. These technical features enable faster and uniform heating for both short and long glass pair and a precise heating radiation control only to the areas where the radiation needs to be applied. Bottom heating further eliminates possible optical defects. Large windscreens with long and tight wing shapes together with deep cross curvature are difficult to bend to the final shape. Deformations on edge shapes and reverse bending are common problem when the glass has been forced to its shape. To achieve competitive results advanced mould tooling is very important. Advanced mould tooling allows perfect control of the windscreen from the beginning of the bending process until the very end. With different mechanical solutions the mould and glass can be controlled so that no external manipulation of the glass is necessary. Such control of the glass and mould eases reverse bendings and shape deviations on the corner areas. Generally, with both; serial and single chamber furnaces, complex bus and special vehicle windscreens are bent manually using only the basic automatic functions such as automatic heating element configuration during the bending and final bending. Other functions weight controls, slight adjustments on temperature balance and finally release to cooling (Glass Ready) are all controlled by the operator(s) during the process. Manual operating is time consuming but in some cases cannot be avoided, simply because the technology available today does not make it possible. Since the process is controlled manually it is obvious that certain level of skill is a must to successful operation. The bending is very unforgiving, and one mistake can be fatal to the end product. Well trained and committed staff is major factor in this process and the yield levels and quality can be improved to a completely new level with continuous and efficient development of the bending practises QUALITY - a true strength ECE 43 regulations determine the basic guide lines regarding the checks on conformity of production, but it leaves a lot for the manufacturer it self to decide how to measure and control the end product. When compared the manufacturers ARG windscreen manufacturing quality control measures vary widely from next to nothing to basically thorough 100 % inspections. For example: Some companies are checking all windscreens immediately after bending with the checking fixture and document the shape and size variations carefully while others still are not using no checking fixtures at all. In OEM segment the practice does not vary so widely although clear variation on quality control measures is still there. Strict quality control measures after each process are easy way to improve the yield levels and save costs when only the good parts are processed. Once again the production line staff is in a key role – they must be committed to the perfect quality idea. INDEPENDENT EXTERNAL VIEW – way to easier solutions? In every aspect of the business, companies are using consulting, coaching, training and advising when their own internal development and technical departments face a situation when there’s simply no new ideas and the work comes to stand still. Most of the times the external view is sought even before the actual stand still situation is faced. In these situations external professional view, can probably pin point the weakest spots and determine worst “reefs” to be avoided. Problems can be caused simply because the matters are looked from “too close proximity” and instead of seeing the complete picture, everyone is focused into one minor detail, “thinking inside the box”. Thinking outside of the box normally generates innovative and novel ideas. Sometimes neutral external “variable” can change a lot. Broader view, different approach, professional experience, and purely neutral opinions based only to the facts gathered, can lighten up the situation for all, in completely different perspective. Doesn’t really matter if it is a technical problem or matter of working practises – the “external variable” can be a way to easier solution. In technical problems the working pattern is very much like doctor and patient relation. The reasons are sought according to the patient’s report of the symptoms. Doctor examines the process and after analysing the observations he explains the cause and consequences and suggests possible treatments. All this is done under professional confidentiality. Since the automotive windscreens manufacturing process chain still contains a lot of “manual” and “automated manual” work it is clear that the skills and commitment of the manufacturing staff play a crucial role on the continuous development. Both multinational corporations or private companies targeting the local markets need “tools” to overcome and improve their daily practises. Efficient and necessary “tool” can be change of attitude, practical training, technical advising or possibly new machinery, but sometimes hiring help out side is necessary to define the correct solutions. article source http://www.glassonweb.com

What makes glass transparent?

Glass is something we use every day, a transparent material produced by melting a mixture of sand, calcium, oxide, and other raw materials and then cooling the resulting product. But have you ever wondered what makes glass transparent? Why can we see through window and not through the frame that enclose it?

In general most liquids and gases like water, air, natural gas, cooking oil, or rubbing alcohol are transparent, while solid materials like wood, metal, ceramics, etc. are opaque. That is because of a difference between the molecular structure of solids, liquids and gases. When a substance is in its solid state, molecules are ordered in a regular lattice just like bricks stacked neatly on top of one another, being virtually impenetrable for light waves. The molecules of an substance in the liquid stage are disordered and are not rigidly bound. This causes the disordered stacking of the molecules, creating gaps and holes that allow portions of light waves to pass through. The greater the gaps in molecular organization the easier it is for light to pass through. As glass in neither liquid nor solid, because its molecules are motionless (like a solid) but random in configuration (like a liquid), glass exists in a solid yet transparent state.

