How Fire Sprinklers Work

Fire sprinkler systems ward off the risks of fire consuming your property, but most homeowners have no idea how fire sprinklers work. Sprinkler systems offer several advantages over fire extinguishers. First, fire sprinklers can activate even when you aren't home. Second, you don’t have to do anything to activate the system; the detectors will automatically start the sprinklers for you. Third, the sprinklers suppress fire before it creates more smoke and causes more extensive damage.

How Fire Sprinklers Work

A sprinkler system starts with a network of water pipes that are located in the ceiling of your house. The pipes are drilled with holes that allow the water to escape. These holes connect to the individual sprinklers that protrude from your ceiling. Basically every sprinkler operates the same way as your ordinary faucet. You usually turn on your faucet’s screw to open up a valve that will allow water to flow. A fire sprinkler, on the other hand, has a heat-sensitive plug that will open once the system detects a fire.

Heat-Sensitive Plugs

Heat-sensitive plugs come in two forms: an alloy of bismuth, lead, tin and cadmium (more commonly known as Wood’s metal), or a glass plug made with glycerin. The whole point of having heat-sensitive plugs is that they break when the system detects an increase in heat. When the plugs break, they allow water to rush in and the sprinklers to go off.

Glycerin Plugs

The glycerin plug uses the principle of thermal expansion. If the temperature increases, the bulb expands until it breaks, allowing the water to flow through.

Wood’s Metal Plugs

The Wood’s metal plug works in quite a different way. A sprinkler with this kind of plug will have two metal arms that the plug keeps together. For an inactivated sprinkler, the Wood’s metal plug remains intact and the arms stay together tightly so that no water escapes from the sprinkler. You will notice a metal deflector in the shape of a flow right beneath the sprinkler.

In case of a fire, the hot gases will move up to the ceiling. Once the temperature of the room exceeds 70 degrees, the Wood’s metal plug will start to melt. Once the metal plug has completely melted, the arms will be free to break open. When that happens, water will be able to flow out from the pipes. The reason why the water flows in a sprinkling motion is that the water from the pipe hits the deflector. Only the sprinkler near the source of the fire will activate. If the fire spreads throughout the other areas of the house, the nearby fire sprinklers will go off as well. The water released by the fire sprinklers will extinguish any small fire or will contain a huge one until the fire department reaches your house.