Chapter 10 Fire Pump Theory

Question 1

Positive displacement pumps have largely been replaced by ___ for use as the main fire pump on modern fire apparatus.

Answer 1

Centrifugal pumps

Question 2

Positive displacement pumps are used as ___ devices to get water into centrifugal pumps during drafting operations.

Answer 2

Priming

Question 3

The two basic types of positive displacement pumps are:

Answer 3

piston and rotary pumps.

Question 4

Piston positive displacement pumps may be:

Answer 4

single-acting or double-acting.

Question 5

The output of the piston positive displacement pump is determined by the size of the cylinder and the:

Answer 5

speed of the piston travel.

Question 6

The capacity of a piston positive displacement pump is usually determined by the size of the:

Answer 6

cylinder.

Question 7

Rotary positive displacement pumps are the ___ of all fire apparatus pumps in design.

Answer 7

simplest

Question 8

Rotary positive displacement pumps are now used as:

Answer 8

small-capacity, booster-type pumps, low-volume high pressure pumps, and priming pumps.

Question 9

The total amount of water that can be pumped by a rotary gear pump depends on the size of the ___ and the speed of rotation.

Answer 9

pockets in the gears

Question 10

Rotary vane pumps are constructed with moveable elements that automatically compensate for:

Answer 10

wear.

Question 11

The centrifugal pump is classified as a ___ because it does not pump a definite amount of water with each revolution.

Answer 11

nonpositive displacement pump

Question 12

The centrifugal pump imparts ___ to the water and converts it to pressure within the pump itself.

Answer 12

velocity

Question 13

The ___ of the centrifugal pump transmits energy in the form of velocity to the water.

Answer 13

impeller

Question 14

The ___ of the centrifugal pump collects the water and confines it in order to convert the velocity to pressure.

Answer 14

casing

Question 15

The ____ of the centrifugal pump is a water passage that gradually increases in cross-sectional area as it nears the pump discharge outlet.

Answer 15

volute

Question 16

The impeller in a centrifugal pump rotates very rapidly within the casing, generally from ___ rpm.

Answer 16

2,000 to 4,000

Question 17

The volume capacity of the pump is dependent on the size of the ___ of the impeller: The greater it is, the greater the flow capacity.

Answer 17

eye

Question 18

Which of the following is NOT a factor that influences a centrifugal fire pump’s discharge pressure?

Answer 18

A. Amount of water being discharged
B. Speed at which the impeller is turning
C. Size of the volute and impeller inside the pump*
D. Pressure of water when it enters the pump from a pressurized source

Question 19

What is changeover?

Answer 19

The process of switching between the pressure and volume position

Question 20

SOPs in some departments specify that the transfer valve stay in the pressure position until it is necessary to supply more than ___ the rated volume capacity of the pump.

Answer 20

one-half

Question 21

Most manufacturers specify that the pump may remain in the pressure system until it is necessary to flow more than ___ of the rated volume capacity.

Answer 21

two-thirds

Question 22

Most manufacturers recommend that the transfer valve should be operated at a maximum pressure of:

Answer 22

50 psi (350 kPa).

Question 23

While the parallel (volume) position may make it difficult to attain the desired pressure, it can supply ___ percent of the rated volume capacity at ___ psi (kPa).

Answer 23

100%, 150 psi (1 000 kPa)

Question 24

Any increase in the space between the pump casing and the hub of the impeller lessens the pump’s effectiveness. This opening is usually limited to ___ or less.

Answer 24

0.01 inch (0.25 mm)

Question 25

To restore pump capacity without replacing the pump itself, replaceable wear rings (or ___ rings) are provided in the pump casing to maintain the desired spacing.

Answer 25

clearance

Question 26

Packing rings are used to make a seal at the point where the shaft passes through the:

Answer 26

pump casing.

Question 27

The most common type of packing material is made of rope fibers impregnated with:

Answer 27

graphite or lead.

