DDE General Sub/Safety/HVAC Flashcards
1
Q
The purpose of annealing any metal is to make the metal __________.
A
softer
2
Q
Reheating a hardened component to a temperature LOWER than the hardening temperature and then cooling it is known as __________.
A
tempering
3
Q
To anneal a copper gasket, you should heat the gasket __________.
A
cherry red and quench in water
4
Q
When a metal is undergoing heat treatment for the purposes of annealing, besides refining the grain structure, what is the determining characteristic of the metal?
A
Softened condition
5
Q
Copper sheet metal that is to be used as a gasket, is usually annealed by heating it to a cherry red color, and then __________.
A
dousing it in cold water
6
Q
Tubing is sized by __________.
A
nominal outside diameter
7
Q
After adding grease to a ball bearing with a handheld grease gun, you should __________.
A
run the machine with the bearing housing drain plug open for a short while
8
Q
What material is most commonly used as a sacrificial anode for the purposes of minimizing the galvanic corrosion of steel and cast iron?
A
Zinc
9
Q
If water continues to flow excessively from the device shown in the illustration, the problem is most likely due to __________. GS-0155
A
item “H” being fouled or plugged
10
Q
The diaphragm orifice labeled “H”, as shown in the illustration is used as a/an __________. GS-0155
A
time delay
11
Q
The device shown in the illustration is a __________. GS-0155
A
flushometer valve (Sloan valve)
12
Q
The pressure applied to the instruments via port “A”, as shown in the illustration, is 16 psia. What will be the equivalent pressure readings for “B” and “D”? GS-0154
A
B = 1.3 psig D = 36 inches of H2O
16 psia - atmospheric pressure of 14.7 = 1.3 psig
1.3 psig / .036 pounds H20 per in. = 36 in. H20
36 in. H20 / 13.5 pounds Hg. per in. = 2.7 in. Hg.
13
Q
How often should the air receivers on a compressed air system be drained of moisture and emulsions?
A
Daily
14
Q
The barge shown in the illustration is 40’ X 20’ X 10’ (12.192 m X 6.096 m X 3.048 m ) and weighs 22.9 long tons (23.28 t) when empty. It has been loaded to a draft of 5 feet (1.524 m) in salt water. How many long tons of cargo have been added? GS-0157
A
91.4 long tons (92.91 t)
Displacement when loaded = 40 x 20 x 5 = 4000 cu. ft.
4000 / 35 cu. ft. = 114.3 LT of total weight
114.3 LT total weight - tare weight of 22.9 = 91.4 LT added
15
Q
The heat required to change a substance from a solid to a liquid while at its freezing temperature, is known as the latent heat of __________ .
A
fusion
16
Q
The heat identified by only a change in temperature is known as __________.
A
Sensible heat
17
Q
A tailstock ‘dead center’ has been given that name because it __________.
A
does not revolve
18
Q
The drains of lavatory sinks are fitted with P-type or S-type traps to __________.
A
provide a seal against sewer gas rising into the compartment
19
Q
If the orifice in the loop seal of a flash evaporator were to become significantly enlarged through erosion, the __________.
A
evaporator absolute pressure could eventually equalize in both stages to that of the second
stage
20
Q
Work that cannot readily be mounted between lathe centers is usually held in a __________.
A
chuck
21
Q
The lathe tool shown as figure “T” in the illustration is commonly known as a/an __________. GS-0090
A
right-cut roughing tool
22
Q
The lathe tool shown as “Q” in the illustration is a __________. GS-0090
A
left hand side facing tool
23
Q
The main difference between a common lathe dog and a safety lathe dog is that the latter __________.
A
has a headless set screw
24
Q
The lathe tool shown as figure “U” in the illustration is commonly known as a/an __________. GS-0090
A
cutting-off tool
25
Before welding repairs are performed to repair a crack, what is the correct procedure for performing an emergency crack stopper?
A 3/8-inch hole should be drilled at each end of the crack, making sure that none of the crack extends beyond the two holes.
26
Who is in charge during bunkering?
PIC, usually the chief
27
The minimum firefighting equipment to be maintained onboard a tank vessel, can be determined from the __________.
vessel's Certificate of Inspection
28
A characteristic of lubricating oil which causes additional centrifuging requirements for proper purification is __________.
low oil demulsibility
29
demulsibility of a lube oil is defined as __________ .
the ability of oil to separate from water
30
The ability of an oil to separate cleanly from an oil and water mixture is referred to as its __________ .
demulsibility
31
A ball bearing will overheat if __________.
completely packed full of grease
32
Which of the listed types of files is the best for producing a fine finish on metal?
Mill
33
During oil transfer operations, who would be responsible to guarantee that the posted transfer procedures are being followed?
The designated person in charge
34
Which one of the following is a difference between a typical relief valve and a typical safety valve?
A relief valve gradually opens as pressure increases above set point pressure whereas a safety valve fully opens at the set point pressure.
35
As it pertains to safety valves, what is the definition of blow down?
Blow down is the difference between the valve popping pressure and the valve reseating pressure.
36
Safety valves are designed to open _____ when lifted by excessive pressure and only reseat when the pressure has __________.
wide,
| dropped significantly
37
How would the pressure setting of the illustrated self-contained, internal-pilot, piston- operated steam pressure-reducer be reduced to a lower set point? (GS-0044)
The adjusting spring would need to have its compression load reduced by rotating the adjusting screw counter-clockwise further out of the adjusting spring chamber.
38
Suppose the illustrated self-contained, internal-pilot, piston-operated steam pressure- reducing valve is part of a 600-150 psig reducing station. If there was an increase in demand for steam downstream, what statement correctly represents how the valve would initially respond? (GS- 0044)
The downstream pressure would drop, causing the control diaphragm to flex downward and further open the pilot valve.
39
To properly remove packing from a valve stuffing box, you should use a __________.
packing puller (or packing hook)
40
The basic function of the centrifugal pump impeller is to __________.
directly increase the velocity of the liquid being pumped
41
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by __________.
cavitation
42
When reviewing log books, the main salt water cooling pump discharge pressure has decreased in the three years since overhaul. What is likely to be the cause of the problem?
Increased impeller and wear ring clearance
43
A distinguishing feature of an eductor, when compared to other pumps, is the __________.
lack of moving parts
44
Zincs are installed in the main and auxiliary condenser water boxes to __________.
reduce the effects of electrolysis
45
When hardened metal is heat-treated by a process known as tempering, what metallurgical properties are achieved?
decrease in brittleness
46
What is the benefit of using water fog in firefighting?
Fog absorbs a lot of heat due to it's greater surface area.
47
Pump pressure can also be expressed as _______.
feet of head
48
A pressure reading of 00.0 psig is theoretically equal to __________.
