Menu Close

How does fire glass work?

Modern fire resistant glass is vital in the protection of safe escape routes in modern buildings. The provision of a safe escape cell, especially in high rise building, is a vital consideration for modern planners and architects. Modern designs favour light and open spaces which leads to building designs incorporate large areas of glass.

Modern glass is able to perform a wide range of functions in building designs, keeping them warm, shading rooms from solar gain, and protection from fire, impacts or blasts. New applications are developed as the science of glass manufacture improves.

How is fire resistant glass made?

Modern fire glass is can be supplied clear without internal wire. This is achieved by the use of multi-layered glass which create a sandwich of transparent intumescent layers that are designed to react to heat. The number of layers and the thickness of the glass will be determined by the fire resistance level that needs to be achieved. 30 minute integrity (E30) glass can range from 6mm to 12mm in thickness whilst 60 minute integrity and insulation will typical starts at 25mm. The fire glass can be incorporated into double glazed units (DGU) which will improve their noise and heat insulation capabilities. Due to the requirement to incorporate a steel spacer bar these fire rated double glazed units will not out perform a standard double glazed unit fitted with a thermal spacer bar.

What happens during a fire?

As a fire develops heat will build up inside the room. The fire will begin to consume the flammable materials and using oxygen as a fuel to intensify its effects. The temperature inside the room can quickly escalate to levels in excess of 600 Celsius. As the level of heat begins to rise the intumescent layers in the glass will begin to react to the heat. The closest layer to the heat source will begin to expand in reaction to the heat source, changing into a opaque colour and absorbing the energy transmitted by the fire. This reaction will begin at around 120 Celsius. This forms a tough protective insulating shield that is designed to slow the progress of the fire.

The effects of the fire will cause the glass to begin to fail and cracks will begin to appear in the first glass layer. The intumescent layer will have the secondary function of helping the glass layer to remain in place without failing.

As the fire continues the layers of glass and intumescent materials will react to the fire in a similar manner in a cascade effect in order to keep the other side of the glass unit safe from the effect of the fire to allow escape of the occupants of the building.

Fire insulatig glass unit, example of double glazed fire glass.

Leave a Reply

Your email address will not be published. Required fields are marked *