Safety and security are topics which are in the forefront of much design today. Here is some background information on this subject, excerpted from the Glass Association of North America’s Glazing Manual.

Blast Resistance
Blast-resistant laminates commonly are specified to mitigate injuries from flying glass resulting from an air-blast explosive.

All laminated glazing constructions provide some form of protection by holding the fragments together and limiting the likelihood that the glazing will come out of the window framing system. Several governmental agencies have specifications for the use of laminated glazing in buildings. When properly designed, framed, and anchored, blast-resistant laminates are capable of maintaining the integrity of the building envelope following an explosive and reducing interior damage. ASTM F 1642 Standard Test Method for Glazing and Glazing Systems Subject to Airblast Loadings is used to test laminated glazing for blast resistance. Designing blast-resistant glazing applications should begin with a risk assessment, and hazard mitigation must be addressed from a full system approach.

Burglar Resistance
Burglar-resistant laminates are covered by Underwriters Laboratories (UL) Standard 972, Burglar Resisting Material.
Burglar-resisting glass typically consists of two lites of glass bonded by a plastic interlayer which is resistant to penetration. UL-972 addresses smash-and-grab type burglaries and is considered a minimum-security product.

Bullet-resistant laminates are covered by UL Standard 752, Ratings of Bullet-Resistant Materials and National Institute of Justice (NIJ) Standard 0108.01, Ballistic Resistant Protective Materials. UL-752 consists of eight levels covering various weapons from handguns (Levels 1-3), high-powered rifles (Levels 4-5 single shot, Levels 6-8 multi-shot), to supplemental tests for shotguns.

This standard calls for no spalling (splintering) of the glass toward the “witness” side of the panel.

Bullet-resistant glazing is available in “all glass” configurations or in glass-clad polycarbonate make-ups. The thickness and configuration of the product will determine the ballistic protection.

Bullet-resistant glass is not always considered resistant to physical attacks. Consult the manufacturers for full details of specifications and test reports. A full threat assessment should be carried out before specifying the glazing.

Physical attack-resistant laminates are specified when architects or building owners require security protection from physical attack, either to keep someone out or, in the case of a jail, to keep someone in. The required performance must be specified. One of the following test procedures is usually specified and all contain various levels of attack-resistance for both ballistic and forced entry:

1. H.P. White Laboratories HPW-TP-0500.02 – Transparent Materials for Use in Forced Entry or Containment Barriers;
   
2. ASTM F 1233 Standard Test Method for Security Glazing Materials and Systems;
   
3. Walker-McGough-Foltz & Lyerla (WMFL) 30 and 60 Minute Retention – Ballistics and Forced Entry Test Procedure;
   
4. ASTM F 1915 Standard Test Method for Glazing of Detention Facilities.

Physical attack-resistant laminates consists of multiple layers of glass, multiple layers of polycarbonate, or multiple layers of glass and polycarbonate. The most common configuration is glass-clad polycarbonate.

This material is excerpted from the 2004 Edition of the Glass Association of North America Glazing Manual. Information about this publication is available at www.glasswebsite.com.

USG
© Copyright 2006 Key Communications Inc. All rights reserved.
No reproduction of any type without expressed written permission.