14.7 psia
49
What term is defined as the amount of heat required to convert a unit mass of a substance from a liquid to a vapor at constant temperature and pressure?
Latent heat of vaporization
50
In the illustration, line "C" is a __________. GS-0006
dimension line
51
In the illustration, line "D" is a/an __________. GS-0006
hidden line
52
In the illustration, line "J" is used to depict a _________? GS-0006
cutting plane line
53
Figure "B", shown in the illustration, is dimensioned to indicate a/an __________. GS-0019
interference fit
54
As shown in the illustration, if figure "21" indicates the "TOP VIEW" of an orthographic projection, and figure "11" indicates the "FRONT VIEW", which figure would best represent the correct "RIGHT SIDE VIEW"? GS-0165
Figure "10"
55
How many hidden lines are shown in the right side (end) view of the drawing illustrated? GS-0021
None
56
Of the views labeled "1", "2", "3", and "4", select the one that correctly represents the right side view of the unnumbered object in the illustration. GS-0003
4
57
The reading on the vernier caliper scale shown in figure "G" in the illustration is __________. GS-0082
2.368 inches
58
For greater accuracy, some micrometers have a vernier scale making it possible to read in increments of __________.
ten thousands of an inch
59
To determine the diameter of a small hole, which of the listed tools must be used with inside calipers to get an accurate reading?
Micrometer
60
Enlarging one tube end so the end of another tube of the same size will fit inside is termed __________.
swaging
61
The tool shown in the illustration is called a __________. GS-0072
Center gage
62
In machine shop practice, a center gage is used for checking the angle of __________.
60° thread cutting tools
63
A gate valve installed in a piping system should be used __________.
in either fully closed or fully opened positions
64
Lantern rings are provided on centrifugal pumps to __________.
provide a passage for the stuffing box sealing liquid
65
Specific gravity of mercury =
13.56
66
The device shown in the illustration is commonly known as a/an __________. GS- 0071
mechanical seal
67
An increase in rotor clearances in a rotary pump will __________.
decrease pump capacity
68
What causes cavitation in a centrifugal pump?
Vapor pockets in the flow stream
69
One of the consequences in continuing to operate a centrifugal pump with the discharge valve closed, is that the __________.
pump will overheat
70
The simplest method to use for determining if a centrifugal pump is operating as designed, is to __________.
close off the discharge valve, and watch for a rise in pressure
71
A centrifugal pump may fail to deliver water when first started if the __________.
pump is not primed
72
Why is the discharge pressure of a herringbone gear pump steadier than the discharge pressure of a simple spur gear pump?
One discharge phase begins before the previous discharge phase has been completed.
73
A fully charged standard SCBA can be expected to supply air under non-stressful conditions for approximately __________.
30 minutes
74
In pressure measurement, absolute pressure is defined as the difference in pressure between __________ .
a perfect vacuum and the total pressure at a given point
75
If one drive belt on an air compressor is found to be worn you should __________.
replace all of the belts
76
When removing roller bearings from a shaft, the force of the puller should be applied to the bearing __________.
inner race
77
Why do roller bearings have higher loading capacities than ball bearings?
They have a greater contact area.
78
What mode of heat transfer is associated with the transport of thermal energy from one location to another by fluid in motion?
Convection
79
What mode of heat transfer is associated with the transport of thermal energy within a body or between two bodies in direct contact?
Conduction
80
What mode of heat transfer is associated with the transport of thermal energy through a transparent medium by means of electro-magnetic energy in the infrared spectrum?
Radiation
81
In order to take suction on the lube oil drain tank cofferdam with the bilge pump shown in the illustration, how many suction side valves must be open? GS-0042
Two
82
If the operator releases the handle of the illustrated device while the system output is in motion, the valve will __________. GS-0032
return to its centered position and the output speed will drop to zero
(called a spring centered directional control valve)
83
Regarding the device shown in the illustration, if the operator releases the handle while the system output is in motion, the __________ . GS-0035
valve will remain in position with the output remaining unchanged
(called a three-position, detented, directional control valve)
84
The illustrated valve is known as a __________. GS-0056
swing check valve
85
An arrow superimposed on a hydraulic graphic symbol at approximately 45°, as shown in the illustrated figures A, B, and C, indicates the component __________. GS-0068
can be adjusted or varied
86
The hydraulic graphic symbol illustrated as Fig. C is used to depict a/an __________ . GS-0068
variable output, single direction flow pump
87
The hydraulic graphic symbol illustrated in Fig. B is used to represent a/an __________ . GS-0068
variable orifice
88
Which of the devices shown in the illustration is designed for both inside and outside measurements? GS-0073
C
89
The general purpose of a heat exchanger is to __________.
heat, or cool one fluid by means of another fluid
90
Pressure in an operating hydraulic system is developed __________.
by resistance to the fluid flow through the system
91
Energy imparted to the hydraulic fluid in an operating hydraulic system is stored in the __________.
accumulator
92
How many BTUs must be added to one pound of water at 32°F to raise the temperature to 212°F?
180 BTUs
93
If your ship burns 8 tons of fuel per hour at 15 knots, how many tons per hour will it burn at 19 knots?
16.3 tons
```
CR2/CR1 = (Sp2 / Sp1)^3
CR2/8T = (19kt/15kt)^3
CR2 = (19/15)^3 x 8T
```
94
Your ship has steamed 1786 miles at 17 knots using 515 tons of fuel oil. The distance remaining to your next port is 1922 miles. If you increase speed to 20 knots, how much fuel will be used to reach that port?
767 tons
Cons2/Cons 1 = (Sp2/Sp1)^2 x Dist2/Dist1
Cons2/515T = (20kt/17kt)^2 x 1922mi/1786mi
Cons2/515T = 1.38 x 1.08
Cons2 = 1.38 x 1.08 x 515T
95
If the temperature in a hot air manifold were found to be 122°F, what will be the equivalent reading on the centigrade scale?
50°C
(°F - 32) x 5/9
(122 - 32) x 0.56
90 x 0.56
96
One cubic foot of salt water would equal approximately how many pounds?
64
97
Bronze metal is an alloy composed mainly of __________.
copper and tin
98
Brass metal is an alloy composed mainly of __________.
copper and zinc
99
A 'close nipple' is a piece of pipe that is __________.
threaded along the entire length
100
The size of ball and roller bearings can be identified by the __________.
manufacturer's numerical code
101
If you have a duplex, single acting, reciprocating pump making 140 strokes/minute with a 3" diameter cylinder, and a 12" stroke with a 94% volumetric efficiency, what is the capacity of this pump?
