9. Fire pump theory

Question 1

__ pumps are self priming, deliver a definite volume of water or air, and exhaust air from the pump and deliver water.

Answer 1

Positive displacement pump

Constant flow machines

Question 2

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___ pumps operate using a piston they moved back and forth in a cylinder.

Answer 2

Piston

Question 3

This pump is classified as a non-positive displacement pump as it does not pump a definite amount of water with each at Revolution.

Answer 3

Centrifugal pump

Question 4

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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__

Answer 4

Volute

Question 5

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Three main factors influence a centrifugal fire pumps discharge pressure:

Answer 5

Amount of water being discharge

speed at which the impeller is turning

pressure of water when it enters the pump from a pressurize source

Question 6

Two basic types of centrifugal pumps are used by the fire service

Answer 6

Single stage and multi stage

Question 7

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.

Answer 7

100%

150psi

Question 8

__ valve are essential to the operation of a multistage pump that permits the flow of water in one direction only

Answer 8

Clapper or check valve

Question 9

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.

Answer 9

Lantern or slinger ring

Question 10

The piping system and the fire pump itself must be capable of withstanding a hydrostatic test of __ psi before being placed into service.

Answer 10

500 psi

Question 11

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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.

Answer 11

2 1/2 inch

Question 12

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.

Answer 12

3 inches

3 seconds

Question 13

Pressure control device must operate within __ seconds after the discharge pressure rises and restrict the pressure from exceeding __ psi above the set level.

Answer 13

3-10 sec

30 psi

Question 14

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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.

Answer 14

10 psi

Question 15

The electronic governor also features cavitation protection by returning the engine to idle when intake pressure drops below __ psi

Answer 15

30 psi

Question 16

A throttle is used to increase or decrease the speed of the engine that powers the fire pump. There are several types of the throttles available, including a __, That can be turned clockwise or counterclockwise to achieve the required pressure.

Answer 16

throttle knob also called a vernier