Pump Theory And Construction Flashcards
The overheat protection manager prevents the pump from overheating by__________?
Dumping water from the pump to the ground.
The gradually increasing size of the waterway __________ the velocity of the water thus enabling the pressure to__________ proportionately.
Decreases , build up
The inlet relief valve on the TFT intake ball valve is set to activate at______or lower?
1260 kpa
Which statement is correct?
• Centrifugal pumps take advantage of incoming pressure and add to it.
• Centrifugal pumps are not affected by incoming pressure.
• Centrifugal pumps can be used to reduce incoming pressure
Centrifugal pumps are self-priming
Centrifugal pumps take advantage of incoming pressure and add to it.
On a centrifugal pump water enters the impeller through the _______
Eye
A relay pump supplying 125mm hose rated to 1400 kPa cannot exceed ____
discharge pressure.
1260 kpa
When filling the booster tank be sure not to ________
Cavitate the pump
When pumping in a relay (as well as from a hydrant) the residual incoming pressure should not drop below _____
150 kpa
The priming pump is a ________ pump.
Positive displacement pump
What is the most commonly used drive on CFD engines?
The mid shift transfer drive configuration is used on most CFD apparatus to operate pumps. The system has the pump connected to the split shift transfer case located on the driveline between the transmission and the rear axle. This system is operated with the transmission in drive.
What is a PTO?
The Power Take Off Drives arraignment is powered by an idle gear in the transmission and is used primarily on the CFD to operate Aerial PTOs or Generator PTOs. Transmissions are placed in the neutral position when operating these PTOs.
Does CFD use a front mounted pump?
Yes. The front mounted pump configuration is commonly used for pump and roll operations, such as wild land firefighting. It has a few disadvantages: the pump is exposed to damage from a front end collision, as well as the pumps tend to freeze up quicker in colder climates due to being exposed to the elements.
What are the three main factors that greatly influence a centrifugal pump’s discharge pressure?
The amount of water being discharged.
The speed at which the impeller is turning.
The pressure that the water has when it enters the pump from a pressurized source.
At what temperature does the Overheat Protection Manager light turn red?
Once the water temperature reaches 180 degrees F.
At what temperature does the Overheat Protection Manager begin to dump water out of the body?
The system will begin to automatically dump water at 140 degrees F out of the pump body.
How can cavitation be described?
This is a condition where, in theory, water is being pumped out faster than water can enter the pump. This occurs when air bubbles travel across the impeller vanes and through the pump.
Switching from volume to pressure mode….
Never switch from volume to pressure mode when landlines are flowing.
Clapper valves…
The clapper valves are essential in a two stage pump. If they should stick open or closed, or get debris caught in them, the pump will not operate properly in pressure (series) mode.
What kpa is the optimum pump discharge pressure for maximum volume?
1000 kpa
As we increase the pressure, the capacity is reduced…
At 1700 kpa pump discharge pressure, the output volume is reduced to half. This is why it is important to keep friction losses to a minimum.
NFPA 1901 requires that all fire apparatus pumping systems be installed with a pressure relief system that…
must operate within 3-10 seconds after the discharge pressure rises at least 30 psi above the set level.