48 gpm
```
[area x length of stroke x # of effective strokes x efficiency] / 231
area = 7.07 cu. in.
length = 12 in.
effective strokes = 140
efficiency = 0.94
```
102
The best method of fixing a winch motor bearing of the sealed type that is running hot is to __________.
replace the bearing with a new one
103
Which of the following terms is used to identify the pressure of a liquid entering a centrifugal pump?
Suction head
104
What is the operating principle of centrifugal pumps?
A flow is developed by imparting kinetic energy to the fluid by the rotation of an impeller.
105
The static suction lift of a pump is the difference in elevation between the __________.
centerline of the pump and the level of the liquid in the suction well when the source of liquid is below the pump
106
The purpose of wearing rings as found in large centrifugal pumps is to __________.
permit internal components that are subjected to high erosion conditions, to be replaceable thereby extending the service life of the pump
107
How is a vacuum is created by a jet pump or an eductor?
A rapidly moving stream of fluid passing through a nozzle.
108
An advantage of a helical gear pump over a simple gear pump is that the helical gear pump is capable of __________.
producing a smoother discharge flow
109
Reduced capacity, accompanied by vibration and noise at the suction of a centrifugal pump is a result of __________.
cavitation
110
If the capacity of a centrifugal pump decreases gradually over a long period of time, you should replace the __________.
wearing rings
111
An air compressor is equipped with an intercooler and an aftercooler to __________.
increase compressor efficiency and economy
112
The unloading system on an air compressor will __________.
allow the motor to turn the compressor opposed only by friction
113
Air compressor cylinder unloaders enable the compressor to __________.
start and come up to speed before air compression begins
114
Item "E" shown in the illustration is used in the hydraulic circuit as __________. GS- 0103
the manually operated pump located in a common passage way to close the water tight door in an emergency
115
Item "B" shown in the illustrated hydraulic circuit is used to __________. GS-0103
shut down the remotely operated electric motor driven pump when the watertight door has closed
116
The counterbalance valve (5) in the winch circuit shown in the illustration ________. GS-0161
helps prevent slung loads from dropping prematurely
117
If the operating pressure is determined to be normal in the system shown in the illustration, yet the crane does not swing (slew) in either direction when the directional control valve is operated, the problem could be ________. Illustration GS-0161
an obstruction in the brake release cylinder line (2)
118
In the steering gear system shown in the illustration, if the maximum working pressure is applied to the face of the ram, the total force on one piston will be __________ . GS-0104
209,230 lbs.
```
Force = Pressure x Area
Force = 1850psi x 113.097 in. sq.
```
119
```
The steering gear unit shown in the illustration, which of the conditions listed will occur as 'left rudder' is being obtained and only the 'No. 1' steering gear pump is running? GS-0104
A Cylinder end "H" is under pressure.
B Cylinder end "A" is relieving.
C Cylinder end "E" is under pressure.
D Cylinder end "F" is relieving.
```
A Cylinder end "H" is under pressure.
120
```
While responding to a right full rudder command from the amidships position, which of the cylinders illustrated will be fully pressurized on the face of the pistons? GS-0104
A "B"
B "C"
C "E"
D "A"
```
C "E"
121
In a hydraulic system using the device illustrated, the high pressure return is provided by __________. GS-0118
A
122
The hydraulic pump which would be mounted on the unit shown in the illustration, may begin to cavitate if __________. GS-0118
"D" is not kept clean
123
A hydraulic system flow-control circuit is shown in the illustration and is known as a __________. GS-0105
metered-in circuit
124
A hydraulic system flow-control circuit is shown in the illustration and is known as a __________. GS-0106
metered-out circuit
125
If solenoid "A" illustrated is energized, the __________. GS-0041
cylinder should extend
126
In the system illustrated, what reading should be indicated on the pressure gage, if the load (x) is 8000 lbs (3632 kg) and the piston area (y) is 10 sq. in (64.5 sq. cm)? GS-0062
800 psi (56.31 kg/cm2)
```
Pressure = Force / Area
Pressure = 8000 / 10
```
127
The illustrated device operates on the principle that the height of the liquid in gage "C" is __________ . GS-0066
proportional to the height of the liquid, H
128
The illustrated device is normally used to __________ . GS-0066
provide a remote reading of the liquid stored in the tank
129
The device shown in the illustration is used to determine the __________. GS-0069
A flash point of oil
B pour point of oil
C viscosity of oil
D lubricating qualities and film strength of oil
C viscosity of oil
130
The purpose of the instrument illustrated is to __________. GS-0079
measure wire diameter
131
Which characteristic of fuel oil establishes the danger point as far as transferring, pumping, and firing procedures are concerned?
Flash point
132
By definition, combustible liquids are liquids which __________.
have a flash point of 80 degrees F or higher
133
The lowest temperature at which fuel combustion becomes self-sustaining in the presence of a source of ignition, is defined as the __________ .
fire point
134
The minimum temperature required to ignite gas or vapor without a spark or flame being present is called __________.
autoignition temperature
135
Combustible gas indicators measure the presence of combustible gases as a percentage of the __________ .
lower explosive limit
136
What type of valve is shown in the illustration? GS-0047
Gate valve
137
Which of the following statements is true concerning the valve shown in the illustration. GS-0047
(a) The valve only requires one turn of the hand wheel to fully open.
(b) The valve seats cannot be replaced or repaired.
(c) The valve is normally used to throttle the flow of liquid.
(d) The valve is a non-rising stem design.
(d) The valve is a non-rising stem design.
138
Assuming valve "A" is correctly aligned in the no-flow position as shown with the system in operation, which of the following statements is true? GS-0049
A) The fixed delivery pump would be stopped automatically by a pressure switch.
B) Valve "B" would be open before valve "D".
C) Valve "C" would be closed.
D) Valve "D" would normally open before valve "B".
D) Valve "D" would normally open before valve "B".
139
Valve "D" indicated in the illustration is referred to as a/an __________. GS-0049
unloading valve
140
The wire rope drum used in the illustrated hydraulic crane circuit is prevented from accidentally paying out by __________. GS-0161
components labeled 4 and 5
141
The safety feature which assists the hydraulic crane circuit illustrated to maintain the required boom angle is a function of item __________. GS-0161
18
142
One function provided by a hydraulic accumulator is to __________.
(a) provide an area where air can separate from the oil
(b) provide an area to separate solid contaminants from the oil
(c) act as an oil and water separator
absorb shocks occurring in the system
(d) absorb shocks occurring in the system
(d) absorb shocks occurring in the system
143
A reservoir is used in a hydraulic system to __________.
