Last 6th Month Flashcards
1
Q
The rotating weight of the unit is transferred through the thrust bearing, through the upper bridge, and through the______ ______ to the foundation
A
Stator frame
2
Q
On an umbrella unit, the thrust bearing is located:
A
Below the rotor
3
Q
The three typical types of thrust bearings are.
A
adjustable shoe, self equalizing and spring loaded
4
Q
The adjustable shoe thrust bearing uses a_______ under each of the shoes for adjusting the height and loading of the shoes.
A
Jack screw
5
Q
To install the thrust block, it is heated to a predetermined temperature and lowered over the shaft, again with the unit on jacks. The block is set on the________ the rigging removed, and the radial keys and keeper installed.
A
Thrust shoes
6
Q
With the thrust block still hot and installed on the shaft, the jacks are released to
A
allow the full weight of the unit to set the block in place against the keys
7
Q
Using the thrust bearing high pressure lubrication system, allows for both________and________ movement required during the alignment process.
A
Rotational; lateral
8
Q
As alignment deviates, loading on the guide bearings wil increase as wil_______ levels
A
Vibration
9
Q
Any increase in vibration from misalignment will decrease the_______ factor of operation in severe circumstances
A
Safety
10
Q
The concentricity of the stationary components can be checked by.
A
hanging a single tight wire to check plumb reference
11
Q
The tolerance for plumb of center of shaft run-out is_______ multiplied by the length of the shaft from the highest plumb reading to the lowest plumb reading in inches.
A
0.000025
12
Q
The tolerance for shaft straightness should not be more than______ inch from a straight line connecting the top and bottom reading point.
A
0.003
13
Q
The parallel misalignment between two shafts that occurs at the coupling between the generator and turbine shaft is called.
A
Offset
14
Q
Shaft dogleg is
A
angular misalignment of the turbine and generator shafts
15
Q
Plumb wires should be hung______
apart.
A
90° 
16
Q
The first preliminary check during the alignment process, is to loosen the mounting bolts on each leg of the upper bridge to check for
A
Soft foot
17
Q
One of the most important things to check before taking alignment readings is to make sure the
A
Shaft is free
18
Q
The procedure that is particularly useful during major overhauls is to temporarily install the upper and lower bridges and the head cover to check the concentricity of the stationary components with a single plumb wire and a(n):
A
Electric micrometer
19
Q
When the unit is centered the concentricity can be checked by taking______ readings at the turbine guide bearings, seal rings, generator air gap, etc.
A
Clearance
20
Q
Correcting dogleg between the generator and turbine shafts requires installing a shim pack between the
A
Coupling faces
21
Q
The second method used for aligning Hydrounits with Adjustable Shoe Thrust Bearings is using the adjustable feature of the shoes only to achieve equal:
A
Loading
22
Q
On Self Equalizing Thrust Bearings, one step in the procedure is to center the shaft in the_______ ________ housing and move the______of the shaft to make plumb.
A
Turbine bearing; top
23
Q
The final step in the alignment process is the installation and adjustment of the
A
Guide bearings
24
Q
To make the generator guide bearings concentric to the turbine guide bearing, the________ is used as a Reference
A
Shaft
25
When installing the turbine bearing, several______are used to prevent lateral movement.
Dowels
26
Although vertical Hydro-unit machines may be extremely large:
Close tolerances must be maintained
27
The vertical Hydro-unit machine that has the thrust bearing and upper guide bearing located above the rotor is called
Suspended type
28
On large low-speed vertical hydro-unit machines, the rotor poles are secured to the rim by
Driven tapered keys
29
On an adjustable-blade pump or propeller (Kaplan) type turbine, a hollow shaft is required on the electrical machine to
allow oil pipes to be carried through the shaft from the oil head at the
top of the unit to the turbine servomotor
30
On guide bearings, lubrication arrangements eliminate the need for an oll circulating system.
The designated oil level is usually about______
the length of the bearing above its lower end
1/3
31
Brakes are usually operated by compressed air at________ psi. When used as jacks, the brakes are operated by an oil pressure of_________psi
75-100; 1000-3500
32
High-pressure bearing lubrication is frequently used to reduce:
Breakaway torque
33
The high-pressure bearing lubrication pump assembly uses a_________ to prevent starting the machine (hydro-unit) until the pressure is approximately 1000 psi.
