Bullet Resistant Glass: Explaining the UL Rating System
Bullet resistant glass is designed to stop projectiles without shattering, absorbing their energy and retaining the bullet. Whether the glass succeeds in safely stopping bullets or not depends on several factors, namely: the material and architecture of the glass; the severity of the impacting force and the projectile material; and the number of subsequent impacts. Guaranteeing the specified level of protection requires a testing methodology that can reconcile each of these dynamic factors.
So, how is bullet resistant glass tested and rated? In this blog post, Armortex introduces the UL rating system and outlines some of the rating levels in detail.
What is the UL Rating System?
The UL rating system is a series of tests established by the Underwriter’s Laboratory (UL), a not-for-profit organization focussed on enhancing public safety by founding sets of standards for various products. This organization developed the most widely-accepted set of quality standards for bulletproof glass and is one of few Nationally Recognized Testing Laboratories authorized to perform safety testing by the Occupational Safety and Health Administration (OSHA).
Eight different levels of ballistics resistant glass have been established by the UL, each capable of withstanding security threats of different magnitudes. A brief explanation of each level follows:
- Level 1: Refers to bullet resistant glass able to withstand fire from small caliber handguns. It must be able to resist a minimum of three 9mm FMJs traveling at a minimum velocity of 1,175 feet per second (f/s)
- Level 2: Defines bullet resistant glass designed to withstand fire from larger caliber handguns. It must withstand at least three shots of .357 magnum soft points traveling at a velocity of 1,250f/s.
- Level 3: Refers to bullet resistant glass that can withstand a minimum of three shots of .44 magnum rounds at a velocity of 1350f/s.
- Level 4: Represents a step-up in terms of ballistics resistance. It defines bullet resistant glass that can withstand at least one shot from a .30 caliber rifle with a minimum velocity of 2540f/s.
- Level 5: Covers bulletproof glass designated to withstand at least one 7.62mm rifle FMJ with a velocity of at least 2750f/s.
- Level 6: Is a direct improvement on Level 1, designed to withstand at least five 9mm rounds traveling at an elevated minimum velocity of 1400f/s.
- Level 7: Defines bullet resistant glass designed to withstand multiple hits with 5.56 rifle FMJs with a minimum velocity of 3080f/s.
- Level 8: Designates the highest level of protection available in bullet resistant glass. This level is tested to withstand at least five shots from a 7.62mm rifle.
Level 3 bullet resistant glass is preferred for larger facilities where threat levels are typically more severe. Police stations and government facilities routinely use UL Level 3 rated products, though they are also being increasingly adopted at scale for school security.
Levels 4+ offer comparative levels of protection and are built to withstand fire from assault rifles and automatic weapons. These are implemented in the highest risk applications where the added material costs are justified by the level of threat. Military bases and government buildings typically utilize products rated UL Level 4—8.
Bullet Resistant Glass from Armortex
Armortex is one of the foremost suppliers of bullet resistant products in the U.S. We offer ballistic-resistant windows comprising the highest quality silicate and polymer glass materials, with a choice of framing solutions to ensure comprehensive protection regardless of your application.
If you would like to learn more, please do not hesitate to contact us directly.