Pumping Apparatus Driver Operator (1st Edition)
Chapter 11 - Operating Fire Pumps
"By the Numbers"
NOTICE: Equations and examples from this chapter are not covered on this study page. It is suggested that pictures and examples be thoroughly studied for this chapter. Copyrights prohibit them to be displayed here.
Pages 273-294 (Troubleshooting Pumping Operations) are also not covered.

  • Apparatus may override the parking brake system at engine speeds as low as 1,300 rpm.
  • On a manual or automatic transmission, when the PTO or pump is engaged, the speedometer should show a speed slightly above 0 mph.
  • If discharge pressure is increased too much, the residual pressure may drop below 0 psi and collapse the supply line, interrupting the water supply.
  • Incoming pressure from a hydrant or supply pumper should be kept at 20 psi or above.
  • Color coding of hydrants is discussed in NFPA 291, Recommended Practice for Flow Testing and Marking of Hydrants.
  • 4-way hydrant valves have a 2nd discharge outlet that is 4 1/2" or 5" and allows for a 2nd pumper to connect to the hydrant without interrupting the flow of water.
  • When using 2 1/2" or 3" lines to supply a pumper directly off hydrant pressure, it is recommended that the lines be no longer than 300 feet.
  • If the master intake gauge drops below 20 psi, the throttle should not be increased due to danger of cavitation.
  • The maximum amount of vacuum that most pumps develop is about 22 inches of mercury.
  • For pumpers to approach their rated capacity using a traditional strainer, a minimum of 24 inches of water should be present in all other directions from the strainer.
  • If there is not 24 inches of water above a strainer, there is a possibility of a whirlpool forming around the strainer, causing air to be drawn in.
  • Low-level strainers allow water to be drafted down to a depth of about 2 inches(DISCREPANCY pg. 304 states about 1" to 2").
  • 1 foot of lift is equal to 0.885 inches of mercury.
  • Maximum theoretical lift is 33.9 feet (DISCREPANCY page 297 states 33.8).
  • Water that is above 90oF or below 35oF may adversely affect a pumps ability to reach capacity.
  • Water several feet below the surface of a static source may be 5oF to 10oF warmer than the surface water.
  • Fire department pumpers are usually rated at 10 feet of lift.
  • All available atmospheric pressure is required for a pumper in good condition to lift water 23 or 24 feet.
  • Maximum lift considered reasonable for most pumpers is 20 feet.
  • At 20 feet of lift, the amount of water that can be supplied is only about 60% of the rated capacity of the pump.
  • Most priming pumps are intended to work best when the engine is set from 1,000 to 1,200 rpm (this rpm is not required by electric-driven priming pumps).
  • The reading on the master intake gauge when drafting should read about 1 inch for every 1 foot of lift (measured from surface of water to level of intake orifice).
  • Priming action generally takes 10 to 15 seconds and should not take more than 30 seconds (45 seconds for pumps larger than 1,250 gpm).
  • If the pump cannot be primed within 30 seconds, stop and check for problems.
  • After priming and before opening discharge when priming, the throttle should be set to boost pressure between 50 to 100 psi. As the discharge is opened, if pressure drops below 50 psi, wait for the pressure to stabilize before opening the discharge further.
  • Fire department connections consist of a siamese with at least two 2 1/2" female connections or 1 large diameter sexless connection, connected to a clappered intlet.
  • With any indication of a fire in a building with a fire department connection (FDC), a minimum of two 2 1/2" or one 3" line should be connected to the FDC.
  • Generally, one 1,000 gpm pumper should supply the FDC for every 50 sprinklers that are estimated to be flowing.
  • A general rule of thumb for supplying an FDC is 150 psi, unless otherwise stated.
  • Standpipe systems have 2 1/2" or 1 1/2" connections on each floor serviced.
  • About 5 psi + FL should be added to the desired nozzle pressure for each floor above the standpipe connection that will have operating fire streams.
  • Maximum pump discharge pressures for standpipe systems is 200 psi unless otherwise stated.