(a) store fluid until required by the system
(b) provide a place for air to separate out of the fluid
(c) provide a place for contaminants to settle out
(d) all of the above
(d) all of the above
144
An orifice-check valve placed in a hydraulic system is used to __________.
restrict movement of hydraulic fluid in one direction, but allow free movement in the other direction
145
Most solenoid valves are actuated by __________.
an electromagnet
146
Which of the listed pressure control valves would be used to establish the maximum operating pressure of a hydraulic system?
a) Pressure-reducing valve
b) Unloading valve
c) Counterbalance valve
d) Pressure-relief valve
d) Pressure-relief valve
147
Which component in a hydraulic system is commonly used to prevent the stray movements of a vertical load until required?
a) Pressure reducing valve
b) Counterbalance valve
c) Unloading valve
d) Sequence valve
b) Counterbalance valve
148
The torque rating of a fluid power motor is expressed in __________.
inch-pounds at a given RPM
149
In a fixed displacement axial piston hydraulic motor, the speed is varied by __________.
controlling the input flow rate (gpm)
150
The delivery rate of a variable displacement axial-piston hydraulic pump is controlled by varying the position of the __________.
tilting box or swash plate
151
Where should you expect to find striking plates on liquid storage tanks?
On the bottom of a fuel or ballast tank under the sounding tube.
152
Under normal conditions, the rate of heat transfer in a feed water heater is most greatly affected by the __________ .
temperature differential between the steam and feed water
153
The component of the illustrated compression fitting, figure "C", used to seal and eliminate leaks between the tubing and the fitting is part __________. GS-0100
I (o-ring)
154
Hazardous conditions exist which may result in spontaneous combustion when __________.
oil soaked rags are stowed in the machine shop
155
Which of the following practices is considered to be safe for the handling and use of compressed gas cylinders?
(a) Using oxygen as a substitute for compressed air for pneumatic tools.
(b) Cracking the valve on a hydrogen cylinder to clear dust and dirt.
(c) The storage of the cylinders in a well ventilated compartment.
(d) Routinely greasing or lubricating the valves on oxygen cylinders.
(c) The storage of the cylinders in a well ventilated compartment.
156
Latent heat can be defined as the heat which must be added to a substance in order to change it from a __________.
a) solid to liquid
b) liquid to vapor
c) solid to vapor
d) all of the above
d) all of the above
157
The rate of heat transfer from a hot region to a cold region is affected most by the __________.
temperature difference between the regions
158
```
Which of the following is required to be included in the fireman's (emergency) outfit?
A Chemical protection face shield
B Approved work vest
C Self-contained breathing apparatus
D 5 cell approved flashlight
```
C Self-contained breathing apparatus
46 CFR 77.35-10
159
Pipe threads are cut with a taper to __________.
provide a leak proof fit
160
The flash point of a liquid refers to the temperature __________.
at which a liquid will give off inflammable vapors
161
The lowest temperature required to cause self-sustained combustion of a substance independent of any outside source of ignition is called __________.
ignition temperature
162
Which of the listed characteristics of lube oil are the most important to the engineer from an operational standpoint?
a) Ash content, carbon residue, and gravity
b) Viscosity, acidity, and demulsibility
c) Pour point, flash point, and precipitation number
d) Auto ignition point, viscosity index, and film strength
b) Viscosity, acidity, and demulsibility
163
Cubic inches in one gallon
231 cu. in. per gallon
164
Cubic feet of seawater per long ton
35 cu. ft. in one long ton
165
1" head of water = ____ psi
0.036 psi per 1 cu. in. of water
166
```
Stability is determined principally by the relationship of the center of gravity and the __________.
A keel
B center of buoyancy
C center of flotation
D aft perpendicular
```
B center of buoyancy
167
Steering Systems
In a closed-loop process control system, what term is used to describe the action of measuring the difference between the actual result and the desired result and using that difference to drive the actual result toward the desired result?
(a) Gain
(b) Feedback
(c) Instability
(d) Dead band
(b) Feedback
168
Steering Systems
In a closed-loop process control system, what statement concerning feedback is true as it relates to stability and the direction of error displacement?
(a) Negative feedback is used to minimize instability by pushing the system in the same direction as the error displacement.
(b) Positive feedback is used to minimize instability by pushing the system in the same direction as the error displacement.
(c) Negative feedback is used to minimize instability by pushing the system in the opposite direction as the error displacement.
(d) Positive feedback is used to minimize instability by pushing the system in the opposite direction as the error displacement.
(c) NEGATIVE feedback is used to minimize instability by pushing the system in the OPPOSITE direction as the error displacement.
169
Steering Systems
In a closed-loop process control system featuring negative feedback, what is the function of the error detector within the controller?
a) The error detector computes the sum of the measured value of the controlled variable and the desired value (set point).
(b) The error detector computes the quotient of the measured value of the controlled variable and the desired value (set point).
(c) The error detector computes the difference between the measured value of the controlled variable and the desired value (set point).
(d) The error detector computes the product of the measured value of the controlled variable and the desired value (set point).
(c) The error detector computes the DIFFERENCE between the measured value of the controlled variable and the desired value (set point).
170
The efficiency of a flash type evaporator can be increased by __________.
decreasing the absolute pressure of each stage
171
Which of the following descriptions best identifies the operating principal of a flash- type evaporator?
(a) Sea water is heated to boiling temperature while under a vacuum.
(b) Sea water is passed over heated plates in a thin film.
(c) Heated sea water is injected into a vacuum chamber.
(d) Sea water is forced through a heated eductor.
(c) Heated sea water is injected into a vacuum chamber.
172
Why would a flash type distilling unit be more efficient when operated in cooler seawater temperatures?
Evaporator vacuum is increased.
173
In a flash evaporator, heated water under pressure is converted into vapor by suddenly __________.
decreasing its pressure
174
Small droplets of water entrained in the flashed vapor produced in a flash-type evaporator are removed by the __________.
demisters
175
A vacuum is initially created in a flash type distilling plant by __________.
air ejectors, eductors, or a separate vacuum pump
176
Which of the following desalination plants will always require a sterilizer when providing water to a potable water system?
(a) Titanium plate type unit
(b) Multi-stage flash type unit
(c) Submerged tube type unit
(d) Reverse-osmosis type unit
(d) Reverse-osmosis type unit
177
What is the BEST indication that the membrane modules of a reverse-osmosis freshwater generator must be serviced by flushing or cleaning?
An excessive pressure drop across the membrane modules.
178
Which of the following freshwater generators has an operating principle that requires it to run under a substantially positive pressure?
(a) Submerged tube unit
(b) Titanium plate unit
(c) Reverse-osmosis unit
(d) Flash type unit
(c) Reverse-osmosis unit
179
Which of the freshwater generators listed below is operated without a source of heat?
