Chapter 8: Fire Service Pump Design Flashcards
(186 cards)
1
Q
Most modern apparatus still utilize some form of this type of pump as a secondary mechanism for drafting:
A
Positive Displacement Pump
2
Q
The process of drafting is based on what principle of pressure?
A
The 2nd principle:
Pressure applied on a confined liquid from an external source will be transmitted equally in all directions throughout the liquid without a reduction in magnitude
3
Q
What is the operating principle of a piston-type pump?
A
A piston moves back and forth inside a cylinder
4
Q
Which piston pumps are not able to produce a usable fire stream because no water flows on the return stroke?
A
Single-acting piston pump
5
Q
This piston pump has 2 additional valves that enable the pump to receive and discharge water on each stroke of the piston?
A
Double-acting piston pump
6
Q
The output capacity of a piston pump is determined by:
A
The volume of the cylinder and the speed of the piston travel
7
Q
These pumps provided a more uniform discharge because their cylinders were arranged to reach their peak flows at different points in the cycle:
A
Multicylinder piston pumps
8
Q
What design elements were present on the cylinder of piston pumps that were particularly common on Ahrens-Fox pumpers?
A
A pressure dome
9
Q
The piston pump has not been used as the primary fire pump since the:
A
1950’s
10
Q
In addition to the problems of a pulsating fire stream, piston pumps are very susceptible to:
A
Wear and tear, thus making them maintenance intensive
11
Q
What pumps were commonly used in the ’60s and ’70s for high-pressure, low-volume applications?
A
John Beam high-pressure pumps
12
Q
The John Beam high-pressure pumps provided pressures up to ____ psi for high-pressure fog lines that typically flowed less than ___ gpm:
A
1,000 psi
15 gpm
13
Q
Where would you find high-pressure, low-volume pumps in the fire service today?
A
Wildland firefighting
14
Q
This type pump has the simplest operational design of all fire pumps:
A
Rotary-type positive displacement pumps
15
Q
What type of pump do most modern fire apparatus use to today as a priming pump for the fire pump?
A
Rotary-type positive displacement pump
16
Q
What are the 2 styles of rotary-type positive displacement pumps are there?
A
Rotary gear
Rotary vane
17
Q
This rotary-type pump consists of 2 tightly meshed gears that rotate inside a water tight case:
A
Rotary gear
18
Q
The rotary gear pump is a positive displacement pump because:
A
Each pocket in the gears contains a fixed volume
19
Q
What does the rotary gear pumps capacity depend on?
A
The size of the pockets formed by the gears and the speed of the gear rotation
20
Q
To minimize damage to the pump casing, most rotary gear pumps have gears made of:
A
Bronze or other soft metal
21
Q
What types of metals are used for the pump casing of rotary gear pumps?
A
Cast iron or steel
22
Q
This rotary pump has a set of vanes that are free to move within the slot where they are mounted:
A
Rotary vane pump
23
Q
The rotary vane pump has a rotor that is mounted _________ inside the pump casing. The distance between the rotor and the casing is much greater at the _________ area:
A
Off-center
Intake
24
Q
What self-adjusting feature does the rotary vane pump possess that makes it much more efficient at pumping air than the rotary gear pump?
A
When the surface of the vane that contacts the casing becomes worn, centrifugal force causes the vane to extend further, thus automatically maintaining a tight fit
25
As with all positive displacement pumps, the air being evacuated from the intake side causes a reduced pressure. When this happens, what forces water into the pump?
Atmospheric Pressure
26
This is the primary fire pump on all fire apparatus today:
Centrifugal pump
27
Why is the centrifugal pump not considered a positive displacement pump?
Because it does not pump a definite amount of water with each revolution
28
Centrifugal pumps impart _________ to water and then converts it to ________ within the pump casing:
Velocity
| Pressure
29
What are the disks called inside of centrifugal pumps?
Impellers
30
On a centrifugal pump, the faster the impeller turns, the more ________ it imparts to the water:
Velocity
31
In a centrifugal pump, the amount of pressure created depends on:
The speed of the impeller
32
What are the 2 primary parts of a centrifugal pump?
