How sprinklers operate

Sprinklers are simple devices that are individually operated directly by the heat from a fire

When a fire starts a plume of hot gases rise to the ceiling. If a sprinkler is present, a glass bulb or solder link gets hot and at a specific temperature (typically 68°C) breaks releasing a cap and allowing water to flow onto a specially designed diffuser
 
The diffuser breaks up the water flow into carefully controlled droplets which penetrate the fire plume and cool the burning material below its ignition point, thus putting out the fire

Only the sprinkler/s directly over the fire are operated

The sprinklers are connected to pipework, usually filled with water which is supplied either from the water mains or from a storage tank via a pump

When a sprinkler operates the flow of water in the pipework operates a flow switch which in turn operates an alarm system
 
The flow of water is small, usually less than 1/100th the water used by the Fire and Rescue Service
 
Sprinklers do not go off accidentally and are only triggered by real fires

Sprinklers are very reliable and only *1:16,000,000 exhibit any form of manufacturing defect