(a) Titanium plate type
(b) Flash type
(c) Reverse-osmosis type
(d) Submerged tube type
(c) Reverse-osmosis type
180
A vacuum differential is maintained in the distillate circuit between any two stages of a multiple stage distilling plant by the use of a/an __________.
a) steam trap
b) butterfly valve
c) loop seal
d) adjustable controller
c) loop seal
181
Hydraulic pumps most commonly used in steering systems are of the __________.
a) lobe type
b) screw type
c) axial piston type
d) volute type
c) axial piston type
182
The follow-up gear on an electro- hydraulic steering gear __________.
a) relieves excessive fluid pressure.
b) takes the pump off stroke when the desired rudder angle is attained.
c) allows for rudder movement faster than the movement of the ship's wheel.
d) returns the rudder to amidships when the wheel is released.
b) takes the pump off stroke when the desired rudder angle is attained.
183
In an electro-hydraulic steering system, rudder movement is maintained in close synchronization with the steering wheel position by means of the __________.
a) trick wheel
b) follow-up control
c) six-way valve
d) Rapson slide
b) follow-up control
184
Under what conditions is it permissible to pump machinery space bilges directly overboard without processing by an oily water separator?
When presented with a flooding emergency.
185
If item "1" in the illustrated oily water separator indicates an abnormally deep vacuum, what condition is the most probable cause? GS-0153
Suction line inlet strainer is obstructed.
186
The components indicated as "7" and "8" as shown in the illustration, are known as the __________. GS-0153
(a) first stage oil separator and drip pan
(b) second stage oil separator and drip pan
(c) outlet weir and outlet baffle
(d) inlet weir and inlet baffle
(d) inlet weir and inlet baffle
187
What item is used to prevent over pressurization in the device shown in the illustration? GS-0153
Item #2 (pressure relief valve)
188
The unit shown in the illustration is known as a/an __________. GS-0153
oily-water separator
189
Which of the following speed control devices is used strictly as a safety device to prevent prime mover damage and acts by shutting down the prime mover?
(a) Over speed governor
(b) Speed-limiting governor
(c) Over speed trip
(d) Under speed trip
(c) Over speed trip
190
Which term represents the ability of a speed control governor to maintain prime mover speed without hunting?
(a) Dead band
(b) Stability
(c) Promptness
(d) Sensitivity
(b) Stability
191
Which term represents the how rapidly a speed control governor will complete a corrective action as the result of a load change?
(a) Sensitivity
(b) Power
(c) Promptness
(d) Dead band
(c) Promptness
192
Isochronous governors are able to maintain _______ prime mover speed regardless of _______.
constant,
| load
193
The type of gage most commonly used to measure pressure is the __________.
bourdon tube type
194
A compound gage is used to measure __________.
pressure and vacuum
195
In the device shown in the illustration, what is the function of item "6"? GS-0153
It is used to control the oil discharge mode.
| Item 6 is the sensing probe.
196
What equipment is required when processing bilge slops for overboard discharge?
A A 100 PPM oily water separator.
B A lube oil purifier operating as a separator.
C A 15 ppm oily water separator and discharge monitor.
D A 30 PPM oily water separator and discharge monitor.
C A 15 ppm oily water separator and discharge monitor.
197
Water hammer in a steam heating system can be caused by __________.
(a) filling the auxiliary boiler with cold water
(b) steam admitted to a cold pipe
(c) filling the auxiliary boiler with hot water
(d) draining a soot blower line before cracking the steam supply valve
(b) steam admitted to a cold pipe
[sudden pressure change]
198
A solenoid-operated distillate three-way valve is installed in the discharge line between the distilling plant and the potable water tanks. This valve will trip and dump the distillate discharge if the __________.
distillate salinity is excessive
199
If the evaporator feed temperature from a flash type evaporator falls below 160°F __________.
the automatic three- way solenoid dump valve should direct distillate to the bilge
200
The function of the loop seal, as typically provided on a flash type evaporator, is to __________.
transfer the distillate produced in the first stage to the second stage
201
The purpose of a three-way, solenoid, dump valve on an distilling plant evaporator is to __________.
prevent excessively saline distillate from entering the freshwater system
202
A solenoid operated distillate bypass valve is installed in the discharge line between a distilling plant and the potable water tanks to prevent __________.
salty distillate from reaching the potable tanks
203
Distilled water from an evaporator is normally discharged into a potable water tank __________.
a) through a detachable hose connection
b) after first passing through an activated charcoal filter
c) after chemical analysis shows it is fit for consumption
d) after passing through a solenoid operated dump valve energized by an alarm monitor
d) after passing through a solenoid operated dump valve energized by an alarm monitor
204
Greases used for most marine applications would have what National Lubricating Grease Institute (NLGI) grade?
2
205
Packing extremely soft grease into a roller bearing will cause __________.
high temperatures to develop as result of churning
206
The function of lubricating oil is to __________.
a) maintain a constant oil temperature
b) maintain a pressurized fluid film between moving surfaces
c) remove entrained water
d) maintain even distribution of bearing wear
b) maintain a pressurized fluid film between moving surfaces
207
The greatest difference between absorbent and adsorbent filters is that absorbent filters __________.
(a) soak up liquid contaminants directly into the filter media
(b) will remove additives from the lube oil
(c) do not create pressure drops in the lube oil system
(d) attract or have liquid contaminants stick to the surface of the filter media
(a) soak up liquid contaminants directly into the filter media
208
Adsorption filters are not commonly used in steam turbine or diesel engine lubricating systems because they __________.
remove additives from the lube oil
209
What is used to protect a direct sensing steam pressure gauge from damage from contact with steam?
(a) The installation of a damping needle valve in the entrance to the gauge.
(b) The installation of a siphon tube (pig-tail) oriented horizontally in the entrance to the gauge.
(c) The installation of thermal insulation on the gauge.
(d) The installation of a siphon tube (pig-tail) oriented vertically in the entrance to the gauge.
(d) The installation of a siphon tube (pig-tail) oriented VERTICALLY in the entrance to the gauge.
210
While riding at anchor, the anchor chain should be secured by the __________.
(a) riding spindle
(b) windlass brake only
(c) chain stopper or riding pawl
(d) anchor shackle
(c) chain stopper or riding pawl
211
```
Which of the following elements is common to all indicating instruments?
A An electrical input
B A bourdon tube
C A reset button
D A calibrated scale
```
D A calibrated scale
212
```
The purpose of the propeller fairwater cone is to __________.
A lock the propeller nut in position
B minimize water turbulence
C eliminate axial thrust
D eliminate cavitation
```
B minimize water turbulence
213
What process control system control mode is most likely to have steady-state error (also known as offset or residual error)?
