What unit of measurement is used for pump discharge pressure on most engine dashboards?

• A. Pounds per square inch (psi)
• B. Kilopascals (kPa)
• C. Bars
• D. Pounds per square foot (psf)

Answer: (A)

Discharge pressure is the pressure at the pump outlet that the operator must maintain to push water through lines and nozzles. On most fire engine dashboards, this value is displayed in pounds per square inch (psi) because psi is the standard unit for pressure in U.S. firefighting equipment. Using psi keeps discharge pressure readings consistent with nozzle pressures and friction-loss calculations, making it quick to read and apply in the field. Kilopascals or bars are metric units more common outside the U.S., and pounds per square foot isn’t used for pump discharge pressure in typical fire service practice. If you ever need a rough conversion, 1 psi is about 6.895 kPa or 0.0689 bar.