Transcript Guide to Automatic Nozzles

Fire Ground Hydraulics
Fire Ground Hydraulics?
P.S.I.?
Nozzle pressure?
200?
150?
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
Friction Loss
Hoseline Friction Loss
2
FL = CQ 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
Hose Friction Loss
(per 100 feet of hose)
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
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 = CQ2L
TPL = (15.5)(1.25)2(1.5)
TPL = 36
PDP = 100+36
PDP = 136
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 = CQ2L
TPL = (15.5)(1.5)2(1.5)
TPL = 52
PDP = 100+52
PDP = 152
Calculating for Pump Discharge Pressure
Master 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
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
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
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