Pressure switch
34
Prior to erection of the unit, the turbine or pump runner and shaft are centered and supported in a position at a specified distance usually_______inch below the correct operating position.
1/4 to 3/4
35
During the alignment process, fins should be provided on the plumb bob to allow it to hang in a pail of heavy oil to dampen any swings and protect the plumb line from:
all strong air currents
36
Electric welding on any part of the machine is a serious hazard to bearings. A bearing surface can be damaged:
rapidly if welding current passes across it
37
In regards to Hydro-units, if possible all electric welding should be done
before bearings are assembled
38
The thrust bearing tub cooling coil should be water-tightness tested to a water pressure of ______% of normal working pressure.
150
39
Precautions should be taken during assembly of the thrust bearings to avoid:
All of the above
40
Segmental bearings made up of independently adjustable segments must be set to:
Proper elevation and clearance
41
To eliminate the possibility of shaft current. bearings and other parts should be;
Insulated
42
Check the insulation with a______
volt insulation meter, if the resistance is less than_______ohms inspect the insulation and make necessary corrections.
500; 20,000
43
Before drawing the couplings together, their mating surfaces must be in alignment, parallel, clean and free from burrs. The couplings must be drawn up:
Evenly to prevent distortion
44
Coupling bolt tension can be determined by an accurate measurement of the bolt:
Elongation
45
To prevent plumb wires from swaying and twisting, the finned weights should be immersed in pails of:
Oil
46
Check commutator________with a dial indicator rather than by visual observation
Run-out
47
Various instruments and relays and their associated equipment, wiring, piping and conduit should be carefully installed, making sure that it does
Not short-circuit the bearing insulation
48
The rotating parts of the machine must be in______ balance and may require the addition of weights to the rotor.
Dynamic
49
Before connecting the generator to the power system check.
Phase sequency
50
If an operational check of the shaft run-out is required, make it after the generator:
Is operating under full load
51
The best way to determine the correct running clearance in a plain-bearing installation is to
Consult manufacturer's charts and tables
52
The ability of bearing material to dissipate excessive heat generated during operation is called
Thermal conductivity
53
The ability of bearing material to flow slightly when loaded is called
Conformability
54
An advantage of grease compared to oil in lubricating a plain bearing is that
Newly applied grease forces old lubricants out
55
Discoloration in plain bearings is generally a symptom of
Excessive heat
56
Which of the following should be used to measure the running clearance of a plain bearing?
Feeler gauge
57
Which method should be used to remove moisture from a bearing shell after it has been cleaned?
Preheating
58
When building a plain bearing liner, coat the mandrel with_______ to keep molten babbit from clinging
White lead
59
What is the purpose of the grooves cut into a plain bearing liner?
Circulate lubricant
60
Which is the most likely cause of screeching from a plain bearing during operation?
Clearances are too tight
61
If you must leave your workplace temporarily, what care should you give a new, unmounted antifriction bearing?
Wrap it in oil-resistant paper
62
To prevent creeping of an inner bearing ring around the shaft, you should mount the inner ring with a(n)______fit
Interference
63
You can force an antifriction bearing into position on the shaft by using an arbor press or by impact, if the bearing has an O.D. Of
4in or less
64
A bearing is driven up a split tapered adapter by
Tightening a heavy-duty locknut
65
At approximately what temperature should you begin to suspect a bearing problem?
200° F
66
You clean an antifriction bearing before installation if it
Will be lubricated by automatic oil-mist
67
If the shoulder is too low when seating an antifriction bearing on the shaft the
Inner ring may distort
68
When inspecting a tapered shaft by blueing the gauge bore a(n)_______ % blueing transfer is acceptable.
80
69
When cold mounting an antifriction bearing, you must
lubricate the bearing bore and shaft with light oil
70
Which of the following is not an approved way to heat a roller bearing for a temperature mount?
Gas-operated torch
71
What is the correct tool to use when removing a locknut from an antifriction bearing installation?
