It is nearly impossible to gain total protection from explosions and bomb blasts. However, there are always some steps that can be taken to mitigate the impact of bomb blasts and minimize the damage caused by them. Over the years, manufacturers have tested several ways to fortify window systems, the most common of which is glazing.
There is a certain standard set in place to test and rate the glazing systems used in the U.S that enable your window systems to minimize the impact of bomb blasts. In this article, we will try to understand bomb blast testing standards and the rating of glazing systems in the U.S. so you can get a better understanding of air blasts and how they are tested in the U.S.
Understanding Bomb Blast Testing Standards
How Bomb Blasts Work — As Explained by Science
When a bomb blast happens, the first wave it produces travels at or above the speed of sound and destroys everything it touches. So if there is an explosion on the ground floor of a building, it would damage the first floor the most as the first wave accelerates by reflecting off the ground. In contrast, the higher levels of the building do not sustain much damage as compared to the first floor.
Moreover, the first wave also hits objects with increased pressure. But once this wave passes through the objects, its blast pressure decreases by milliseconds. The impact of the blast pressure reverses as the flow of air returns to the explosion location. This negative pressure then causes the windows that were pushed into the building by the first wave to pull outward. This pressure then reaches a “Peak Pressure” and starts receding.
You will also find the term “Peak Pressure” written on the blast test reports for window films. Peak pressure is used to describe the force that impacts a window. Moreover, you can also view the performance level of these window films across various standard levels in these test reports.
Blast Testing Standards
The blast performance standards for windows in the United States are two, namely ASTM International standard and General Service Administration (GSA) standard.
1. ASTM F2912 and ASTM F1642
These two are the standard specification and industry-standard test methods for glazing systems and glazing that are applied to airblast loadings. This test method offers a solid procedure for setting up the hazard rating for glazing, glazing retrofit systems, and glazing systems for an airblast loading. These hazard ratings are dependent on the performance levels of three tested windows.
2. GSA (General Service Administration)
The GSA standard for blast-resistant windows is for buildings and institutes that are run by or are the responsibility of the U.S. General Service Administration. These ratings are based on the performance of one window based on a rating scale. It tests these windows depending on how far the glass shards go into a room after a bomb blast. Although the parameters for the GSA and ASTM standards seem quite similar, they are not exactly the same.
Blast Testing Methods
Airblast testing is carried out in two methods; arena testing and shock tube testing. Arena testing is carried out outdoors by placing the target windows at a certain distance from the explosion. The impulse and blast pressure accuracy are really good. However, this method requires calibrated blasts. Both the negative and positive pressures are observed in this method as it is a true air blast and the only method that tests daylight applications.
On the other hand, shock tube testing is carried out in an indoor chamber under measured impulse and blast pressure conditions. There is no negative impulse in this blast like there is in an actual air blast. Moreover, an attachment system is used in this type of testing as there is only positive pressure.
In both of these testing methods, the testers try to get a target pressure and measure and report the acquired pressure, which can be slightly lower or higher than the target pressure.
How 3M Window Films Meet the Bomb Blast Testing Standards
The 3M safety and security window films are tested against all the bomb blast testing standards to offer ultimate protection. You can use these window films to fortify your buildings against accidental explosions and bomb blasts.
These windows films and attachment systems come with the highest level of safety. Combined with an adhesive or profile attachment system, the tough 3M Ultra Safety and Security films offer utmost reliability. Their attachment system connects the filmed windows to the frame to develop a solid shield that offers much better performance than window film-only systems. So you can rely on these systems to offer protection against forced entry, bomb blasts, explosions, and even earthquakes.
These window films come in two options; the 3M Impact Protection Profile and the 3M Impact Protection Adhesive. You can choose either of them by determining which one offers the best aesthetic appeal to your exteriors.
They are especially ideal for government facilities that are required to have blast hazard mitigation systems in place in their windows. In fact, the 3M Safety & Security Window Films and their Attachment Systems have been tried and tested against several official standards. They meet and exceed the performance parameters of various glazing types.
Final Thoughts
Not many window films meet today’s bomb blast testing standards. If you are looking for a robust window film and attachment system that gives you complete peace of mind, you can blindly trust 3M Window Films, which come with a warranty for residential use. So if your residence or commercial building is considered high-risk or it is located near a high-risk facility, you should have 3M Window Films installed to get ultimate protection against accidental explosions and bomb blasts.