The impeller and the casing
33
What speeds of the impeller are common depending on the design of the pump and the amount of pressure or volume desired?
2,000 to 4,000 rpms
34
The passage to the pump's discharge on a centrifugal pump is called the:
Volute
35
What 3 main factors influence a centrifugal fire pumps discharge pressure?
1. The amount of water being discharged
2. The speed at which the impeller is rotating
3. The pressure of the water entering the pump
36
If all other factors remain constant, the mount of discharge pressure a centrifugal pump can develop is directly dependent upon:
The volume of water it is discharging
37
The greater the volume of water being flowed, the ______ the discharge pressure will be:
Lower
38
The increase in pressure is approximately equal to the _______ of the change in impeller speed:
Square
39
If all other factors remain constant, doubling the speed of the impeller will __________ the discharge pressure:
Quadruple
40
Why can water flow freely through a centrifugal pump even if it is not turning?
Because it has no mechanical blockage between the intake and discharge sides of the pump
41
The centrifugal pumps's ability to create pressure on water is also due in part to water's being:
Incompressible
42
Why can a centrifugal not pump air out of the discharge?
Because air is compressible
43
What are the 2 basic types of centrifugal pumps used in the fire service?
Single-stage and two-stage
44
A single-stage centrifugal pump only contains 1 ______ within its pump casing?
impeller
45
In the days when most apparatus were powered by gasoline engines, the volume capacity of single stage pumps were limited to ________ gpm:
1,250 gpm
46
Modern pumpers with diesel engines and single-stage pumps are capable of producing up to _______ gpm:
2,000 gpm
47
To minimize the stresses and lateral thrust created by large quantities of water entering the eye of the impeller, engineers designed a:
Double intake impeller
48
What is developed as the water is delivered to the discharge outlet because the impeller turns at a very high rate?
Radial thrust
49
Radial thrust is canceled by:
Removing the water at 2 places and directing it in opposite directions
50
What are the 3 characteristics of two-stage centrifugal pumps?
1. They are usually mounted on a single shaft
2. They are driven by a single power source
3. They are usually identical in size and design and have the same capacity
51
In two-stage pumps, when working in parallel impellers are able to deliver more:
GPM
52
In two-stage pumps, when working in series the impellers are able to deliver more:
Pressure
53
In parallel mode, each of the impellers can deliver the pump's rated pressure rated pressure while flowing _____ of its rated capacity:
Half
54
The volume (parallel) position is most often used when:
Pumping multiple or large diameter supply lines or feeding master stream devices
55
Depending on the manufacturer, the first impeller while pumping in series discharges from ____ to ____ percent of the volume capacity through the changeover valve and into the eye of the 2nd impeller:
50 to 70 percent
56
The pressure (In series) position is most often used:
When supplying attack lines, especially when operating from the apparatus water tank
57
The process of switching between pressure and volume mode is sometimes referred to:
Changeover
58
Historically, the fire service has taught the rule of thumb that the changeover valve stays in the _______ position until it is necessary to to supply more than ________ the rated volume capacity of the pump:
Pressure position
| 1/2
59
Advances in design and efficiency have allowed most pump manufacturers to specify that the pump may remain in pressure mode until it is necessary to flow more than ___ percent of the rated volume capacity:
70 percent
60
If the pump operator is not sure which position to use, which one should he default to?
Volume (parallel) position
61
In parallel position, the pump will be capable of supplying _____ percent of the rated volume at ____ psi:
100%
| 150 psi
62
In most cases, the recommended maximum pressure to perform changeover should not exceed ____ psi:
75 psi
63
What should the driver do when idling down to perform changeover is necessary?
Coordinate it with the fire attack group
64
Switching from volume to pressure mode immediately _________ the discharge pressure:
Doubles
65
Newer pumps utilize power-operated changeover valves that can be driven by one of these ways:
1. Electricity
2. Pressure
3. Vacuum (Gasoline powered vehicles)
4. Water pressure itself
66
Many power-operated changeover valves operate at pressures as high as:
200 psi
67
Centrifugal pumps with more than 2 impellers have and continue to be used most often found in fire departments that:
Protect tall high-rise structures
68
The centrifugal pumps that are used to protect high-rises and have as many as 4 impellers are capable of producing pressures up to ______ psi:
1,000 psi
69
What is the most important consideration when deciding how and where a pump is to be mounted on an apparatus?