A spanner
72
When you use a puller to remove a taper-mounted bearing, what should you do with the locknut?
Back the nut off several turns
73
An aluminum heating ring is designed for mounting and dismounting the inner rings of a_______bearing
Cylindrical roller
74
When you use an aluminum heating ring to expand a bearing, heat the ring to
500 °F
75
If you have cleaned and inspected an antifriction bearing but do not intend to reuse it immediately, how should you treat it before wrapping it in oil-resistant paper and storing it?
Fill it with grease
76
The two main methods of removing antifriction bearings are
Impact and heating
77
Which of the following is a correct way to remove an antifriction bearing with a diameter smaller than 4 in.?
Arbor press
78
The two important dimensions of a bearing puller are spread and
Reach
79
To remove a bearing, a splitter may be used with a(n)
Mechanical puller
80
Which of the following should not be used to clean an antifriction bearing when inspecting it?
Steam
81
Which type of bearing seal keeps out water, dirt, and contaminants most effectively?
Contact seal
82
Which type of antifriction bearing can tolerate the most internal misalignment?
Spherical roller bearing
83
The correct tolerance range for shafts from 2 to 4 in. in diameter is nominal to
-0.001in
84
When you lubricate bearings with grease, the actual lubricant is_______ which is held in suspension
Mineral oil
85
As a rule, the interval between lubrication renewals is cut in half for every 27° F increase in temperature above
160 °F
86
A special type of pillow block sometimes used on belt conveyors is called a
Takeup
87
To find the takeout amount needed to calculate final clearance when installing a bearing, refer to the
Manufactures chart
88
Which type of lubricant increases the effectiveness of a labyrinth seal?
Grease
89
Bearing temperature is typically________to_________ °F higher than the temperature of the housing
15;25
90
The threads of an acme screw are
Squared off and thick
91
Ball bearing screws are designed to
Move loads vertically and horizontally
92
The screw in a ball bearing screw is supported by
Standard ball bearings
93
In a contact seal, what forms the actual seal?
A thin film of oil
94
Before you install a lip seal, chamfer the end of the shaft and the leading edge of the housing bore at an angle of_______to______degrees.
15;30
95
The rolling contact of a ball bearing screw is_______% efficient.
90
96
Which of the following carries the load moved by a ball bearing screw?
Ways
97
When preparing a ball bearing screw for installation, use a_______ to expand the inner ring Og the bearings.
Hot-oil bath
98
Which seal is most effective when large quantities of contaminants are present close to the machinery?
V-ring
99
Which seal material works well for machines operating at extremely low temperatures?
Silicone
100
When using the grub screw method to hold a bearing in a pillow block, use
No collar
101
In planning a major overhaul of a hydroelectric unit, one of the best sources of information is.
Maintenance records
102
Determining the condition of the equipment should be done by performing a thorough inspection of the unit
6-12 months before the planned overhaul
103
A list of________ for all of the machine's components should be made from the drawing information
Weights
104
If substantial welding is needed, then a_______for the required repairs should be
written and distributed to all personnel that will be involved in the welding.
Welding procedure
105
Units with replaceable seal rings should have a________onsite
Spare set
106
Shaft run-out readings, bearing temperatures, pressures and Permanent magnet generator (PMG) voltage are all part of
Pre-shutdown readings
107
Pre-teardown readings include.
Shaft alignment readings, guide bearing clearance, seal ring clearance, and generator air gap
108
To make sure parts are installed in exactly the same position from which they are removed, they should be ________prior to removal
Match marked
109
The rigging to lift the thrust block should include (a) _______ so that the block can be kept level to prevent binding when it is lifted off the shaft.
Turnbuckles
110
After removing thrust and guide bearings, minor scratches and even some deep gouges can be adequately repaired by________
the high spots from the babbitt surface.
Scraping
111
In most cases, the repair of_________
damage can be accomplished much more effectively with the runner removed from the turbine pit, as the runner can be positioned for easier access.
Cavitation
112
Operational readings should be taken once the unit has been determined to operate with no problems, they include:
Bearing heat run, shaft run-out readings, load rejection tests
113
To prevent the damage that could occur from circulating currents passing through them the following are insulated from the frame and should be checked with an ohmmeter prior to startup:
Upper guide bearing, thrust bearing,pmg
114
A very thorough inspection of the________ __________ and the _________ _________ should be made to check for any bolts, nuts, tools, etc.
