Some parts of a fire sprinkler system include sprinkler heads, alarm valve, motorized alarm and stop valve. The sprinkler system is initiated when the fusible links or glass bulbs inside the sprinkler heads melt due to higher temperatures. Some systems come equipped with recessed sprinkler heads hidden behind a cover plate. The plate falls away when exposed to high heat.
The sprinkler heads cause the alarm valve to open which allows water to enter the sprinkler system. The force of the water rushing through the system operates a motorized alarm bell. The bell alerts the building's occupants that a fire is detected and that the sprinkler system has been turned on.
A sprinkler system's stop valve is used to shut off the flow of water completely. If the stop valve is closed, water cannot reach the alarm valve. The stop valve is mainly used to cease the flow of water to a sprinkler system while it is being repaired.
A common misconception is that all of the sprinkler heads open once the sprinkler system is triggered. Rather, only the sprinkler heads that detect high temperatures allow water to escape the system. This limits the potential damage caused by all of the heads opening at once and flooding the building.