The pump's expected use
70
What are the most common pump drive arrangements on modern fire apparatus?
1. Auxiliary-engine driven pumps
2. Power take-off (PTO) driven pumps
3. Front-mount driven pumps
4. Midship transfer driven pumps
5. Rear mount pumps
71
Auxiliary-engine pumps receive their power from:
A separate engine independent of the engine used to propel the truck
72
Auxiliary-engine driven pumps are more likely to be found in these applications:
1. ARFF apparatus
2. Wildland trucks
3. Mobile water supply trucks
4. Trailer-mounted fire pumps
5. Portable fire pumps
73
Auxiliary-engine driven pumps are preferred when the department wants either the ability to:
Pump and roll or the ability to place a fire pump remote from the truck
74
Pump and roll operations are common in:
ARFF and Wildland firefighting
75
Auxiliary-engine driven pumps that are used on wildland trucks, mobile water supply trucks, and portable pumps are typically powered by engine with less than ____ horse power and a pumping capacity of _____ gpm or less:
50 horse power
| 400 gpm or less
76
Auxiliary-engine driven pumps that are used on ARFF trucks, structural fire fighting trucks, and trailer-mounted applications tend to be large-capacity pumps of up to ____ gpm and engines capable of up to ____ horse power:
4,000 gpm
| 500 horse power
77
What is the one inherent drawback to auxiliary-engine driven pumps?
Having a second engine on the truck creates additional maintenance work
78
The optimum design for a PTO pump installation includes:
A minimum of angles in the drive shaft between the PTO connection and the pump casing
79
The PTO connection receives its power from an _____ ______ in the chassis transmission:
Idler gear
80
If the truck is designed for pump and roll operations, what should be installed and where:
A pressure gauge should be installed in the cab
81
While operating the truck in a pump and roll application with hose lines in operation, the driver should use this instead of the speedometer?
The pressure gauge
82
The conventional PTO arrangement unit limited the capacity of the pump to about ____ gpm:
500 gpm
83
In recent years, some pump manufacturers have developed _______ ________ power take-offs that permit the installation of pumps as large as ______ gpm:
1,500 gpm
84
What other devices may use PTO for operation?
1. Electric generators
2. Rescue tools
3. Air compressors
85
To accommodate a front-mount pump, extensions are added to the chassis frame rails and the front bumper is moved forward ___ to ____ feet from its normal position:
3 to 5 feet
86
The gear box that drives the front-mount pump has a ratio that is set to match the:
Torque curve of the engine to the rotation speed for the impeller to deliver the pump's rated capacity
87
The most common gear ratios for front-mount pumps are between:
1:1 and 2 1/2:1
88
Where is the front-mount pump engaged and controlled from?
The pump itself
89
Because the operating lever that engages a front-mount pump is located at the pump, what and where should be installed to alert the driver the pump is engaged?
A warning light in the cab
90
Front-mount pumps are preferred by departments that frequently:
Draft from static water sources
91
What are 2 disadvantages of front-mount pumps?
1. They are exposed and susceptible to freezing
| 2. They are in a vulnerable position in the event of a collision
92
How are front-mount and PTO driven pumps alike?
They can both be used in pump and roll applications
93
What is the most common drive and mounting arrangement for modern pumping apparatus?
Midship-transfer-driven pump
94
What supplies power to the midship-transfer-driven pump?
The transfer case
95
Where is the transfer case located?
In the drive line between the transmission and the rear axle
96
How are front-mount pumps and midship-transfer pumps alike?
For both, a gear ratio matches the engine torque curve to the speed of rotation required for the pump impeller to deliver the rated capacity
97
How much faster does the impeller of a midship-transfer pump rotate in reference to the engine speed?
