Relay Pumping Operations


A. Each fire department, or group of fire departments in particular region, should have SOP for type of relay pumping operation they will use

B. Agencies that have potential to work together on relay pumping operations should perform relays in training environment on regular basis

C. Some organizations have organized procedures for providing relay pumping capabilities at emergency scene

  1. When IC determines necessary to use relay to provide adequate amount of water to scene, relay

       task force or strike team requested

  2. Three to five pumpers dispatched to scene

  3. Companies come in and establish water supply independent of companies already operating on


D. Two basic designs for relay pumping operations: the maximum distance relay method and constant pressure relay method

E. Maximum Distance Relay Method

  1. Involves flowing predetermined volume of water for maximum distance pumped through particular

      hose lay

  2. By using table in Appendix A, operator can determine distance that certain flow pumped through

      hose carried on apparatus

  3. Built into figures in table is 20 psi residual pressure at next pumper in relay

  4. Figures in chart based on discharge pressure of 200 psi for 2½- and 3-inch hose and 185 psi for

      4- and 5-inch hose

  5. When considering distances in table in Appendix A, operator must keep in mind--all fire

      department pumpers rated to flow maximum volume at 150 psi, 70 percent of maximum volume at

      200 psi, and 50 percent of maximum volume at 250 psi

  6. Because table in Appendix A based on discharge pressures of 185 and 200 psi, following are

      minimum pump capacities used to achieve flows/distances on tables:

      a. 250 and 500 gpm flows: 750 gpm rated pumper

      b. 750 gpm flow: 1,250 gpm rated pumper

      c. 1,000 gpm flow: 1,500 gpm rated pumper

      d. 1,250 gpm: 1,750 gpm rated pumper

  7. If local procedure use distances less than those on chart, possible to use smaller capacity pumps

      than listed or remove one or more pumpers from relay

  8. Using figures in table in Appendix A, number of pumpers needed to relay given amount of water

      determined by using following formula:

Relay Distance + 1 = Total Number of Pumpers Needed

  Distance From


Appendix A

Note that when using formula, always need to round up to nearest whole number. For example, if answer 3.2, actually need four pumpers to achieve flow.



If single line of 3-inch hose used, how many pumpers needed to supply 1,000 gpm to fire scene 1,000 feet from water source? From table in Appendix A, can be seen that maximum distance water will flow at 1,000 gpm through 3-inch hose 225 feet. Divide figure into distance to fire, add 1 for attack pumper:

1,000 = 4.4 +1 = 5.4 or 6 pumpers needed




If two lines of 3-inch hose used, how many pumpers needed to supply 750 gpm to fire scene 2,000 feet from water source?

Find distance in table in Appendix A for two 3-inch inch hoses at 750 gpm

Then divide distance into total distance

2,000 = 1.25 + 1

1,600 = 2.25 or 3 pumpers needed

  9. When using method to establish relay, common sense used

  10. By checking tables, 750 gpm flowed for 1,600 feet through dual 3-inch hoses

  11. If distance to fire scene 2,000 feet away, place 1,600 feet between source pumper and relay

        pumper, with only 400 feet remaining between relay pumper and attack pumper

  12. Place relay pumper more toward middle of supply hose

  13. If engine companies with different sizes of supply hose on board, distances between pumpers

        varied accordingly

  14. For example, if several engine companies setting up 1,000 gpm relay using 5-inch hose, each

        pumper 2,050 feet apart

  15. If engine shows up with dual lay of 3-inch hose, it can participate as long as dual 3-inch lay limited

        to 900 feet

F. Constant Pressure Relay Method

  1. Second type of relay pumping operation is constant pressure relay

  2. Relay method establishes maximum flow available from particular relay setup by using constant