Security Glass And Bullet Resistant :

Safety against Burglary, Theft and Vandalism :In the prevention of burglary or vandalism, one of the ke
y factors is time. The more time it takes for the thief or vandal to overcome the obstacle, the more dissuasive and efficient it is. Basic laminated glass as a glass-PVB-glass sandwich is safe for minor intrusions but it can be further reinforced with additional layers of PVB and using multiple layered sandwich of ‘GLASS + PVB + GLASS + PVB + GLASS’ etc. to make for increased resistance to attack
. Laminated glass offers an almost endless number of possible combinations depending on the number of glass elements and inter-layers, their thickness and their colours. Security laminated glass against burglary is mainly used in large windows without grills and in shops for jewelry, cameras, electronic instruments etc.

Bullet Resistant Glass:

The increasing occurrence of armed attacks has led many companies to develop laminated glass specially formulated and tested to protect people against fire-arms. In addition to its anti-burglary function, it is designed to stop projectiles and limit or avoid splintering on the opposite side of the impact, while maintaining complete visibility and light transmission. According to the type of weapon and ammunition, and the degree of protection required, these laminated glasses vary in thickness and composition.

Thickness and Combination of the Bullet Resistant Glass will depend on factors like, resistance required against type of weapon, striking velocity, type of ammunition, mass of ammunition and range of fire etc. The different level of protection, the Bullet Resistant Glasses are manufactured for following ratings.

Bullet resistant glass is generally used for cashier counter in banks, post offices, embassies, ministries, police stations, nuclear centers, military installations, high security vehicles and cash carrying vans etc.

Fire Rated Glasses :

Glass used in fire escape passages and fire doors have to fire rated. The requirement for the suitable type depends on the area of the glazing and estimated time for safe evacuation of occupants of the building in case of fire. The Fire resistance of a glass construction element is measured against a number of criteria.

Stability & Intergrity in flames hot gases and smoke (E): The glass does not break & stays in sash for designed minimum time and prevents flames, smoke and hot gases (but not heat) from passing through. The fire remains contained.

Limiting radiation (W): The glass restricts the amount of heat passing through it to the side which is to be protected (radiation may not exceed 15kW/m2).

Thermal insulation (I): The average temperature of the glass on the protected side remains below 140°C which eliminates the risk of self-combustion either due to radiation or convection of exposed materials
and means that buildings can be evacuated safely & camly.
These are thus 3 types of fire resistants glasses namely ‘E’, ‘EW’ & ‘E1’ for a rating of 30, 60, 90 or 120 minutes.

Chemically Tempered Glass :
Glass can also be tempered by a chemical process but it is much more expensive and time consuming in production, as compared to the normal thermally tempered glass. It is therefore, not used in normal architectural applications.

It is generally used were thermal tempering is not possible like in thin glasses (below 3mm thickness) or for small glasses (like for watches) and certain applications were the optical quality requirements are very
high.

Chemical tempering can be used on previously curved glass, and also on the glass that is less than 3 mm thick. The shape of the glass sheet will not be modified during tempering, so perfect geometry can be achieved.

Other Speciality Glasses:

There are other speciallity glasses like anti-reflective, self cleaning, photochromic, electrochromic, low refraction, low expansion glasses and many other types, which are used occasionally and rarely in achitecturial applications and are not covered in this book.