1 1/2 to 2 1/2 times faster
98
Midship-transfer driven pumps used in today's fire service commonly range in capacity from ______ to _______ gpm:
500 to 3,500 gpm
99
Where are the midship-transfer controls located?
Inside the cab
100
On modern apparatus, the midship-transfer control is operates the transfer case by one of the following:
1. Electrical
2. Hydraulic
3. Pneumatic
101
Generally, what gear will most likely be used when using a midship-transfer pump?
The highest gear
102
Who will specify which gear to use for midship-transfer pumps?
The manufacturer
103
What is one way to check if the transmission on a midship-transfer pump is in the correct gear?
By observing the speedometer reading after the pump is engaged
104
After the pump is engaged on a midship-transfer pump, when observing the speedometer, what will the reading be to indicate it is on the correct gear?
It will read between 10 and 15 mph
105
What is a disadvantage of midship-transfer pumps?
They cannot be used for pump and roll
106
What are 2 advantages of having a rear mounted pump?
1. Distributes weight more evenly on the chassis
| 2. More compartment space
107
What is a disadvantage of rear mount pumps?
The operator may be more exposed to oncoming traffic
108
How can rear mount pumps be driven?
1. Split-shaft transmission
| 2. PTO
109
NFPA 1901 requires all fire truck pumping systems to have some sort of pressure control device. What are the requirements of this device?
1. The device will operate within 3 to 10 seconds after the discharge pressure rises at least 30 psi above the set level
2. A yellow indicator light on the pump panel must illuminate
110
What are the 2 basic pressure control devices used on fire trucks?
1. Relief valves
| 2. Pressure governor
111
What are pressure relief valves intended to reduce?
The possibility of water hammer damaging the pump and hose lines when valves or nozzles are closed to quickly
112
What are the 2 basic types of pressure relief valves?
1. Those that relieve excess pressure on the intake side of the pump
2. Those that relieve excess pressure on the discharge side of the pump
113
NFPA 1901 requires all fire pumps that are not equipped with a pressure governor to be equipped with this as an integral part of the pump:
A discharge pressure relief valve
114
The most common design of discharge pressure relief valves use:
An adjustable spring-controlled pilot vlave
115
The operator should remember that while discharge pressure relief valves react quickly to over-pressure conditions, they are somewhat slower to:
Reset to all-closed positions
116
What are the 2 common designs for intake pressure relief valves?
1. Supplied as an integral part of the pump intake by the manufacturer
2. Add-on device that is attached to the pump intake connection
117
Is is generally recommended that the intake relief valves be set to open when the intake pressure rises more than ___ psi above the desired operating pressure
10 psi
118
The basic operational principle of the pressure governor is to:
Regulate the engine's power output to match the pump's discharge requirements
119
What are the 2 settings on a mechanical pressure governor?
1. Draft (Closed)
| 2. Hydrant (Open)
120
Where does the excess water go when the mechanical pressure governor is in the Draft position?
Returns it to the intake side of the pump
121
Where does the excess water go when the mechanical pressure governor is in the Hydrant position?
Onto the ground through a drain line
122
Most modern fire trucks have this type of pressure governor:
Electronic pressure governor
123
An electronic pressure governor has a control knob that the operator can set to maintain any pressure above ____ psi:
50 psi
124
What does the electronic pressure governor do anytime the pump discharge pressure drops below 50 psi?
It returns the engine to idle
125
The electronic pressure governor protects the pump against cavitation by returning the engine to idle any time the intake pressure drops below ____ psi:
30 psi
126
What major advantage does electronic pressure governors have over mechanical pressure governors?
Electronic pressure governors adjust the engine rpms when a discharge is closed, but maintains a steady discharge pressure on the lines that are still flowing. Mechanical pressure governors briefly lowers all discharge line working pressures.
127
To draft water from a static water source, the pump must first be able to create a _______ pressure within the pump and intake hose than exists in the _______. This is referred to as a _______ ________:
Lower
Atmosphere
Partial Vacuum
128
What are the 3 categories that primer pumps fall into?
1. Vacuum
2. Exhaust
3. Positive displacement pumps
129
What is the oldest and simplest type of primer pump?