Generator housing; spiral case
115
There should be________ leakage upon the initial startup after the installation of new turbine shaft packing. The packing gland should be________ evenly and in small steps until the leakage is reduced sufficiently.
Generous; tightened
116
When setting clearances on upper and lower guide segmented shoe bearings, install a feeler gage to check clearance by
inserting the feeler gauge so that it extends all the way through the
bearing
117
When working on wicket gate adjustment, the amount the servomotor travels after the gates contact each other is referred to as the________.
Squeeze
118
When aligning a unit, it is important to make the bearing centers all_________
the shaft must be perfectly plumb. This can be accomplished by installing the turbine bearing and shimming the shaft to center in the_______bearing(s).
Concentric; turbine
119
A more accurate method of measuring the preload of a coupling bolt is to measure the amount the bolt ________ as the nut is tightened.
Stretches
120
When doweled components are moved during the alignment process following the overhaul of a unit,________
is necessary
Re-doweling
121
Dowels have a very________ fit to prevent the components from shifting once the part is positioned.
Tight
122
To find the unit's center, the upper bridge and head cover should be installed after all the _______ parts have been removed. A ________ wire should be hung through the unit and reference measurements taken from the stator, the turbine bearing housing, the packing box bore, and to trammel points in the draft tube
Rotating, single
123
Bearing cooling coils should be thoroughly inspected and ________ tested
Hydrostatically
124
The interior bore of the packing box can be built up with ________, as long as the box is structurally sound
Epoxy coating
125
Where an overlay of a dissimilar material is being used, such as stainless steel over mild steel, enough material should be removed to allow at least_______
weld passes to be made.
Three
126
The machine operator frequenty can give the troubleshooter
Valuable information
127
Mechanical, hydraulic and pneumatic systems all are worked on by the
Mechanical troubleshooter
128
The purpose of good maintenance is to
Keep machines and equipment working
129
Amantenance specialist reports to craft supervisors in all plant departments in a plan organized under
Central organization
130
In a large plant, the building-mantenance groups is most likely to be made up of.
Electricians, mechanics, plumbers, carpenters, and painters
131
All communication is essentially a cycle of ________ step(s).
Four
132
When you give a person a chance to express himself, you may
Find him easier to work with
133
Writing down an order
Helps prevent misunderstandings
134
Before you make a repair, you should
Find out what your responsibilities are
135
if you have a problem or complaint about your job, you should
Report it directly to your supervisor
136
If possible, you should schedule repair work for a time when
The machine is not in use
137
Before you can diagnose problems, you should
Be able to recognize normal operations
138
An ohmmeter measures
Resistance
139
Air supplies should be checked
When the machine is running
140
Your first duty in an emergency is
To protect workers from injury
141
Wen should the troubleshooter check the machine drawings in the service manual
Before working on the machine
142
Parts lists do NOT
Include a great deal of written technical information
143
High values of resistance can be measured with a(n)
Megohmmeter
144
A bourbon tube is used to measure
Pressure
145
Which of the following instuments measures the difference between two temperatures?
Thermocouple
146
The tools in you toolbox do NOT need to be
New
147
when should you remove your lock from the machine controls?
After you have replaced the machine guards and covers
148
To recheck a system after making a repair, you should
Run the system under both automatic and manual controls
149
Drive chains that run at speeds of over 500 feet per minute require
Constant lubrication
150
Which of the following conditions indicates conveyer overload?
Uneven spaces between the top plates of the conveyor chain
151
The diagram that shows both the external shape and he internal working parts of a system or a component is a(n)
Cutaway diagram
152
A piping system is shown in three dimensions in a(n)
Isometric diagram
153
A wiring diagrahm shows the
Physical relationships of devices in an electical system
154
Which of the following is used to trace the wiring in the celings and walls of a building?
