Volume 7, Issue 4, July-August 2003
Educating Customers On Security Films
by Nick Routh
Safety and security films have been a growing part of the film industry for some time and this growth is likely to continue, due to the uncertain times in which we are now living. These films are very similar to energy control and automotive films in structure except that they are thicker and have a highly aggressive pressure-sensitive application adhesive. Safety and security films are usually used to improve the performance of the glass for protection against human impact, bomb blasts, natural disaster, intrusion or seismic activity.
In many cases, the applicator on the job is the one who will be looked upon as the “expert” explaining film performance. Since the responsibility of educating the customer may fall on you, it would be beneficial to have some general knowledge of the performance requirements for the above topics. Below, you will find a short general description of the tests required to determine the performance of the material when used for any of the aforementioned topics.
Human impact standards were developed in the early 1970s to reduce the injuries to people who impacted glass in homes and buildings and caused it to break. The two main standards in the U.S. that deal with human impact are the American National Standards Institute (ANSI) Z97.1 and the Consumer Product Safety Commission (CPSC) Code of Federal Regulations (CFR) 1201, category II. The ANSI Z 97.1 standard is most commonly used for residential applications while the CPSC CFR 1201 is more often found in commercial applications for glazing. The ANSI Z 97.1 standard usually requires a 100- and 150-foot-pound impact on the glass while the CPSC CFR 1201, category II, requires a 400-foot-pound impact.
Although both these standards can be tested at the same impact levels, the two mentioned above are used most commonly. These standards are the points of reference that require the use of tempered glass or the addition of film on annealed glass to bring the glass into compliance. If film is used to bring sub-standard glass into compliance, it must be accompanied by a compliance sheet and the necessary labeling to be applied to the treated glass.
Glazing that is resistant to hurricane impact has garnered a considerable amount of attention since Hurricane Andrew struck south Florida in 1991. The damage caused by Andrew led to significant code changes for new construction at county and state levels, not just in Florida, but also in most coastal states. These code changes require the glass and glazing structures to pass missile impact and cycling tests, which simulate a hurricane environment. The severity of the testing will depend upon two aspects: the height of the structure and the location of the structure, along with its expected wind speed for that area. The height of the structure will determine the size of the missile (i.e., whether it will be large or small). Structures at ground level and no higher than 30 feet above ground will be subjected to the large missile and structures above 30 feet will be subjected to the small missile.
These codes are variable and you should check your local building code requirements for impact-resistant glazing. Security film can provide a significant level of protection, but cannot meet all the code requirements. Films have been tested that meet the lower wind speed (90-100 MPH) for large missile and cycling but they must be anchored to the frame. Films have also been tested to meet the highest wind speed requirement (> 150 MPH) for small missile and must also be anchored to meet the cycling requirement. Bear in mind that retrofit film applications do not have to meet new construction codes. However, be certain to require test results for the film performance, should you want to use film to bring existing glazing up to a specific code.
Safety film has long been used to enhance the performance of glass in areas where earthquakes often strike. In an earthquake, the glass is broken by compression due to the twisting or “racking” of the building. Using safety film, glass will break catastrophically, but the shards will be held onto the film, thereby reducing the possibility of injury. Usually, a simple “daylight” application of a 4-mil or thicker film will suffice for this protection.
Almost any film will be helpful in thwarting the efforts of the “smash-and-grab” artist since he has a very short time limit. If the glass breaks but stays in place, he will leave and usually will go to an easier target. However, when his more serious counterpart takes on a piece of glass, it is going to have to be protected to a higher degree. These fellows will cut through film or push it out from the corner to gain entry. In order to offer a significant level of protection, you are going to have to use thick films, 10 to 14 mil, and anchor the film on all four sides.
The predominant test for determining the performance of applied film on glass for intrusion is the Underwriter’s Laboratory (UL) 972 for burglary resistance. This consists of a 5-pound steel ball falling from ten feet and striking the glass five times. No penetration of the ball is allowed.
The most accepted test for determining the performance of glazing in a bomb-blast environment is the General Services Administration (GSA) Test for Airblast Loading on Glazing and Glazing Structures. This test is based on producing a known pressure on the glass as would happen in a bomb blast. The pressures where safety and security films have shown a very good protection level are 4 (pounds per square inch) PSI and 10 PSI. These pressures can be produced either in an “open-air arena” in which an explosive mixture is detonated, or in a “shock tube,” in which air pressure is used. After the pressure is exerted upon the glass, the response of the glazing is graded by how far the glass traveled into the ten-foot deep, closed structure. The grading system is as follows:
|1||Glass neither breaks nor cracks|
|2||Glass breaks but no pieces fall beyond the sill (5”)|
|3a||Glass breaks but no pieces fall beyond 1 meter (3.3 feet)|
|3b||Glass breaks and pieces fall more than 1 meter but less than10 feet|
|4||Glass strikes the back wall but no higher than 22 inches|
|5||Glass strikes back wall above 22 inches|
A daylight application of a 4-mil film can have a performance condition of 3 or 4 at the 4 PSI level, which would be considered at worst a low hazard. A heavier, anchored film may have a performance condition of 2 at this same pressure. For the 10 PSI level, very heavy films, such as 12 to 14 mils, mechanically anchored on all four sides, are required to yield a performance condition of 2 or 3.
If you have a basic understanding of what is required to meet these tests, you can provide your customer a valuable service in selecting the correct film for his needs. You can then verify your choice by contacting the manufacturer to provide the required test data. Safety and security film can become an important addition to your company’s repertoire if you take the time to learn what to use, where to use it and how to best express both of those needs to your customers.
Nick Routh is the government sales manager for Bekaert Specialty Films, which is based in Clearwater, Fla.
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