Vacuum primer
130
What 2 potentially dangerous conditions does the check valve between the engine manifold and the pump intake protect against?
1. It prevents explosive gases from the intake intake manifold from being drawn into the pump and damaging it
2. It prevents water from being drawn through the pump and into the intake manifold of the engine
131
Because engine vacuum is at the maximum at ____ speed, the primer works best at ____ engine rpms:
Idle
| Low
132
What do exhaust primers and vacuum primers have in common?
They are both found on older fire trucks
133
The exhaust primer works on the same principle as a:
Foam eductor
134
Exhaust primers require ____ engine rpm to generate the exhaust gases' maximum velocity:
High
135
What are 2 disadvantages of exhaust primers?
1. Not very efficient
| 2. Require a great deal of maintenance
136
Most modern fire trucks use these types of primers:
Positive displacement primers
137
The rotary vane primer requires a relatively _____ rpm compared to a rotary gear primer
High
138
Nearly all modern fire trucks have ______ motor driven primers:
Electric
139
What are 2 advantages of electric motor driven positive pressure primers?
1. They allow max flexibility in mounting
| 2. Operate effectively regardless of engine speed
140
Most positive displacement primers use an oil supply or other fluid to serve what 2 purposes?
1. It seals the gaps and any irregularities inside the pump to improve the efficiency of the primer
2. It acts as a preservative and minimizes deterioration of the metal parts
141
NFPA 1901 requires all fire pump trucks to be equipped with a supplementary heat exchanger cooling system, more commonly called an:
Auxiliary cooling system
142
What are the 2 types of auxiliary coolers?
1. Marine type
| 2. Immersion type
143
What is the measured distance between the pump casing and hub of the impeller limited to?
1/100th of an inch or less
144
The operator can check the pump temperature by:
Placing a hand on the direct pump intake pipe of the pump
145
The most common type of packing material is made of:
Rope fibers impregnated with graphite or lead
146
What 4 components make up the water distribution system of a fire truck and the pump?
1. Intake piping
2. Discharge piping
3. Pump drians
4. Valves
147
Most piping systems on a fire truck are constructed of:
Cast iron, brass, stainless, or galvanized steel
148
The piping system (as well as the pump itself) must be able to withstand a hydrostatic test of ___ psi before being placed into service:
500 psi
149
To minimize pressure loss within the apparatus, all piping and hoses should:
Run as straight as possible with minimum bends or turns
150
What are the 2 primary routes water may enter a fire pump?
1. Through piping that connects the pump and the water tank supply
2. Piping that connects the pump to an external supply
151
NFPA 1901 states that piping should be sized so that pumpers with a capacity of ____ gpm or less should be capable of flowing _____ gpm from their booster tank. Pumpers with capacities greater than ____ gpm should be able to flow at least ___ gpm from the tank:
500 gpm
250 gpm
500 gpm
500 gpm
152
Because any air trapped in the pump during priming can prevent successful drafting from a static water supply source, all intake pipes to a centrifugal pump normally are located _____ the eye of the impeller, with no part of the piping ______ the impeller. The single exception to this may be the_________ -_______-______ line, where the water moves to the pump under the natural pull of gravity:
Below
Above
Tank-to-pump
153
As intake piping nears the pump, it typically tapers to a ________ cross section which eliminates the _______ that may occur in water that flows through circular piping:
Square
| Vortex
154
Front mounted and rear mounted large diameter intakes should be considered:
Auxiliary intakes. They are not always able to provide the supply needed to flow full capacity due to all of the bends and turns in them
155
Most auxiliary intake openings are gated and have a female ______ inch hose coupling:
2 1/2 inch
156
NFPA 1901 requires the auxiliary piping to be at least ____ inches in diameter:
2 1/2 inches
157
NFPA 1901 requires all valves on discharge piping to be designed so they are easily operated at pressures of up to ____ psi:
250 psi
158
According to NFPA 1901, apparatus must have enough 2 1/2 inch or larger discharge outlets to:
Flow the rated capacity of the fire pump
159
To meet NFPA 1901 requirements, all fire apparatus with a pump capacity of ____ gpm or greater must be equipped with at least ___ 2 1/2 inch discharges. Pumps rated at less than ____ gpm are required to have ___ 2 1/2 inch discharges. Most fire apparatus have one 2 1/2 inch discharge for every _____ gpm of rated pump capacity:
```
750 gpm
2
750 gpm
1
250 gpm
```
160
Discharges larger than ______ inches must not be located on the pump panel:
2 1/2 inch
161
NFPA 1901 requires that discharges to which 1 1/2, 1 3/4, and 2 inch hand lines are attached must be supplied by at least ____ inch piping:
2 inch
162
A 3 inch discharge with a full flow valve easily can supply all of the water that a single ____ inch supply hose can carry:
5 inch
163
In the case of a 2-stage pump, the tank fill line gets its flow from which stage?