Question 28

As packing rings wear with the operation of the shaft, the ___ can be tightened and the leak controlled.

Answer 28

packing gland

Question 29

Which of the following are supplied to provide cooling and lubrication between the packing rings and shaft?

Answer 29

Lantern rings

Question 30

A small amount of ___ should leak out around the packing and prevent excessive heat buildup.

Answer 30

water

Question 31

If the pump is operated ___ for any length of time, it can damage the shaft.

Answer 31

dry

Question 32

Pumps equipped with ___ will not drip and will not require adjustment.

Answer 32

mechanical seals

Question 33

____ of mechanical seals may cause damage that necessitates immediate and complicated repair.

Answer 33

Freezing

Question 34

Which pumps are powered by a gasoline or diesel engine independent of an engine used to drive the vehicle?

Answer 34

Auxiliary engine-driven pumps

Question 35

Which pumps have power diverted from the rear axle by shifting of a gear and collar arrangement inside the gear box?

Answer 35

Midship pumps

Question 36

Which pumps can obstruct air flow through the vehicle's radiator and contribute to engine overheating?

Answer 36

Front-mount pumps

Question 37

Which pumps change pressure when the driver changes the vehicle speed?

Answer 37

Power take-off driven fire pumps

Question 38

Which pumps do not have the ability to pump-and-roll?

Answer 38

Midship pumps

Question 39

Which pumps provide more even weight distribution on the apparatus chassis?

Answer 39

Rear-mount pumps

Question 40

Which pumps are supplied power through the use of a split-shaft gear case located in the drive line between the transmission and the rear axle?

Answer 40

Midship pumps

Question 41

Which pumps allow the apparatus to have more compartment space for tools and equipment?

Answer 41

Rear-mount pumps

Question 42

Which pumps are powered by special fuels such as jet fuel?

Answer 42

Auxiliary engine-driven pumps

Question 43

Which pumps are used on ARFF vehicles, wildand fire apparatus, and portable fire pumps?

Answer 43

Auxiliary engine-driven pumps

Question 44

Which pumps must be mounted correctly for dependable and smooth operation?

Answer 44

Power take-off driven fire pumps

Question 45

Which pumps are more susceptible to freezing in cold climates?

Answer 45

Front-mount pumps

Question 46

Which pumps are mounted between the front bumper and the grill?

Answer 46

Front-mount pumps

Question 47

Which pumps require that the clutch be disengaged and the road transmission be placed in neutral to prevent damage to the gears?

Answer 47

Midship pumps

Question 48

Which pumps are driven by a driveshaft that is connected to the PTO on the chassis transmission?

Answer 48

Power take-off driven fire pumps

Question 49

Which pumps are ideal for pump-and-roll operations?

Answer 49

Auxiliary engine-driven pumps

Question 50

Which pumps offer the maximum amount of flexibility?

Answer 50

Auxiliary engine-driven pumps

Question 51

Which pumps are mounted laterally across the frame behind the engine and transmission?

Answer 51

Midship pumps

Question 52

Which of the following is NOT a component of a piping system?

Answer 52

A. Impellers B. Pump drains* C. Intake piping D. Discharge piping

Question 53

Which of the following is NOT a material used to construct piping systems?

Answer 53

A. Brass B. Rubber* C. Cast iron D. Stainless steel

Question 54

Piping systems must be able to withstand a hydrostatic test of ___ psi (kPa) before being placed into service.

Answer 54

500 psi (3 450 kPa)

Question 55

Piping that connects the pump and the onboard water tank is called:

Answer 55

intake piping.

Question 56

Intake piping should be sized so that pumpers with a capacity of 500 gpm (1 900 L/min) or less should be capable of flowing ___ gpm (L/min) from the booster tank.

Answer 56

250 (950 L/min)

Question 57

Intake piping should be sized so that pumpers with a capacity greater than 500 gpm (1 900 L/min) should be capable of flowing at least ___ gpm (L/min) from the booster tank.

