Fire Pump Theory Flashcards
Two types of fire pumps
- Positive displacement
- Centrifugal
When are positive displacement pumps used with centrifugal pumps?
-As priming pumps
True or false: positive displacement pumps pump a definite amount with each evolution?
-True
Three main factors that influence discharge pressure of centrifugal pumps:
- Amount of water being discharged
- The greater the speed of the impeller the greater the pressure developed
- Pressure of water when it enters the pump
Single Stage Pump
- number of impellers
- capacity (gpm)
- psi
- “____ suction” impeller
- one impeller
- 2000gpm capacity
- “double suction” impeller (takes water in from both sides)
- 150 psi
Two Stage Pump
-Volume (parallel) mode
- Each impeller flows 50% of the capacity
- Max flow
Series (pressure) mode
- Water in one impeller and then to the next thus boosting pressure
- Higher pressure, lower flow
Two Stage Pump
-Transfer valve psi
75psi
Pump capacity at:
150psi
200psi
250psi
150psi: 100%
200psi: 70%
250psi: 50%
Engine speedometer reading for midship transfer drive pumps when engaged
10-15mph
Intake Piping
-NFPA 1901:
Pumpers w/ a capacity > 500 gallons should be able to flow ____ GPM from the tank
Pumpers with a capacity < 500 gallons should be able to flow ____ GPM from the tank
> 500 gallons: 500gpm
< 500 gallons: 250gpm
Max GPM on 2 1/2” inlet
250gpm
How many 2 1/2” discharges per 250gpm pump capacity at a minimum?
One
Piping diameter for 1 3/4” handlines
2” piping
NFPA 1901
-Slow acting control valve for all valves ____ inches or larger
3”
