Relay Pumping Operations

  7. At setting, valve not open and cause excessive fluctuations when minor changes in flow occur

  8. If attack pumper equipped with readily adjustable intake relief valve, set between 50 and 75 psi to

      establish stable operating condition for attack pumper

  9. If attack line shut down or amount of discharge changes, friction loss in supply line decreases and

      residual pressure increases

  10. Intake relief valve opens, allowing water to dump out of intake

  11. Flow through supply line and entire relay increases and pressures return to original settings

  12. Additional flow requirements by attack pumper reduces residual pressure and causes relief valve

        to close

  13. Dumping action stops, allowing pressure to again return to original setting

  14. Small variations in pressure not significant and no attempt made to maintain exact pressures

  15. As long as the intake pressure does not drop below 10 psi or increase above 100 psi, no action

       required

  16. Changing pressure at any pumper in relay operation has effect on others

  17. Excessive changes result in constantly varying pressure throughout relay

  18. Takes long period of time for pressure change to actually occur in long relay

  19. Time delay often responsible for overcorrection errors that have negative effects for entire relay

       operation

  20. Effective relay operations require good communications

  21. Each unit in relay aware of actions of other units so operations coordinated properly

  22. When pumpers within sight of each other, hand signals used; in extreme cases, messengers on

        foot effective

  23. Where additional radio frequencies available, one channel dedicated to coordination of water

        supply operation

  24. Once water moving, minimum of communication required

  25. When units involved in relay equipped with incompatible radios, portable radios useful

  26. Radio equipped ambulances or utility units used to establish communications throughout relay

E. Shutting Down the Relay

  1. Relay operations shut down from fire scene first

  2. If source pumper shut down while rest of relay still operating, pumpers run out of water and

      cavitation can result

  3. Starting with attack pumper, each operator slowly decreases throttle, opens dump line, and takes

      pump out of gear

  4. Once all pumpers shut down, hose drained and readied for reloading

 

REVIEW:

Relay Pumping Operations

   • Relay Apparatus and Equipment

   • Relay Pumping Operational Considerations

   • Types of Relay Pumping Operations

   • General Guidelines for Relay Operations

 

REMOTIVATION: Being able to effectively and efficiently relay water at the scene of a fire may make the difference between a good save and another foundation.