Domestic fire sprinklers consist of a simple control valve, pipe work and sprinkler heads, either connected to a dedicated alarm or incorporating hard-wired smoke detectors.

In normal, non-fire, conditions, the sprinkler is totally inactive, basically it just waits for a fire to occur. The system is charged with water from the mains which is stopped from flowing by a plug and generally a glass bulb. The bulb contains a liquid which when the desired temperature is reached, expands and breaks the glass, allowing water to flow.

When a fire starts, heat rises to the ceiling and at around the 60 degree centigrade mark, the cover plate drops off.

After the cover plate drops, the sprinkler is ready for action.

The deflector plate drops at the same time.

It is the deflector plate which governs the water pattern of the sprinkler.

When the temperature at the ceiling reaches 68 degrees centigrade, the glass bulb shatters, allowing the plug to fall away.

Once the plug has fallen away, water is released which hits the deflector plate and starts fighting the fire.

If a flow switch has been fitted, after 5 seconds an internal AND external alarm will sound to alert not just occupants of the house, but also neighbours that a fire has broken out. The external box fitted by Spencer-Fire carries the legend “FIRE ALARM DIAL 999”, this means that even if your property is empty, someone will call the fire service.