Engine Company, Structural Firefighting

Developing Accurate Pump Discharge Pressures

Issue 7 and Volume 171.

By PAUL SHAPIRO Fireground hydraulics has been and still is the method taught to pump operators for developing pump discharge pressure (PDP). It involves mathematical formulas as well as multiple concepts to measure water flow (gallons per minute), friction loss, exit or nozzle pressure (it’s called both), weight of water measured in pressure gain or loss, and so on. Everything taught in these classes is accurate as far as physics is concerned. However, some issues, such as friction loss in fire hose, can affect the accuracy of fireground hydraulics. There are many brands of fire hose, which vary in quality, and quality affects friction loss in hose. Let’s put the accuracy aside. The formulas used for fireground hydraulics can be complicated, and some pump operators may find it difficult to do mathematical equations quickly under the stress of an emergency. To avoid having to calculate mathematical equations on the fireground,…

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