To keep fire hydrants operative in cold climates, the main pipe is buried below the frost line (the deepest point the ground freezes). The hydrants used are considered dry barrel, which means when they are closed, the water is held in the main pipe below the frost line. In extreme cold climates, hydrants are outfitted with thaw wires or thaw pipes that allow steam or electrical current to be added to prevent lines from freezing. Fact contributor: Stewart Osgood, PE #EngineeringFacts #WaterResources #CivilEngineering
Project Manager at DOWL
1yBonus fact - The dry barrel has a "drain ring" at the base so water can drain out after the hydrant has been used.