NCJ Number
132430
Journal
Security Management Volume: 35 Issue: 9 Dated: (September 1991) Pages: 121-122,124-125
Date Published
1991
Length
4 pages
Annotation
This article reports on tests that compared the penetration risks and consequences of monolithic and laminated glazed glass.
Abstract
Security glazing refers to a wide range of glass products that share the common attribute of one or more interlayers of energy-absorbing, high-performance plastic. Standard laminated glass consists of two or more plies of glass bonded by a polyvinyl butyral plastic interlayer. Laminated security glass products can be specified for virtually any application, regardless of the architect's requirements for heat transfer, acoustics, visibility, or aesthetics. The tests focused on the most common types of threats: blast effects, whether accidental or the acts of terrorists; various caliber ballistic attacks against a variety of window panes; forced entry through glazings; and electronic invasions. Test results indicate that although architectural monolithic glass meets some requirements for accidental damage, common thicknesses for such glass offer little or no resistance to forced entry, ballistic attack, or electronic invasion. Such glass becomes part of the weapon when it shatters under blast overpressures. Laminated security glazing supplied in common architectural thicknesses and weights can substantially reduce injury caused by flying glass and even reduce the cost of repairing a bombed facility near a bomb attack by reducing the extent of damage and the amount of debris to be cleared. Even the thinnest laminated glass offered better forced-entry protection than monolithic glass of the same thickness. Various thicknesses of laminated glass offer resistance to ballistic penetration. Laminated glass costs 15 to 20 percent more than tempered glass of the same thickness, but it is cost effective when the possible costs of security breaches are taken into account.