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Why a hose stream test is critical for testing fire glass

The options in fire-rated glass have expanded greatly in recent years. Where architects and designers were once limited to traditional wired glass in relatively small sizes, today they can choose from a range of glazing that offers superior fire protection and the chance to incorporate entire walls of glass without compromising safety.

This is no small feat: To achieve a fire rating of more than 20 minutes, heated glass is subjected to a mandatory hose stream test as specified in test standards such as the National Fire Protection Association’s (NFPA) Standards on Fire Test for Window and Glass Block Assemblies. While some have questioned the ongoing necessity of the hose stream test, the NFPA standards clearly state: “The hose stream test provides a method for evaluating the integrity of constructions and assemblies and for eliminating inadequate materials or constructions. The cooling, impact, and erosion effects of the hose stream provide important tests of the integrity of the specimen being evaluated.” Why should architects, glaziers and building code officials be aware of the importance of the hose stream test? Because one manufacturer now sells a 60-minute “fire-rated” product that does not and cannot pass the mandatory hose stream test. To the unsuspecting eye, a 45- or 60-minute fire-rated label on the glass that says “…without hose stream…” may not raise suspicions – unless you know that the hose stream is a mandatory procedure required by North American test standards. To selectively decide what portions of required test procedures one chooses to complete can be dangerous. Fire-Glass Testing The hose stream test is part of a series of tests that begins with heat testing of the glass. Manufacturers seeking a fire rating take their products to an independent testing facility, such as Underwriters’ Laboratories. The lab installs multiple pieces of the glass in a frame and wall assembly, which is then placed in a large furnace. A fire is then ignited on one side of the widow assembly, with temperatures attempting to replicate a “real world” fire. Following a standard time/temperature curve, at five minutes temperatures approach 1,000 F. and are nearly 2,000 F. at 180 minutes. The length of time the glass remains intact in the furnace will correspond to the final fire rating it receives (ranging from 20 minutes to 3 hours). The goal of this testing is to determine how long the glass can remain in place and be expected to act as a barrier to a real life fire. If glass fails under the intense heat and vacates the frame, the flames and deadly smoke will be free to travel throughout a building. If glass successfully survives the fire test and the manufacturer is seeking a rating greater than 20 minutes, the glass is immediately put through a second type of test. While the glass and framing system is still hot from the furnace, it is sprayed with water from a fire hose at a pressure of at least 30 PSI. Most glass cannot tolerate drastic temperature differences such as this. If one area of the glass and framing system is hot while another is cool, it creates stress on the glass, known as thermal shock. Since part of the glass is expanding and part is contracting at the same time, the glass will shatter and vacate the frame. The hose stream test is a critical way to measure how glass will respond to temperature differences. The glass must remain intact in order to pass and offer protection. Interestingly, it doesn’t have to be a fire hose to prove the point. One manufacturer tested a 20-minute rated product with a simple garden hose. While the hot glass was able to withstand approximately 1,500 F., it quickly shattered when the light spray was applied. Continuing Need for Hose Stream Test Why is the hose stream test important? In the case of a real world fire, there’s a good chance glass and framing systems that have been exposed to the heat of flames will also be subjected to water from a fire hose, sprinklers or fire extinguishers. If the glass can’t withstand thermal shock, it will fall out of the frame, leaving an opening for fire or smoke to spread. In the United States, all fire-rated glazing products with ratings greater than 20 minutes are required to pass the hose stream test (Canada requires the hose stream test for all ratings). Building and fire codes are very clear on why the hose stream test is critical, and in recent years, proposals to eliminate the test have been soundly defeated. Last year, the manufacturer marketing a product that cannot pass the hose stream test sought to eliminate the hose stream test requirements from two portions of the fire-rated glass test standards in the International Code Councils’ (ICC) building safety and fire prevention codes. The ICC’s Fire Safety Code Development Committee, comprised of code officials, fire marshals and other experts, rejected these proposals after careful review of the issues presented in open public hearings. In its rejection of one of the proposals, the Committee stated that removal of the hose stream test requirement “…would reduce the level of life safety which the code has generally required and provided.” In its decision on the other proposal, the Committee noted that the issue has been debated a number of times and that “it has always been defeated.” (2006 ICC Public Hearing Results, FS121-06/07 and FS107-06/07). By its actions, the ICC has repeatedly validated the importance of the required hose stream test for life and property safety. When choosing fire-rated glazing materials, it is critical to make sure that the product in question meets or exceeds all the testing standards. Otherwise, you may be taking a serious risk or increasing your liability. For openings with fire ratings of greater than 20 minutes, always insist on glass that has passed the mandatory hose stream test, and beware of products that acknowledge they have not passed the required test. There’s no need to compromise when life and property safety could be at stake. About the author: Jerry Razwick is founder and president of Technical Glass Products (TGP), a distributor of specialty glass and framing as well as architectural products. He has been a glass factory agent in foreign and domestic markets for over 25 years. Mr. Razwick has served on the Industry Advisory Committee for Underwriters Laboratories, Inc. and is an active member of AIA, CSI, NGA and GANA