Lighting diagram
155
Step by step instructions for testing equipment are induded in a(n)
Troubleshooting chart
156
Modern precision-built bearings
Help support power-transmission shafts
157
Side to side movement of a w in a sleeve bearing should be no more Than
Two thousands of an inch
158
Not all centrifugal compressors have
More than one air supply
159
Centrifugal, wet and bag are types of
Mechanical dust collectors
160
Electrical switchgear consists of
Equipment that controls, protects, and regulates machinery
161
A panelboard is a small assembly that contains
Either fuses or circuit breakers
162
Which type of diagram shows the parts of a circuit as they actually appear to the eye?
Pictorial
163
Potential difference is measured with a(n)
Voltmeter
164
In a normal work -order procedure, which of the following jobs is done by the scheduler?
Issues the work order
165
Determine what parts and supplies are needed to make an emergency repairs is the job of the
Emergency crew
166
The best approach for identifying the cause of a breakdown in automatic machinery is
The systematic one
167
The decision to run a machine part to the point of breakdown must be made
Very carefully
168
Wear to machine parts caused by contact with chemically active materials is an example of.
Corrosion
169
The inspection and repair of plant equipment at regular intervals is called
Planned maintenance
170
Which of the following machine parts require daily lubrication?
Shaft and bearings
171
The work order form is used for
Issuing instructions and obtaining feedback
172
All of the following will cause a drive belt to deteriorate EXCEPT
Too much ventilation
173
The sag in a drive chain should be about 1/4 in. for every_______ in of distance between the sprocket centers
12
174
The basic unit for measuring electric current is the
Ampere
175
Synthetic coatings greatly improve the strength and resistance of a
Floor
176
'You can control chain tension in a chain drive by changing shart centers or using a(n)_________sprocket
Idler
177
A roller chain should be allowed to sag________ percent of the distance Between sprocket centers
About 2
178
in chain operations, the areas of greatest load are the
Chain joints
179
You should make your first full-scale inspection of a new drie chain after_______hours of operation
24
180
chain side plates that show signs of uneven wear usually indicate that the
Drive is misaligned
181
In a vertical chain drive without an idler, the shafts should be installed at an angle of no more than
60 degrees
182
The most common cause of drive chain failure Is.
Improper lubrication
183
Which of the following describes the Type lll lubrication method?
Splash
184
A scraping or slapping noise during a test run of a chain drive may indicate that
The chain is striking something
185
Before using chain that has been stored on open reel, you should
Clean it with solvent
186
After mounting sheaves and pulleys, you should check their alignment with a
Straightedge
187
The best way to tighten a v-belt that has stratched is to
Adjust the distance between sheaves
188
A splice commonly used on low-speed flat belts is the ________ Splice
Stepped
189
If a new flat belt is running well, how long should you test run it under normal load?
48 hours
190
A burned spot on a belt probably indicates that
The belt is overloaded
191
Which type of belt is installed on sheaves rather than on pulleys?
V-belt
192
If a v-belt in a multi-belt drive shows wear, you should
Replace the full set of belts
193
Which of the following is the correct way to check a V-bell's tension?
Apply a specific amount of force to the top side of the belt
194
Which of the following is the best way to take up slack in a flat belt?
Adjust the center distance
195
The pulleys for a positive-drive belt have a(n)
Flange on each side
196
Which of the following drives permits practically no misalignment of the shafts?
Gear
197
The critical dimension that ensures accurate meshing of a worm and worm gear is its
Distance between the centers
198
When mounting spur or helical gears that have only one hub, you should position the hub
Away from the bearing
199
When cracked or broken areas appear on gear teeth that are almost new, the cause is probably (a)
Foreign object
200
If the metal at the tips and roots of gear teeth has been gouged or worn, the cause is probably (a)
Too tight a fit between gears
201
The OP of a gear is the ratio of the number of teeth to the_______, in inches
Pitch diameter
202
Which of the following is used to check gear alinement after instatation?
Steel square
203
What should you do if spalling occurs in an open gear driver?
Heart treat the teeth
204
Which of the following is the best solution for gearing with cracked rims?
Replace the gear
205
When installing an enclosed gear drive on the floor, you should mount the feet on (the) (a)
Steel base pads
206
What component of an enclosed gear drive prevents the buildup of pressure or the formation of a vacuum inside the drive housing?