First stage
164
NFPA 1901 requires apparatus with a water tank of of less than _____ gallons have a tank fill line at least ___ inches in diameter. Apparatus with tanks of _____ gallons or more must have a fill line of at least ____ inches:
1,000 gallons
1 inch
1,000 gallons
2 inches
165
NFPA 1901 requires that all valves on intakes or discharges that are ___ inches or greater to be equipped with ______-______ valve controls. This prevents movements from the fully open to the fully closed position (or vise versa) in less than ____ seconds:
3 inches
Slow-acting
3 seconds
166
The most common valve design on a fire engine is the:
Ball valve
167
Newer apparatus have valves that can be controlled in one of 3 ways:
1. Hydraulically
2. Pneumatically
3. Electrically
168
Fire apparatus also use gate or butterfly valves, most commonly on:
Large diameter intakes and discharges
169
Drains must be supplied at the _____ point on the pump and the _______ point on each line connected to it:
Lowest
| Lowest
170
When using the pump drains, the operator should do this to allow air to replace the draining water. If not, the resulting vacuum will hold some water in the pump
Open a discharge valve
171
As a minimum, NFPA 1901 requires the pump operator's panel to have the following controls and instruments:
1. Master intake gauge
2. Master discharge gauge
3. Tach
4. Engine coolant temp gauge
5. Engine oil pressure gauge
6. Pump overheat indicator
7. Voltmeter
8. Discharge gauges
9. Engine throttle
10. Primer control
11. Tank to pump valve
12. Tank fill valve
13. Tank level indicator
172
What characteristics must the master intake gauge possess?
1. Must be able to read positive and negative pressure
2. Calibrated from 0 to 600 for positive pressure
3. Calibrated from 0 to 30 inches of mercury for vacuum
173
The master intake pressure gauge indicates this when the pump is operating from a pressurized supply source?
Residual pressure
174
When pumping from a draft, the master intake gauge indicates:
The amount of vacuum at the pump intake during priming or when operating from a draft
175
During drafting operations, as the vacuum reading approaches ____ inches mercury, the pump nears its maximum capacity and cannot supply any additional lines:
20 inches of mercury
176
The master discharge gauge must be calibrated to read up to _____ psi, and if the pumper is equipped to supply high-pressure streams, it may be calibrated up to ____ psi:
600 psi
| 1,000 psi
177
What is the most common type of engine throttle on a pump panel?
Rotating knob
178
What is the most common type of tank level indicating device?
Series of lights by 1/4 increments
179
While supplying the proper pressure to a hose line is important, ultimately the most important thing is to supply the proper:
Volume of water
180
NFPA 1901 allows flowmeters to be used instead of pressure gauges on all discharges ____ to ____ inches in diameter.
1 1/2 to 3 inches
181
Discharges that are ____ inches or larger may be equipped with flowmeters, but they must also have:
An accompanying pressure gauge
182
A flowmeter must provide readouts in increments of:
10gpm
183
What are the 2 types of flowmeter sensors?
1. Paddlewheel
| 2. Spring probe
184
Which of the 2 types of flowmeter sensors are relatively maintenance free?
The spring probe
185
Flowmeters should be accurate to a tolerance of:
+/- 3 percent
186
Each discharge equipped with a flowmeter has a digital readout display mounted within ____ inches of the valve control:
6 inches