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Windows of the future

We spend millions of dollars every year to heat our homes and businesses. That is why it is so important to understand the role that windows play in how buildings use energy. In older homes, windows are often one of the largest sources of heat loss in winter due to their low insulating ability and high air leakage rates. Windows are also generally the major source of unwanted heat gain in the summer. As a result, windows are typically net energy losers, and can be responsible for 25 to 50 percent of the energy used to heat and cool homes. However, improved windows, combined with proper consideration of their placement and other details, can result in windows that provide a net energy gain.

Windows Windows were once little more than holes cut in walls to let light and air into rooms. Today they bring beauty and light, warmth and cooling breezes into homes while providing a sense of openness and space. On the down side, windows can also let in the winter chill or the summer heat. They can make a home drafty, uncomfortable, and energy inefficient. Fortunately, modern windows make the most of the benefits of windows while minimizing the drawbacks. Single-pane glass has been replaced by multi-panes separated by insulating materials. Frames are made of new, more energy efficient materials. Even the glass itself has been coated to reflect heat. Windows of the future New technologies are producing increasingly energy efficient windows. Already on the market are “super-windows”, boasting triple layer designs, with two low-E coatings and spaces filled with mixtures of argon or krypton gases. A new generation of windows, however, is being called “smart windows” because they adapt to changing conditions. A few “smart windows” are already commercially available, and others are being developed in research labs. These windows change properties - like their shading coefficients and visible transmittances - in response to either an electric charge or an environmental signal such as a change in light level. Depending on the mechanism that initiates the change in the window, these “switchable glazings” fall into four categories: electrochromic, liquid crystal, thermochromic, and photochromic. By GlassOnWeb editorial staff Photochromic Windows: See The Difference Sunlight Reactive Thermo Windows are the ultimate “smart” window.  They are perfect for any application, architectural or residential. Photochromic glass automatically changes from a clear glass to a tinted glass with the rays of the sun.  There is no electricity or knobs required.  As the sun sets, the glass will lighten up returning to it’s clear state.  This will continue each time the sun is shining on the glass without fatigue unlike film tints and coatings.  It also costs a fraction of the price of other smart windows currently available on the market. Other glass reflects the harmful ultra violet rays that go back into the Earth’s ozone and are a great contributor to the global warming problem.  Photochromic glass absorbs the UV rays helping to protect our planet.  In doing this, it reduces the heat transferring into the building and reduces energy consumption and air conditioning costs. In architectural applications, the automatically tinting glass will create privacy on sunny bright days.  It will also protect expensive office furnishings with it’s 100% UV protection and stop the glare on computer screens and projectors.  It can be made in a variety of colours making each application unique. In residential applications, homeowners will be able to enjoy the sight out of their windows, protect their furnishings, and save on their energy costs all without curtains or blinds. With Sunlight Reactive Thermo windows, as the glass changes from light to dark with the sunlight, you can see the difference. For more information Please visit our website at:www.photochromicwindows.com By Christopher Crawford

World Demand for Flat Glass

According to a study from the Freedonia Group, production of flat glass is projected to increase 5.2 percent per year through 2008 to 48.3 million metric tons, of which around 34 million metric tons will be high quality float glass.

Construction markets will grow the fastest based on expanding global fixed investment: consequently, demand in the already dominant architectural glass sector will register the best gains.  The market for architectural glass is forecast to grow 5.4 percent per year through 2008 to US$53 billion: it will benefit from the greater use of value-added glazing products (such as laminated, tempered, mirrored glass, and, above all, double-glazed insulating glass units, which have become more and more popular in developed countries).  Asia will continue to offer strong annual gains, with growth especially strong in China and India. The US market for fabricated flat glass is forecast to outpace the global average, although actual gains in metric tonnage and square meters are expected to remain slightly above the average. Western Europe will continue to post the weakest sales growth, hindered by below average economic growth.  article source http://www.glassonweb.com

Windscreens Go Deeper, Wider, Steeper, Spherical

Breaking new ground with designs that are original and appealing is a daily challenge for car designers. One limitation on their creativity may be the constraints placed by the materials used in the design.