Breather
207
If an enclosed gear drive is to be stored in the plant for a long time, you should
Fill the drive completely with oil
208
Most unusual noises that develop after an enclosed gear drive has run a while originate in the
Shaft bearings
209
what does discoloration of warm gear tecth indicate?
Burning caused by overloading
210
Which fool is used to check the leveiness of an enclosed gear drive on its foundation?
Spirit level
211
Which is the most common method of lubrication for bearings on enclosed gear drives?
Splash
212
During the run in period, you should run the drive system at half load for ________ hr
8 to 10
213
After a gear drive's first week of operation under full load, you should
Check the oil level
214
Which of the following is found on the nameplate of an enclosed gear drive?
Load capacity
215
Which elements of a drive package should you move to set the coupling gap?
Motor
216
What instrument is used when very precise coupling alignments must be made?
Dial indicator
217
The only kind of couplings that require lubrication are those that have
Metal-to-metal contact
218
A floating shaft coupling should be used when the
Drives exert axial thrust
219
If the power requirements of a driven machine have been changed so that overloading occurs, you can solve the problem by installing (the) (a)
Next-larger coupling
220
A coupling can serve all of the following purposes except
Insulate against high temperatures
221
The gap betwoen a spacer coupling and the hubs should be_________in
0
222
What is the usual cause of whipping on a floating shaft?
Excessive misalignment
223
An uneven wear paller on a gear-type coupling is usually a sign of
Misalignment
224
The slack in the fit between coupling components is known as
Backlash
225
Which of the following happens to open gearing during the run in period?
Gears polish up
226
The most common cause of failure in law clutches is
Jaw breakage
227
-belt sheaves, shafts, and gears can all be used as
Takeoff members
228
Localized wear on clutch friction surfaces often indicates
Misalignment
229
Frequent slippage of a brake or clutch is usually an indication of
Overloading
230
Chatter is usually caused by
Loose or faulty actuating devices
231
Friction clutches use one or more discs to
Transmit torque to the load
232
Rapid wear between the friction surfaces in an electric brake or clutch is caused by
Overheating
233
When the slip speed of a clutch drops to zero, the maximum torque the clutch can exert
Increases
234
The capacity of a clutch to dissipate heat depends on its size and
Armature speed
235
If a brake or clutch fails to engage properly. the first thing to check is the
The voltage supple to the field coil
236
At_________ output speed, the flanges on the input shaft of an adjustable speed drive are ________
Maximize; closest together
237
The best protection against unwanted heat in an enclosed drive is a(n)
Steel baffle
238
When test-running an adjustable-speed drive under no-load conditions, it is necessary to operate the drive
Through it’s full speed range
239
If you find ridges in a drive's sheave flanges on an adjustable speed drive, you should
Sand or polish the edges right away
240
In an enclosed drive, high temperatures usually result from (a)
Overloading the shaft bearings
241
The amount of slip between a turbine and its impeller is normally a difference of__________to_________percent at full load
3 to 5
242
A condition called a "stall load" can oour in a fluid coupling when the impeller ________ and the turbine __________
Rotates; does not rotate
243
Overheating in a fluid coupling is usually caused by
Too much slip
244
A polyphase torque converter has _________ stator(s) that_________
Two or more; rotate
245
Alf you find seals that are hard and cracked when you are inspecting a coupling, you should
Replace them
246
An enclosed gear drive's thermal capacily is usually expressed in
Horsepower
247
When you need to change the speed of a load shaft you should select a drive with (a) (an)
Adjustable-speed belt
248
The major cause of drive failure is
Improper lubrication
249
If an overload occurs in a drive system that is equipped with a spring-operated overload device the
Sprocket will slip
250
When test running a drive prior to placing it in service, you should run the drive under no-load conditions for
20 to 30 minutes
251
The two units of measuring liquid pressure are
psi and ft of head
252
The available NPSH of a system should be ________ the required NPSH of the pump
Equal to or greater than
253
The formation of vapor pockets, or bubbles, within a liquid is called
Cavitation
254
