DRAFTING HYDRANTS FOR HIGH-CAPACITY WATER SUPPLY

DRAFTING HYDRANTS FOR HIGH-CAPACITY WATER SUPPLY

Areas not served by public water systems can be equipped with drafting hydrants to provide a reliable water supply. If the incident is close enough to the water source, a pumper can be used to bring water directly to the scene by means of a hoseline or a relay. When farther distances are involved, a pumper can draft from a hydrant to fill tankers that will shuttle water to the scene. In either case, the hydrant should be capable of supplying enough water for the pumper to operate at its maximum rated capacity-

The maximum flow rate of a dry' hydrant can be affected by staticlosses resulting from natural causes or by the piping used with the drafting hydrant. Static losses—such as the lift from the water to the fire pump, atmospheric pressure, and the temperature of the water—result from natural causes; they remain the same regardless of the hydrant’s flow rate. A dynamic type of pressure loss occurs as the water moves through the drafting hydrant and associated piping; the loss is proportional to the velocity of the water as it travels through the waterway.