3 of the Most Important Parts of a Fire Hydrant

In case of a fire, hydrants provide access to the system of water supply for purposes of extinguishing the flames. If you have ever wondered how a fire hydrant works, it may help to understand the different parts, some of which are hidden beneath the ground.

1. Valve

Most fire hydrants in the United States are dry barrel, meaning that they are connected to a water main, but a valve holds the water back until it is needed. That way, the water doesn’t sit in the hydrant at all times where it could freeze when the weather turns colder. When the valve is closed, it also opens an underground drain hole that allows any water remaining in the barrel to flow out. When the valve is open, the drain holes are plugged up and water flows up into the barrel. Because the valves need to be opened when needed, a valve turner is used to maintain the component and keep it in operational condition.

2. Stem Nut

Shaped like a pentagon, the stem nut is located at the top of the hydrant. It is what allows the valve to be opened from above the ground. Firefighters have a special tool to turn the stem nut and open the valve. The unusual shape of the stem nut prevents unauthorized access to the water.

3. Outlets

The outlets are the openings in the hydrant that allow the water to come out. Each hydrant has several different-sized outlets. Firefighters must open the outlets and attach the hoses before they can turn the stem nut to open the valve and turn on the water.

Once the fire is out and the hydrant is no longer needed, the firefighters must turn the stem nut to close the valve and turn off the water. Then they must detach the hoses from the outlets and replace their covers. The covers have chains to attach them to the hydrant so that they do not get lost as the fire is extinguished.