The horsepower requited to achually dive a fud handing pump is called the________ hp
Brake
255
One electrical horsepower equals ________ watts
746
256
The area that surrounds and houses the packing in a pump is called the
Stuffing box
257
When installing four or more packing rings, you should stagger the joints _________ degrees apart
90
258
The most common mechanical seal configuration is the_________ seal
Single internal
259
In some mechanical seals, the rotating element is secured to the shaft by a
Boot
260
The major cause of burned seals is
Improper lubrication
261
After grouting a baseplate, you should allow the grouting mixture to set for at least
48hr
262
When removing springs from pump feet, you should measure movement with a
Dial indicator
263
Unwanted movement of a pump shaft along its axis is called
End play
264
Cavitation is caused by
Pressure loss
265
Loss of clearance between wearing rings is called
Ring seizure
266
On a pump that has both bearings on the same side of the impeller, the bearing nearest the impeller is called the
Inboard
267
The most common sign of cavitation in a pump impeller is
Pitting on the back side of the vanes
268
In general, runout on a shalt should not exceed _________in
0.003
269
Too much clearance between the stationary rings and the impeller or rotating rings of a centrifugal pump will cause
Fluid leakage
270
When installing a new gasket, you may wish to apply ________ to the lower half of the casing
Shellac
271
The most commonly used type of all rotary pumps is the_______ pump
External gear
272
The riser used to vent a system at the discharge side of the pump should be about _________ umes as long as the diameter of the pipe.
5
273
in a vane-type rotary pump, what keeps the sliding vanes in contact with the pump housing?
Centrifugal force
274
imlemal bearings on rotary pumps are most often lubricated by
The fluid being pumped
275
If a rotary pump is not delivering fluid at its discharge side, the first thing you should do is
Stop the pump
276
Which method is used to measure a pipe with a fitting at one end?
End-to-center
277
Which of the following displayed symbols describes a flanged tee?
278
What type of flange is used to seal the end of a pipe?
Blind
279
Given the drawing and information below, calculate the face-to-face distance between the fittings
5ft 4in
280
Straight internal pipe threads in pipe couplings are represented by the code letters
NPSC
281
In complete pipe specifications, code letters are preceded by two numbers which indicate the
Nominal pipe size and number of threads/in
282
The distance from a given point on one pipe thread to the same point on the next thread, measured parallel to the pipe centerline, is called the
Pitch
283
You need to replace a threaded pipe between 45° elbows in a straight offset. The set is 5 ft, and the travel is 7 0 ft. The center-to-face dimension of each 45° elbow is 2 in, and the pipe's thread length is 75 in. The total end-to-end length of the replacement pipe is
82.34in
284
Ratchet threaders can be used on pipe up to about ________ in. in diameter.
6
285
Socket-welding fittings are used for joining pipe of what diameters?
4in or less
286
Backing rings should always be made of
Material compatible with the pipe material
287
Squareness is a term indicating that a pipe forms a _______ angle with another
90° 
288
The major assembly consideration when fabricating flanged connections for a rolling offset is
Aligning the holes
289
The usual gap between pieces of pipe to be butt-welded is approximately
3/16 in
290
A major advantage of thermoplastic pipe is that
It is highly resistant to corrosion
291
Which of the following is a fiberglass-reinforced thermosetting pipe material?
RTRP
292
The solvent cement used to install fittings on thermoplastic pipe requires cure completely
1/2-4
293
When installing threaded fittings on plastic pipe, you should tighten the joint by hand or with a
Strap wrench
294
To ensure a good bond when installing bell fittings on thermosetting pipe, the ends of the pipes should be
Lightly sanded
295
What kind of hanger is used when a rigid hanger would swing more than 4 degrees?
Roller
296
A steam trap is a pipefitting accessory that removes
Condensate
297
Steam traps should be installed at the_______ point in the system
Lowest
298
Which of the following fixtures is used to remove very small particles from a piping system?
Filter
299
What kinds of expansion joints can be used where temperature changes cause axial pipe movements?
Slip and bellows joints
300
Given a 45° straight offset, with a 41-in travel, a center-to-face elbow dimension of 2-in. and a 3/4 in. thread length, what is the end-to-end pipe length?