(a) Proportional mode
(b) Proportional + Derivative mode
(c) Proportional + Integral + Derivative mode
(d) Proportional + Integral mode
(a) Proportional mode
214
For a process control system using the proportional control mode, what statement is true?
(a) Increasing the proportional gain without limit will always decrease the steady-state error.
(b) Increasing the proportional gain without limit will always increase the steady-state error.
(c) Increasing the proportional gain within limits will decrease the steady-state error, but too much
gain may cause instability.
(d) Decreasing the proportional gain within limits will decrease the steady-state error, but too little
gain may cause instability.
(c) INCREASING the proportional gain WITHIN limits will DECREASE the steady-state error, but too much gain may cause instability.
215
What is another name for the control mode used in a process control system that uses two-point control?
On-off control
216
If your skin comes in contact with liquid ammonia refrigerant, what should be your immediate reaction?
flush the affected area with water
217
Which chemical symbol represents ammonia?
NH3
| Ammonia is also known as R-717
218
Pigtails, or siphons, are used to protect Bourdon tube-type gages from the direct exposure to steam by __________.
creating a condensate seal
219
If you suspect that a gage is sticking and giving an inaccurate reading, you should __________.
replace the gage or have it calibrated
220
Concerning cargo-hold dehumidification, what statement is true?
(a) Cargo hold moisture content is reduced by supplying relatively dry air from the outside and exhausting relatively humid air to the outside.
(b) Cargo hold moisture content is reduced by supplying relatively humid air from the outside and exhausting relatively dry air to the outside.
(c) Cargo hold moisture content is increased by supplying relatively dry air from the outside and exhausting relatively humid air to the outside.
(d) Cargo hold moisture content is increased by supplying relatively humid air from the outside and exhausting relatively dry air to the outside.
(a) Cargo hold moisture content is REDUCED by supplying relatively DRY air from the outside and exhausting relatively humid air to the outside.
221
The duties of a chief engineer upon taking charge of the department include __________.
(a) determining if any vital engine room equipment is inoperative
(b) preparing a list of engine department personnel for the Master's signature
(c) taking a complete personal inventory of all engine room spare parts
(d) obtaining a valid Certification of Inspection from the Coast Guard
(a) determining if any vital engine room equipment is inoperative
222
```
Flame screens are used to __________ .
A contain flammable fumes
B protect firefighters from flames
C prevent flames from entering tanks
D keep flames and sparks from getting out of an engine's exhaust system
```
C prevent flames from entering tanks
223
```
According to 46 CFR, a single layer of tank vent flame screen must be composed of corrosion resistant wire and at least a mesh of __________ .
A 8 x 8
B 10 x 10
C 20 x 20
D 30 x 30
```
D 30 x 30
224
```
According to CFRs, open tank hatches from tanks which are not gas free, and unattended, must be protected by __________.
A flame screens
B warning signs
C P.V. valves
D stop-check valves
```
A flame screens
225
```
A device for preventing sparks or flames from entering a tank, while permitting the free passage of gases is called a __________.
A gas absorption detector
B pressure-vacuum relief valve
C flame screen
D sacrificial anode
```
C flame screen
226
To detect the presence of explosive gases in any space, tank, or compartment, you should use a __________.
combustible gas indicator
227
At the earliest indication of fire aboard your vessel, you must FIRST __________ .
A locate the fire
B determine which type of fire is burning
C sound the alarm
D fight the fire
C sound the alarm
228
```
Before making any welded repairs to the internals of a vessel's fuel tank in a U.S. port, the tank must be examined by __________.
A the insurance underwriter
B the master of the vessel
C the chief engineer
D a certified marine chemist
```
D a certified marine chemist
229
Fire doors are released by a/an __________.
A method that automatically releases the door in the event of a disruption of control system power
B spring-loaded catch that automatically lifts to release the door in the event of the presence of a fire
C pneumatic heat sensor
D hydraulic directional valve that automatically releases the door in the event of a disruption to the control power system
A method that automatically releases the door in the event of a disruption of control system power
230
The all-purpose, or combination nozzle is capable by itself of producing a solid stream of water __________.
(a) only
(b) and low velocity water fog
(c) and high and low velocity water fog
(d) and high velocity water fog
(d) and high velocity water fog
231
An extinguishing agent which effectively cools dilutes combustible vapors and provides a heat and smoke screen is __________.
(a) dry chemical
(b) water fog
(c) carbon dioxide
(d) Halon 1301
(b) water fog
232
Water applied as a 'fog' can be more effective than water applied as a 'solid stream', because __________.
(a) a given amount of water can absorb more heat when it is in the form of fog
(b) it reduces the total amount of water that must be pumped into the ship to fight a given fire
(c) it does not have to hit the seat of fire to be effective
(d) of all of the above
(d) all of the above
233
Before inserting a low velocity fog applicator into the device shown in the illustration, you must place the handle in __________. SF-0011
A position "C", operate catch "E", and remove piece "D"
B position "B", secure the water pressure, and turn piece "D" to your right
C position "A", depress piece "D", and open catch "E"
D position "C", secure the water pressure, and turn piece "D" to your left
A position "C", operate catch "E", and remove piece "D"
234
```
When the handle is in position "B", and piece "D" is in place, the device shown in the illustration will produce __________.
A no flow
B a solid stream
C low velocity fog
D high velocity fog
```
D high velocity fog
235
A fireman's outfit carried onboard cargo vessels, must have a __________.
(a) canister-type gas mask
(b) fresh-air breathing apparatus
(c) self-contained breathing apparatus
(d) combustible gas indicator
(c) self-contained breathing apparatus
236
```
According to 46 CFR part 95, each shipboard fire hydrant is required to have at least one spanner wrench, one length of fire hose and one __________ .
A hose stowage rack
B hand-portable extinguisher
C foam applicator
D pick ax
```
A hose stowage rack
237
The external flotation bladder on an immersion suit should be inflated __________.
AFTER you enter the water
238
When the steering gear is in operation, you should __________.
a) check hydraulic oil levels every hour
b) check the rams for overheating
c) check for excessive oil leakage from rams
d) drain water from telemotor cylinders each watch
c) check for excessive oil leakage from rams
239
The reading of a combustible gas indicator indicates the percentage of the __________.
a) concentration of flammable gas in a compartment
b) lower explosive limit of a flammable gas concentration
c) upper explosive limit of a flammable gas concentration
d) concentration by weight of nonflammable gas in a compartment
b) lower explosive limit of a flammable gas concentration
240
Your vessel has run aground and upon taking fuel oil tank soundings, you find that a fuel tank level has increased. You therefore should suspect __________.
a crack in the hull portion of the fuel tank
241
In the absence of external forces, the center of gravity of a floating vessel is located directly above the __________.
