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Fire Ground Hydraulics

Fire Ground Hydraulics. Fire Ground Hydraulics?. 175?. Pump Pressure?. 120?. P.S.I.?. Loss per 100 ft.?. Hose Diameter?. Elevation Loss?. Device Loss?. GPM?. 200?. 150?. Nozzle pressure?. Fire Ground Hydraulics. Single, Selectable Gallonage, & Automatic.

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Fire Ground Hydraulics

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  1. Fire Ground Hydraulics

  2. Fire Ground Hydraulics? 175? Pump Pressure? 120? P.S.I.? Loss per 100 ft.? Hose Diameter? Elevation Loss? Device Loss? GPM? 200? 150? Nozzle pressure?

  3. Fire Ground Hydraulics Single, Selectable Gallonage, & Automatic Pump Discharge Pressure equals Nozzle Pressure + (Total Pressure Loss) PDP = NP+(FL+DL+EL) NP = Nozzle Pressure FL = Friction Loss DL = Device Loss EL = Elevation Loss

  4. Friction Loss Hoseline Friction Loss FL = CQ2L FL = Hoseline friction loss in PSI C = Friction loss coefficient* Q = Flow rate in hundreds of GPM (GPM/100) L = Hose length in hundreds of feet (Feet/100) * Refer to NFPA Fire Protection Handbook

  5. Hose Friction Loss(per 100 feet of hose)

  6. Elevation Pressure LossDevice Loss Elevation Pressure EP = 0.5H 0.5 = A constant H = Height in feet Device Loss Appliance Friction loss in PSI

  7. Calculating for Pump Discharge PressureSelectable or Single Gallonage or Automatic 125 gpm at 100 psi NP on 150 ft. of 1¾” hose PDP = NP+TPL TPL = FL = CQ2L TPL = (15.5)(1.25)2(1.5) TPL = 36 PDP = 100+36 PDP = 136

  8. Calculating for Pump Discharge PressureSelectable (Change Flow Setting) or Automatic 150 gpm at 100 psi NP on 150 ft. of 1¾” hose PDP = NP+TPL TPL = FL = CQ2L TPL = (15.5)(1.5)2(1.5) TPL = 52 PDP = 100+52 PDP = 152

  9. Calculating for Pump Discharge PressureMaster Stream 1½” Smooth Bore Tip 598 gpm @ 80 psi NP on 300 ft. of 3” hose PDP = NP+TPL TPL = FL+DL TPL= CQ2L+Device Loss FL = (.677)(5.98)2(3) = 73 DL = 25 TPL = 73+25 = 98 PDP = 80+98 PDP = 178

  10. Hoseline Friction Loss • Coefficients from NFPA Fire Protection Handbook • Manufacture, construction, age & condition of hose are determining factors • Actual coefficients of friction can be determined • Test your hose for actual coefficients • Refer to IFSTA Fire Streams Manual for procedures

  11. Single & Selectable Nozzles • Pump pressure charts can be made for any hose lay • Hydraulic calculations can be pre-planned • Communication is key to safe operations • When operated at correct pressures, they will deliver the stated flow • For multiple lines of different size, flow &/or length, pump to the maximum required pressure & gate the other discharge valves to correct pressure for each line

  12. Automatic Nozzles • Hydraulic calculations are simpler • Nozzle pressure remains constant (typically 100psi) • If calculations are incorrect, automatic nozzles will deliver the available flow • Maximum reach with available water • As nozzles are throttled, pump operator should avoid “chasing” the pressure gauge • The goal should be to maintain the minimum pressure necessary for the line

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