Fire Protection: Closures and Glazing

Fire protection closures. Fire protection closures are units comprising:
- a door, or doors, with associated frames and fixings for the frame
- a self-closing device (either a flat spring or door closer with hydraulic damping)
- a closing sequence regulator (on double doors)
- relevant mechanisms required if sliding, roller or vertical lift doors are fitted
- a door lock
- a locking system with release devices for closures, which, during normal usage, must be held open and closed only in the event of fire.

If a fire takes hold, considerable distortion can occur between the wall and the door. Fire protection doors should therefore be considered in conjunction with the method of construction of the wall (i.e. solid walls or stud construction) to ensure that the combination is effective and permissible.

The level of fire resistance is dependent to a large degree on:
- the size of the door and opening
- the precision of manufacture
- the standard of workmanship during installation.

Smoke protection doors. Smoke protection doors are suitable for the limitation of smoke propagation in buildings but they are not fire protection enclosures in accordance with fire regulations. These doors are self-closing doors that are intended, when closed, to stop smoke passing from one part of the building into another.

Closures in walls of lift shafts. Closures in lift shaft walls, particularly the doors, must be constructed to prevent fire and smoke being transmitted to other floor levels. The effectiveness of the closure is then only assured, if suitable lift shaft ventilation is available and the lift cage consists predominantly of fire resistant construction materials. The size of the ventilation openings will be given in the local building regulations. In general, a cross-section of at least 2.5% of the plan area of the lift shaft is required, but this must be at least 0.1 m².

Fire protection glazing. Fire protection glazing is a component consisting of a frame with one or more light transparent elements (e.g. panes of fire protective glazing), mountings, seals and means of fixing. It will resist fire, in accordance with the classification, for 30, 60, 90, or even 120 minutes.

Heat radiation resisting glazing. These are light transparent components that can be arranged vertically, horizontally or be inclined. They are suitable as fire protection glazing to impede the propagation of fire and smoke and the passage of heat radiation, according to their fire resistance period. Their stability will have been demonstrated in a strength test.

Heat radiation resistant glazing loses its transparency in the event of fire and provides wall-like fire protection. This implies that thermal insulation must be preserved during the whole of the fire resistance period.

This type of glazing is predominantly used internally, although recent developments have rendered it suitable for external use.

Heat radiation resistant glass consists of two prestressed panes 6mm apart which are prefabricated as a type of double glazing unit. During manufacture, the air between the panes is replaced by an organic, water- containing substance (gel). In the event of fire, the individual pane exposed to the fire cracks and the gel then compensates for the heating by evaporation. Due to the scalding on the surface of the fire protective layer, the glass becomes discoloured and is then non-transparent to light.