(a) center of flotation
(b) amidships
(c) geometric center of the displaced volume
(d) metacenter
(c) geometric center of the displaced volume
242
Stability is determined principally by the relationship of the center of gravity and the __________.
(a) keel
(b) center of buoyancy
(c) center of flotation
(d) aft perpendicular
(b) center of buoyancy
243
A vessel's center of gravity is lowered when the __________.
(a) freeboard is increased
(b) tanks are ballasted
(c) trim is increased
(d) reserve buoyancy increases
(b) tanks are ballasted
244
Which of the listed conditions will occur to the ship's center of gravity if 200 tons of steel is transferred to the ship’s cargo hold from shore side?
(a) The center of gravity will remain in the same position. (b) The reserve buoyancy will rise.
(c) The center of gravity will be lowered.
(d) The reserve buoyancy will remain the same.
(c) The center of gravity will be lowered.
245
Through which of the listed components is flash gas formation a normal occurrence?
(a) receiver tank
(b) thermostatic expansion valve
(c) evaporator coil
(d) condenser coil
(b) thermostatic expansion valve
246
What is the physical state and pressure condition of refrigerant as it enters the condenser of a typical refrigeration system.
(a) low pressure vapor
(b) low pressure liquid
(c) high pressure vapor
(d) high pressure liquid
(c) high pressure vapor
247
What is the physical state and pressure condition of refrigerant as it leaves a receiver in a typical refrigeration system?
(a) low pressure vapor
(b) high pressure vapor
(c) low pressure liquid
(d) high pressure liquid
(d) high pressure liquid
248
Refrigerant entering the compressor of a refrigeration system should be in which of the following conditions?
(a) Low pressure vapor
(b) High pressure liquid
(c) High pressure vapor
(d) Low pressure liquid
(a) Low pressure vapor
249
The high pressure side of the refrigeration system, as shown in the illustration, in the order of flow, is located between what two components? GS-RA-02
a) "5" and "10"
b) "1" and "5"
c) "11" and "7"
d) "7" and "11"
c) "11" and "7"
The HIGH side is from the discharge side of the compressor to the thermal expansion valve inlet.
250
The low pressure side of the refrigeration system, as shown in the illustration, in the order of flow, is located between what two components? GS-RA-02
a) "5" and "10"
b) "1" and "5"
c) "11" and "7"
d) "7" and "11"
d) "7" and "11"
The LOW side is from the discharge side of the thermal expansion valve to the compressor inlet.
251
Subcooling is a method of reducing the temperature of the liquid refrigerant below what temperature or point?
a) freezing point
b) floc point
c) condensing temperature
d) compression temperature
c) condensing temperature
252
What is the principal purpose of subcooling liquid refrigerant prior to its entering the expansion valve?
a) increase the refrigerating effect by decreasing the amount of flash gas
b) allow the refrigerant to enter the throttling device in a saturated condition
c) increase the refrigerating effect by increasing the amount of flash gas
d) minimize the temperature drop of the liquid as it passes through the solenoid valve to the outlet side
a) increase the refrigerating effect by decreasing the amount of flash gas
253
The process of removing moisture from air is known as what?
Dehumidification
254
The component of a refrigerating system in which the refrigerant vaporizes and absorbs heat is known as what?
Evaporator
255
```
In which of the listed refrigeration system components does superheating of the refrigerant take place?
Expansion valve
Evaporator
Drier
Receiver
```
Evaporator
256
In a typical refrigeration system, where is the temperature of the refrigerant gas at the highest?
At the compressor discharge
257
One refrigeration ton is equal to which of the following heat removal rates?
a) 180 BTU/hr
b) 2,000 BTU/hr
c) 12,000 BTU/hr
d) 2,880,000 BTU/day
c) 12,000 BTU/hr
258
How much heat per hour can a 5 ton refrigeration unit remove from a refrigerated space?
a) 60,000 BTU/hr
b) 80,000 BTU/hr
c) 100,000 BTU/hr
d) 120,000 BTU/hr
a) 60,000 BTU/hr
[5 ton x 12,000 BTU]
259
In a refrigeration system, the amount of superheat absorbed by the refrigerant flowing through the evaporator coil is adjusted at what device?
the thermal expansion valve
260
What parameter is the thermostatic expansion valve designed to maintain constant?
a) refrigerant flow
b) box temperature
c) evaporator superheat
d) evaporator pressure
c) evaporator superheat
261
When liquid reaches the compressor of a refrigeration system through the suction line, what is this condition called?
a) flooding back
b) superheating
c) overflowing
d) recycling
a) flooding back
262
Do different refrigerants have different corresponding oils to be used?
Yep
263
In a mechanical refrigeration system, in addition to the high and low side pressure differential, what is the amount of refrigerant admitted to the evaporator directly related to?
a) the degree of opening of the king solenoid valve
b) the degree of opening of the water regulating valve
c) the degree of opening of the box solenoid valve
d) the degree of opening of the expansion valve
d) the degree of opening of the expansion valve
264
Which of the fluids listed is suitable for use as a secondary refrigerant?
(a) Carbon dioxide
(b) Cuprous chloride
(c) Methyl alcohol
(d) Brine
(d) Brine
265
Which of the listed refrigeration system components keeps the refrigerant circulating through the system?
a) Expansion valve
b) Condenser
c) Evaporator
d) Compressor
d) Compressor
266
An increase in the heat load subjected to a refrigeration system will cause what to happen?
a) the compressor suction pressure to decrease
b) the compressor suction pressure to increase
c) increased ice formation on the evaporator coil
d) excessive short cycling of the compressor
b) the compressor suction pressure to increase
267
Refrigerants that experience fractionation when changing state are characterized as what?
a) azeotropic mixture of refrigerants
b) single component organic refrigerants
c) zeotropic blend of refrigerants
d) single component inorganic refrigerants
c) zeotropic blend of refrigerants
[Fractionation is the change in composition of a blend because one or more of the components is lost or removed faster than the other(s).]
