"Bullet proof" is the more commonly used term for materials classified as "bullet resistant." These materials are generally used in situations where there is a threat of armed attack on people or buildings. Banks, police stations and courthouses are among the places using these materials in different forms, particularly glass and doors. Individuals wear bullet resistant vests for protection.
Bullet resistant glass is used when protection from guns is needed, but the person behind the glass also needs to see people, such as in a bank. It is also used in the external windows of some buildings and in cars. There are four types of bullet resistant glass. Laminated glass consists of layers of glass coated with polyvinyl butyral (PVB), and is the cheapest form. Acrylic glass is only suitable for indoor use and only offers protection against the lowest ballistic ratings. Polycarbonate glass is another indoor-only glass, but offers more protection against physical attack because it doesnÂ´t shatter like the laminated form. Finally, glass-clad polycarbonate is scratch-resistant, slightly tinted and protects against bullets and physical attack.
Bullet resistant panels usually surround the bullet resistant glass. The panels are made of steel or a fibreglass composite attached to a standard stud-wall construction. Steel panels are the least expensive, but they have to be made-to-measure before installation and they are heavy to work with. The fibreglass panels cost more, but are easier to work with because they are lighter and workmen can cut them to size on site. Once the panels are attached, they are painted and have the appearance of an ordinary wall.
Kevlar is the brand name of a bullet resistant fabric. It is made of a very strong fabric called aramid that is similar to nylon. This tough fabric is woven into a pattern resembling the structure of a spider's web, and this adds to its durability. Kevlar works by catching a bullet in its web of fibres that also adsorb and disperse the impact energy. On top of this, the material doesn't melt. Apart from its use in bullet-resistant vests, it is used in firefighting equipment and for storm shelters.
Bullet resistant materials do not offer universal protection against any type of firearm. Also, some materials offer protection from a single bullet, but not from a sustained attack. Each type of gun poses a different threat, with rifles being more powerful than handguns, for example. Commercial businesses use a ratings system to classify materials with the lowest ratings giving protection against less powerful handguns, such as the 9mm and .44 magnum. Higher ratings are needed to protect against rifle cartridges.
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