What kind of mortise lock is suitable for installation on fire rated doors?

In order to provide an effective barrier to a fully developed fire, a door has to remain closed within the frame. In the case of single action doors, this role might be undertaken by a latch. In certain cases there is a need for a lock to be fitted to a fire-resisting door. This might be on a duct door which is normally kept locked with only occasional access to service equipment, or other fire-resisting doors which for security reasons are locked for periods of time.

Where security is in conflict with easy egress, a full risk assessment should be made. Doors which are normally unlocked when the building or area is occupied may be fitted with locks for out-of-hours security. A thumb-turn on the inside of the door will give means of escape to anyone inadvertently locked in. Where the door will be normally locked during occupation, e.g. a dispensary or a wages office, then hardware such as panic escape devices to BS EN 1125 or emergency exit devices to BS EN 179 should be used.