Relay Pumping Operations

TOPIC: RELAY PUMPING OPERATIONS TIME REQUIRED: ONE HOUR MATERIALS: APPROPRIATE AUDIO VISUAL SUPPORT REFERENCES: PUMPING APPARATUS DRIVER/OPERATOR HANDBOOK, FIRST EDITION, IFSTA PREPARATION: MOTIVATION: OBJECTIVE (SPO): 1-1


      pressure in system

  3. Constant pressure relay depends on consistent flow being provided on fireground

  4. Attack pumper can maintain flow by using open discharge or secured waste line to handle excess

      beyond flow being used in attack lines

  5. Relay using constant pressure has several advantages if operators properly trained in use

      a. Speeds relay activation

      b. Each operator knows exactly how much hose to lay out and how to pump it without awaiting

         orders

      c. Requires no complicated calculations

      d. Radio traffic and confusion between pump operators reduced

      e. Attack pumper operator able to govern fire lines with greater ease

      f. Operators only have to guide and adjust pressure to one constant figure

  6. Forming the Constant Pressure Relay

      a. Position attack pumper at fire

      b. IC makes size-up and determines quantity of water needed

      c. Initial attack made with water carried on pumper

      d. Position largest capacity pumper available at water source if possible

      e. Crew begins making necessary connections to water supply

      f. Lay out hose load from relay pumpers according to procedures used jurisdiction

      g. Always leave at least two sections of hose in reserve in hose bed in event hose failure occurs

        during operation

      h. Connect all supply lines to pumpers in relay

      i. Operator for each pumper, except source pumper open unused discharge gate if pump does not

         have relay relief valve which allows air from hoselines to escape

      j. Pump 175 psi from pumper at water source

      k. Operator at first relay pumper closes unused discharge gate once steady stream of water flows,

          then advance throttle until 175 psi developed

      l. Each successive operator follows same procedure

      m. Each operator sets pressure regulating device

      n. Attack pumper operator adjusts discharge pressure(s) to supply attack line (s)

     o. Maintain flow from attack pumper during temporary shutdowns by using one or more discharge

         gates as waste or dump lines

      p. Do not shut down attack lines unless absolutely necessary

      q. If hoseline bursts, open discharge gate on relay pumper before rupture to dump water until

          length replaced

       r. Lay additional hoselines between apparatus in relay if additional water needed on fireground

  7. Operators in constant pressure relay keep correcting pump discharge pressure to 175 psi until:

      a. Intake pressure from pressurized sources drops to 20 psi

      b. If intake pressure drops below 20 psi, danger that pump will go into cavitation

      c. Operating hand throttle does not result in increase in rpm

  8. Constant pressure of 175 psi modified as needed for:

      a. Variations in relay pumper spacing

      b. Severe elevation differences between source and fire

      c. Increases in needed fire flow

      d. LDH requires lower discharge pressure to supply same volume of water

  9. When increasing relay pressure, source pumper adjusted until desired pressure reached

  10. Each successive pumper similarly adjusted

  11. When decrease in flow required, attack pumper throttles down

  12. One way is by opening dump line to relieve excessive water

  13. Source pumper should discharge dump line back into water supply source

  14. Relay pumpers toward water source successively throttle down to desired pressure

  15. Water supply officer or IC must realize flow and pressure limitations of given relay setup and

        should not attempt to exceed capabilities of apparatus and hose

 

IV. GENERAL GUIDELINES FOR RELAY OPERATIONS (EO 1-4)

A. Basic guidelines for all relay pumping operations, regardless of type chosen

B. Operators familiar with guidelines to be successful in relay pumping operation