New glass technologies have brought significant advances in design; windshields have gone from being flat to curved, and now they can be spherical with wrap-around corners. Many practical issues still pose a challenge; visibility during the day and at night, comfort and safety, to name a few.  As a result, car designers today are including more and more glass in their cars. They are looking for aerodynamic efficiency, driving comfort and safety, as well as optimum structural stability and an attractive appearance. This has led to higher and wider windscreens, and steeper inclinations. And more glass overall in the car body.  TECHNOLOGY  For deep sags (> 30 mm), it has almost been the rule to use a press bender. This is certainly justified in long OEM series, but for short OEM series and replacement windscreens, it reduces manufacturing flexibility. Glassrobots has designed its innovative, reliable TFA FuzzyBend™ range of windscreen bending furnaces to be flexible enough for short and long runs in OEM and ARG production. With the new TFA 3evolution™ furnace, windscreens with sags of up to 32 mm are also produced with the reliable Glassrobots gravity bending control method. Using the TFA 3evolution™, it is possible to manufacture these windscreens, which manufacturers used to think required a press bender. Windscreen manufacturers can then decide whether they do short, long or replacement series. With the TFA 3evolution™, they at least have the right furnace.  The tooling for a press bender is also very expensive, which makes it uneconomical and unsuitable for producing replacement windscreens. Since more and more new windscreen models are being produced, it was time to design a reliable and flexible furnace for this ARG market. Complex, wrap-around corners, increased cross-bending and larger glass sizes are typical features of modern windscreen design.  The outstanding, distortion free quality and dimensional accuracy of the end product, as well as the higher capacity, derive from the following innovative features of the TFA 3evolution™ furnace:  • New enhanced bending programme based on percentage control of heating elements with the proven and patented FuzzyBend™ control system  • Bottom heating elements with individual control for different models  • Special second level heating zone  • Customised heating elements for making the most demanding windscreen shapes  • Optimised arrangement of moving parts  All this is backed up by the experience and proven technology of Glassrobots, such as:  • Vertically Adjustable Heating Elements, VAHE™, to focus heat in difficult areas in the bending section  • 5-part heating elements in the bending sections, instead of the normal 3-part elements  • Temperature Balancing System, TBS™, consisting of an extra pyrometer in the bending sections, guarantees symmetrical heating. The glass temperature is measured systematically and if variations are detected, the control system automatically adjusts the heating pattern.  • Side Heaters enhance the heating of the side areas. They are normally installed in the pre-bending and bending sections.  • MirrorPattern™ (patent pending) eliminates the negative effect in mixed production of thermal inertia from the heating pattern for the previous glass.  • GlassButler™, remote diagnostic software that enables our technicians to be in direct contact via a modem link with the client’s process computers.  • Condition Monitoring and Maintenance System, CMMS™, a preventive maintenance feature that minimizes downtime and maximizes hours of operation.  RECENT DELIVERIES  Trakya Cam Sanayii A.S. Oto Cam Fabrikasi, a member of the Sisecam Group in Turkey, acquired its second car windscreen bending furnace from Glassrobots in just two and a half years. Sisecam is the biggest glass producer in Turkey. The Sisecam Group, one of the first public enterprises in Turkey, is quoted on the Istanbul Stock Exchange.  Gilan Glass Industries, Iran, is one of the largest OEM suppliers in Iran. They have one plant operating in Rashd in northern Iran. Capacity requirements have increased, and GGI is building a new plant in southern Iran. To better serve OEM car suppliers, GGI chose the new Glassrobots furnace, with an option for a second one.  The innovative details characteristic of Glassrobots furnaces were the main reason why these clients chose aGlassrobots furnace. And there are more to come, with windshield manufacturers queuing up for this fantastic product.  FUTURE INNOVATIONS  Much has been achieved, but even more remains to be done, to satisfy the ever-increasing demands of windscreen benders, or ultimately the car designers and makers. Future models will probably make even greater demands on the bending and laminating process. The use of solar-control glass, heated windscreens, integrated antenna systems, advanced display systems etc. is becoming more common, but research on these and other issues is going on all the time.  It is not just windshields that are undergoing considerable changes in design. Windscreens today may even continue directly into a roof window that is also laminated. Some car models now have laminated side lites. These provide better sound insulation, improve security against break-ins and safety in roll-over accidents, and of course give a wide range ofcolour options. But they cost five times more for the carmakers.  In order to meet future requirements and develop the new technology for them, the windscreen processor and furnace manufacturer have to work together and come up with new ideas to give them an edge over the competition. The key factors in success will continue to be cost efficiency, process quality and control and, above all, product quality.  article source http://www.glassonweb.com

Photos: Glassrobots Oy Last review: July, 2008