Blast Protection Standards and Independent Testing
Several years ago, the General Services Administration (GSA) mandated a universal standard for measuring the level of blast protection. The GSA developed criteria for evaluation of acceptable levels of protection for the glass fragment hazard. This criteria is part of the comprehensive security criteria (GSA Security Criteria, Final Working Version, January 1997) developed by the GSA which includes physical security, electronic security, and many other criteria for blast considerations. The GSA has indicated a preference, but not a requirement, for open-air high explosive testing rather than shock tube testing. This is because current shock tube testing methods cannot adequately emulate air blast waveforms from real explosions and tend to be over-energetic at the same peak blast pressure level versus real explosions.*
*Some text taken from independent testing firm, Applied Research Associates, Inc., 1/98
GSA Protection Standards
|Condition||Description||Exterior to Structure||Interior to Structure||Hazard Level||Protection Level|
|1||Glass not cracked, fully survived and/or fully retained by frame, and no glass fragments either inside or outside structure.||None||None||N/A||Very High|
|2||Glass may be cracked but is retained by the frame.||Yes||Yes – land on floor no more than 10 ft from window.||Very Low||Very High|
|3||Glass failed and not fully retained in the frame.||Yes||Yes – land on floor more than 10 ft from window and impact a vertical surface not more than 10 ft behind window below a height of 2 ft.||N/A||High|
|4||Glass failed and not fully retained in the frame.||Yes||Yes – land on floor more than 10 ft from window and impact a vertical surface not more than 10 ft behind window above a height of 2 ft.||N/A||Medium|
|5||Glass fails catastrophically.||Yes||Yes – land on floor more than 10 ft from window and impact a vertical surface not more than 10 ft behind window above a height of 2 ft.||High||Low|
ARA’s Major Findings
This test series showed that the 3M™ Scotchshield™ Ultra series of security window films provides significant benefit in mitigating window glass fragment environments in blast. Per the GSA criteria, the 4 mil ULTRA400 (.004 inches) and the 6 mil ULTRA600 (.006 inches) 3M™ films performed to the required levels for many of the configurations tested. Both products performed well up to blast pressures as high as 9 psi. Many configurations tested performed to the required level of protection for GSA Level C buildings at the maximum design load. Several other configurations performed to the required level of protection for Level D buildings up to 9 psi and for an impulse of about 50 psi-msec.
In its strongest configuration, 3M™’s ULTRA600 achieved a Very High protection level and a Condition 2 on the GSA rating scale when tested with a standoff distance of 121 feet and a peak pressure of 9 psi.