Flashcards in 9. Fire pump theory Deck (16)
__ pumps are self priming, deliver a definite volume of water or air, and exhaust air from the pump and deliver water.
Positive displacement pump
Constant flow machines
___ pumps operate using a piston they moved back and forth in a cylinder.
This pump is classified as a non-positive displacement pump as it does not pump a definite amount of water with each at Revolution.
The off center mounting of the impeller within the casing create a water passage of gradually increasing size as it nears the discharge outlet at the pump. This section of the__
Three main factors influence a centrifugal fire pumps discharge pressure:
Amount of water being discharge
speed at which the impeller is turning
pressure of water when it enters the pump from a pressurize source
Two basic types of centrifugal pumps are used by the fire service
Single stage and multi stage
In the parallel mode, the pump will be capable of supplying ___% of its rated capacity at ___ psi at 10 feet of left with 20 feet of suction hose while drafting.
__ valve are essential to the operation of a multistage pump that permits the flow of water in one direction only
Clapper or check valve
Heat developed by friction where the packing rings come into contact with the shaft. In order to overcome this a spacer known as a __ is supplied with the packing to provide cooling.
Lantern or slinger ring
The piping system and the fire pump itself must be capable of withstanding a hydrostatic test of __ psi before being placed into service.
As a minimum, all fire apparatus with a rated pump capacity of 750 GPM’s or greater must be equipped with at least two __ inch discharges.
2 1/2 inch
NFPA 1901 requires that all intake or discharges that are __ inches or greater be equipped with with slow acting valve controls. This feature prevents the valve movement from open to close in less than __ seconds.
Pressure control device must operate within __ seconds after the discharge pressure rises and restrict the pressure from exceeding __ psi above the set level.
It is generally recommended that the intake relief valve be set to open when the intake pressure rises more than __ psi above the necessary operating pressure.
The electronic governor also features cavitation protection by returning the engine to idle when intake pressure drops below __ psi