Answer 57

500 gpm (1 900 L/min)

Question 58

Intake piping may be as large as ___ inches (mm) in diameter.

Answer 58

4 inches (100 mm)

Question 59

Pumps that have a capacity of ____ gpm (L/min) or greater may require more than one large intake connection at each location.

Answer 59

1,500 gpm (6 000 L/min)

Question 60

Apparatus with a rated pump capacity of 750 gpm (2 850 L/min) or greater must be equipped with at least ___ 2½-inch (65 mm) discharge(s).

Answer 60

two

Question 61

Apparatus with a rated pump capacity less than 750 gpm (2 850 L/min) are only required to have ___ 2½-inch discharge(s).

Answer 61

one

Question 62

All discharge valves should be designed so that they are easily operable at pressures of up to:

Answer 62

250 psi (1 724 kPa).

Question 63

The tank fill line:

Answer 63

allows the tank to be filled without making any additional connections when the pump is being supplied from an external supply source.

Question 64

Valves control most of the ___ lines from the pump.

Answer 64

intake and discharge

Question 65

Valves must be:

Answer 65

airtight.

Question 66

Which types of valves permit full flow through the lines with a minimum of friction loss?

Answer 66

Ball-type valves

Question 67

Which types of valves display readouts of how far the valve is opened?

Answer 67

Hydraulically, pneumatically, or electrically controlled valves

Question 68

Which types of valves are most commonly used on large-diameter intakes and discharges?

Answer 68

Gate or butterfly valves

Question 69

Gate valves are most often operated by:

Answer 69

a handwheel.

Question 70

Butterfly valves are most often operated by:

Answer 70

quarter-turn handles.

Question 71

Which types of valves indicate on the panel which direction to operate the switch in order to open or close the valve?

Answer 71

Hydraulically, pneumatically, or electrically controlled valves

Question 72

Automatic pressure control devices must operate within ___ seconds after the discharge pressure rises.

Answer 72

3 to 10

Question 73

Automatic pressure control devices must not allow the pressure to exceed ___ psi (kPa) above the set level.

Answer 73

30 psi (200 kPa)

Question 74

Which types of automatic pressure control devices are sensitive to pressure change and have the ability to relieve excessive pressure within the pump discharge?

Answer 74

Discharge pressure relief valves

Question 75

Which types of automatic pressure control devices regulate pressure on centrifugal pumps?

Answer 75

Pressure governors

Question 76

Which types of automatic pressure control devices are intended to reduce the possibility of damage to the pump and discharge hoselines caused by water hammer?

Answer 76

Intake pressure relief valves

Question 77

Which types of automatic pressure control devices are quick to react to overpressure conditions, but are somewhat slower to reset back to "all-closed" positions?

Answer 77

Discharge pressure relief valves

Question 78

Which types of automatic pressure control devices fit onto the carburetor or throttle link and reduces or increases the engine speed under the control of a rod connected to a piston in a water chamber?

Answer 78

Piston assembly governors

Question 79

Which types of automatic pressure control devices may be attached to either a regular or an auxiliary throttle?

Answer 79

Pressure governors

Question 80

Which types of automatic pressure control devices take a short time for the pump to return to normal operation?

Answer 80

Discharge pressure relief valves

Question 81

Which types of automatic pressure control devices should be set to open when the intake pressure rises more than 10 psi (70 kPa) above the desired operating pressure?

Answer 81

Intake pressure relief valves

Question 82

Which types of automatic pressure control devices use a pressure-sensing element connected to the discharge manifold to control the action of an electronic pump amplifier that compares pump pressure to an electrical reference point?

Answer 82

Electronic governors

Question 83

Which types of automatic pressure control devices relieve excess pressure that is generally caused by shutting down one or more operating hoselines?

Answer 83

Pressure governors

Question 84

Which types of automatic pressure control devices have an adjustable spring-loaded pilot valve that actuates the relief valve to bypass water from the discharge to the intake chamber of the pump?

Answer 84

Discharge pressure relief valves