38.5in
301
Water is usually carried in ________ tubing, if it is under high pressure, _________ tubing is usually used
Copper ; stainless steel
302
A flareless compression fitting is one that
Bites into the tubing
303
Annealing is sometimes necessary to make tubing
Easier to bend
304
When you use a cutter to cut tubing, the cutter should ________ and the tubing should _________
Rotate; not rotate
305
To get the most accurate measurement of required tubing length, you must measure along the tube's
Centerline
306
Tensile strength of tubing is based on the ________ and the ________
Tubing material; wall thickness
307
How does increasing the operating temperature affect the strength of tubing?
Decrease it
308
What type of fitting is commonly used on tubing that carries a flammable liquid or gas?
Flared
309
What is the first step in installing a flared fitting?
Slide the nut over the tube
310
What is the most common cause of leaks in a tubing system?
Poor fitting connection
311
What is the most frequently used hydraulic fluid?
Oil
312
What device is commonly used to keep hydraulic systems from building up excess pressure?
Relief valve
313
What type of fittings should be used with copper tubing in hydraulic systems?
Brass
314
If the pump in a hydraulic system is noisy, the most likely cause is a(n)
Insufficient fluid supply
315
Contaminated fluid in a hydraulic system often causes
Fluctuating pressure
316
A typical multipurpose industrial hose can carry saturated steam at pressures of up to
150 psi
317
A shaft that serves to support a fitting during assembly is called a
Mandrel
318
The most common method of attaching reusable fittings to hose is
Threading
319
Calculate the required hose length if a 40° bend is to be made in a hose and the radius of the bend is 8 in.
5.58in
320
Hydrostatic tests of a hose system should be conducted at _________ percent of the recommended working pressure of the hose.
150
321
The most important dimension of a gasket, from a total performance standpoint, is its
Thickness
322
The electrical signal generated by a profilometer is converted into a reading displayed in
rms
323
Waviness in flange surfaces is usually expressed in ________ of an inch
Thousands
324
Coatings serve to reinforce a joint seal and to keep the gasket from
Creeping
325
TFE-based gasket strips can accommodate operating temperatures of up to
250°F 
326
Which of the following valve materials is the best choice for service conditions that include high pressures, high temperatures, and a corrosive fluid?
Stainless steel
327
If a valve must be removed frequently for service or repair, the valve-to-pipe connection should be
Threaded
328
If the stem of a globe valve does not move freely, one likely cause is a
Damaged spot on the thread
329
What is usually the first indication of a valve problem?
Leakage
330
The first part of a diaphragm valve to wear out is usually the
Diaphragm
331
What causes a pop safety valve to open?
Pressure rising above a preset level
332
For most pop safety valves, pressure and temperature conditions are usually limited to
250 psi and 450°F
333
Chatter in pop safety valves is caused by a________ volume of flow at a ________ pressure
Low; high
334
What part of a safety relief valve contains the pressure that opens the valve?
A huddling chamber
335
A mechanism used to open or close a valve is called a(n)
Actuator
336
The maximum air pressure for pneumatic diaphragm actuators is approximately
125 psig
337
Which of the following devices is used to measure fluid pressure?
Bourbon tube gauge
338
Which of the following indicates flow rate by producing an electrical signal?
Turbine flowmeter
339
Accumulators are used for
Storing pressure
340
Applications that call for fully opened or fully closed positions are best handled by a ________ valve
Gate
341
The valve best suited for regulating flow is the _________ valve
Angle
342
Which of the following valve materials is most likely to be used in high-pressure, high-temperature conditions?
Steel
343
The marking "WOG" on the body of a valve stands for
Cold water, oil, and gas
344
Flanged joints require the use of _______ to create an effective seal
Gaskets
345
One of the most common signs of insulation failure in steam lines is
Leakage
346
Condensate in a steam tracing system should be drained to the
Collection header
347
One of the disadvantages of electric tracers is that they
Require constant monitoring
348
The simplest and surest way to protect an exposed water line from freezing is to
Drain the line
349
Which of the following is an example of passive corrosion protection?
Installing a pipe liner
350
The first step in stopping leakage around the stuffing box of a gate valve is to
Tighten the gland bolt nuts
