Pumps Flashcards
What is the definition of a pump?
A pump is a machine driven by some external power, used for imparting energy to fluids.
Pumps fall into what three categories?
Positive displacement
Ejector or jet
Centrifugal
WMFS appliances are mounted with “Godiva” two stage main fire pumps each comprising of what?
1st stage “centrifugal” pump (main jet)
2nd stage “peripheral” pump (hose reel)
What are the two main parts of a centrifugal pump?
Impeller
Casing
What are the characteristics of centrifugal pumps? (4 answers)
At any given speed where there is no flow, (no delivery open) the pressure is at a maximum.
Pressure decreases with an increase in discharge (opening of a delivery).
Pressure and flow increase as the pump speed is increased and vice versa.
When suction lift is increased pressure and flow decrease.
What are the advantages of a centrifugal pump? (4 answers)
Simple maintenance.
Can be run against closed deliveries without damage or danger.
They are small, light and compact relative to their output.
They can be driven directly from an internal combustion engine.
Ejector or jet pumps work by making use of what effect?
The venturi effect
On the PRL we carry the Submersible Mini Ejector Pump. What are the advantages of this kind of pump? (7 answers)
Light and easy to handle.
They can be used in places where other types of pump cannot operate i.e. - pits basements.
They require little attention once set up and operating.
Are capable of pumping gases as well as liquids.
They have no moving parts.
They will work in oxygen deficient atmosphere.
The primary pump can be placed well away from the incident.
There are three kinds of gauges on the PRL’s pump. What are they?
Low pressure - output for main jets
High pressure - output for hose reel
Compound - displays positive pressure of incoming supply and negative pressure if over drawing the supply
What does CREFT stand for?
Creating the flow
Raising the water
Entry loss
Frictional resistance
Temperature
If required bar isn’t given by a branch operator, what bar should a pump operator give?
3 bar
Loss of supply from a pressure fed supply could be caused by what?
Failure of the supply itself, i.e. a fractured main or burst hose between the hydrant and the pump.
Over-running the water supply when working with soft suction.
(NOTE: This causes the hose to flatten and shuts off the supply. Easing back the throttle until the hydrant can feed the pump again should remedy this)
Increased pressure on the delivery side can be caused by what?
This symptom should be investigated at once as it implies a stoppage of some sort on the delivery side and may be due to:-
Kinks in the delivery hose.
Vehicles standing on or debris fallen onto delivery hose.
Blockage of jet by small stones which have passed through the pump.
(NOTE: The closing of a hand held branch will give increased delivery pressure and the gauges must be closely monitored to ensure that other branches do not receive excessive pressure)
Decreased pressure on the delivery side can be caused by what?
Delivery hose burst.
Hand controlled branches being opened up.
When working from open water, if the pump fails to prime what two readings might you expect to see on the compound gauge?
No or high vacuum reading
