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Glass Fire Resistance

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Fire resistance in glazed partitions can take the form of being

Integrity Only (E)

Integrity and Radiation reducing (EW)

Integrity and Full Insulation(EI)

The letters E, EW, and EI are the proposed new European codes for the glass types.

 

Table F1 gives an indication of the radiated heat level against time which may be expected from the various glass types.

 

glass-fire-resistance

Radiation controlled glasses are those which reduce the measured level of radiated heat to less than 15kW/m²at 1 metre distance.  Using normal panel sizes, this is the radiation level at which it is considered to be impossible for the spontaneous ignition of building materials, or for a heat zone to be generated barring the safe passage of people.


The radiation reducing glasses are nominally 7-11mm single layer laminates or gel filled. The full insulating glasses are multi-laminates or gel filled.12-55mm in thickness. The use of radiation reducing glasses will undoubtedly increase as more European standards bodies set standards for radiation control without the requirement for full Insulation.

The selection of the type of glass is primarily controlled by the fire safety officer, for the project with reference to Building Regulations. These will cover escape routes, distances, active safety systems within the building etc.

The prime usage of insulating or radiation reducing glasses is around stairwells and escape route meeting points, where radiated heat will be a major factor in safe escape. The industry is aware that some of the regulations regarding FR screens can be improved upon by using Fire Engineered solutions, specific to the building, which may result in lower insurance premiums. The Loss Prevention Council in their Code of Practice make mention of this approach in their guide for the fire protection of buildings.

 

The design of fire rated systems has to be undertaken with great care, and the installation instructions followed to the letter, to ensure that the result complies with the fire certification. Glazed partition systems are usually rated up to a maximum of 60 minutes, either integrity only, or integrity and insulation. The rating is generally indicated as below

30/0 30 minutes integrity only
30/30 30 minutes integrity and 30 minute insulation
60/0 60 minute integrity only
60/30 60 minutes integrity and 30 minute insulation
60/60 60 minutes integrity and 60 minute insulation


Radiation reducing glasses have at this time, no BS test rating or Building Regulation coding, but are normally referenced in the same manner, eg 30/15 which is 30 minute integrity and 15 minutes radiation reduction to less than 15KW/m at 1 metre distance.
Framework for glazed systems can be in aluminium, steel or timber for up to 30 minutes, but only steel or timber for greater than 30 minutes.  As mentioned earlier the design of framework for glass partitions is critical, to ensure that there is sufficient expansion allowance, whilst maintaining a secure glass retention within the frame.
This is especially true for soda-lime glasses, which are edge cover sensitive due to their relatively large expansion rates. Soda-lime glasses should never be used in timber systems above 30 minutes, because of the shading effect of the timber cover causing a thermal gradient within the glass. Guidance should be sought from Avanti for all fire rated glazing applications, and the installation must only be carried out by accredited glaziers.