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Published byJocelyn Lytton Modified about 1 year ago

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Fire Ground Hydraulics

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

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

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Friction Loss Hoseline Friction Loss FL = CQ 2 L 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 Hoseline Friction Loss FL = CQ 2 L 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

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Hose Friction Loss (per 100 feet of hose)

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

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

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

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Calculating for Pump Discharge Pressure Master Stream 1½” Smooth Bore Tip PDP = NP+TPL TPL = FL+DL TPL = CQ 2 L+Device Loss FL = (.677)(5.98) 2 (3) = 73 DL = 25 TPL = = 98 PDP = PDP = 178 PDP = NP+TPL TPL = FL+DL TPL = CQ 2 L+Device Loss FL = (.677)(5.98) 2 (3) = 73 DL = 25 TPL = = 98 PDP = PDP = psi NP on 300 ft. of 3” hose

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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 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

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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 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

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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 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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