268
Which of the following forms of heat is removed from the refrigerant in the condenser of a refrigeration system?
a) Latent heat of vaporization
b) Heat of compression
c) Superheat
d) All of the above
d) All of the above
269
The only means of removing the latent heat of condensation from a refrigerant in the normal refrigeration cycle is by performing what process?
a) passing it through the expansion valve
b) condensing refrigerant in the system condenser
c) passing the gaseous refrigerant through the heat interchanger on the suction side of the compressor
d) maintaining a high pressure on the system's receiver
b) condensing refrigerant in the system condenser
270
Which chemical, when released into the atmosphere, has been found to eventually reach the stratosphere and react unfavorably with the earths ozone layer?
a) fluorine
b) chlorine
c) nitrogen
d) carbon
b) chlorine
271
If a refrigerated space has associated with it a heat load of 60,000 BTU/hour, what size refrigeration unit would be required?
a) 3 ton
b) 4 ton
c) 4.5 ton
d) 5 ton
d) 5 ton
[60,000 BTU / 12,000 BTU]
272
Which of the listed statements is correct concerning refrigeration system heat removal capacity is true?
a) One refrigeration ton is equivalent to the removal of 144,000 btu per hour
b) One refrigeration ton is equivalent to the removal of 12,000 btu per day
c) One refrigeration ton is equivalent to the removal of 144,000 btu per day
d) One refrigeration ton is equivalent to the removal of 12,000 btu per hour
d) One refrigeration ton is equivalent to the removal of 12,000 btu per hour
273
A box solenoid valve used in a multi-box refrigeration system is operated by electro- magnetic action by what control device?
(a) evaporator outlet temperature actuated thermostat o (b) discharge pressure actuated pressure switch
(c) suction pressure actuated pressure switch
(d) box temperature actuated thermostat
(d) box temperature actuated thermostat
274
What is the pressure and condition of the refrigerant entering the receiver of a refrigeration system?
(a) superheated low pressure vapor
(b) sub cooled low pressure liquid
(c) superheated high pressure vapor
(d) sub cooled high pressure liquid
(d) sub cooled high pressure liquid
275
An economizer, or heat interchanger, is installed in a refrigeration system for what purpose?
a) lower the temperature of liquid refrigerant before entering the expansion valve
b) reduce the possibility of liquid refrigerant from flooding back to the compressor
c) minimize sweating of the suction line
d) All of the above.
d) All of the above.
276
When air at a given temperature contains the maximum amount of moisture for that temperature, what term describes what the air is considered to be?
a) superheated
b) saturated
c) condensing
d) evaporating
b) saturated
277
In which of the listed refrigeration system components does superheating of the refrigerant take place?
a) Expansion valve
b) Evaporator
c) Drier
d) Receiver
b) Evaporator
278
An increase in the heat load subjected to a refrigeration system will cause what to happen?
a) the compressor suction pressure to decrease
b) the compressor suction pressure to increase
c) increased ice formation on the evaporator coil
d) excessive short cycling of the compressor
b) the compressor suction pressure to increase
279
Which of the following refrigerants is an interim retrofit replacement for R-11?
a) R-500
b) R-134a
c) R-12
d) R-123
R-123
280
In a refrigeration system, the amount of superheat absorbed by the refrigerant flowing through the evaporator coil is adjusted at what device?
TXV
281
A thermostatic expansion valve is designed to respond directly to changes in which of the following parameters?
a) refrigerated space temperature
b) compressor suction pressure
c) liquid line temperature
d) evaporator superheat
d) evaporator superheat
282
Which component is the refrigeration system condenser? GS-RA-02
3
283
Which component is the refrigeration system evaporator? GS-RA-02
8
284
What temperature associated with the psychrometric properties of air is measured by an ordinary thermometer?
(a) The dry-bulb temperature
(b) The wet-bulb temperature
(c) The dew-point temperature
(d) The saturation temperature
(a) The dry-bulb temperature
285
Referring to the illustrated psychrometric chart, under what conditions are the dry- bulb, wet-bulb, and dew point temperatures for air all equal in value? (GS-RA-22)
(a) When the relative humidity is 0%.
(b) It is impossible for the dry-bulb, wet-bulb, and dew point temperatures to be the same value.
(c) When the air is completed saturated with moisture and the relative humidity is 100%.
(d) When the grains of moisture per pound of dry air is zero.
(c) When the air is completed saturated with moisture and the relative humidity is 100%.
286
If outside air at 80 degrees F and 70 percent relative humidity is conditioned, what will be the resulting dew point temperature of the air just before it comes into contact with the cooling coil? Illustration GS-RA-22
(a) 64 degrees F
(b) 70 degrees F
(c) 73 degrees F
(d) 67 degrees F
(b) 70 degrees F
287
What is the wet bulb temperature of air if the dry bulb temperature of the air is 90 degrees and the relative humidity is 65%? Illustration GS-RA-22
(a) 80 degrees F
(b) 63 degrees F
(c) 77 degrees F
(d) 62 degrees F
(a) 80 degrees F
288
The introduction of outside air to the air conditioning system is 90°F with a relative humidity of 60%. The air has been conditioned to 70°F with a relative humidity of 80%. Using the psychrometric chart, shown in the illustration, determine the quantity of moisture removed from one pound of the conditioned air. See Illustration GS-RA-22
(a) 40 grains
(b) 50 grains
(c) 30 grains
(d) 20 grains
(a) 40 grains
289
The device shown in the illustration is used for what purpose? GS-RA-13
a) refrigeration compressor capacity control unloading mechanism
b) air conditioning proportional-plus- reset, humidity/ temperature ratio controller
c) multi-box back pressure regulator with surge chamber
d) combined box temperature thermostat and thermal expansion device
a) refrigeration compressor capacity control unloading mechanism
290
The fluid used as a source of actuating power against the underside of the unloader power element piston of the refrigeration compressor capacity control mechanism illustrated is obtained from where? GS-RA-13
(a) discharge of a secondary hydraulic pump specifically installed for this operation
(b) high side liquid receiver
(c) gas discharge from the compressor
(d) discharge of the compressor lube oil pump
(d) discharge of the compressor lube oil pump
291
Referring to illustrated diagram, what type of HVAC system is shown? (GS-RA-09)
(a) A dual duct system
(b) A terminal reheat system
(c) A variable air volume system
(d) A single zone system
(d) A single zone system
292
Referring to illustrated diagram, what type of HVAC system is shown? (GS-RA-42)
(a) A dual duct system
(b) A terminal reheat system
(c) A variable air volume system
(d) A single zone system
(b) A terminal reheat system
293
A reheater, as used in an air conditioning system, is designed to control what temperature?
a) chilled water temperature
b) dew point temperature
c) primary air temperature
d) dry bulb room temperature
d) dry bulb room temperature
294
To prevent the unnecessary loading of an air conditioning system while maintaining the designed dry bulb temperature and relative humidity in an air conditioning system, what should be done?
a) admit only enough fresh outside air to provide proper ventilation
b) reduce the air reheating system load
c) lower the compressor head pressure
d) operate the purge recovery unit continuously
a) admit only enough fresh outside air to provide proper ventilation
295
In an air conditioning system, moisture is removed from the air by what means?
a) filters
b) separators
c) ducted traps
d) cooling coils
d) cooling coils
296
The safety device which normally stops a running refrigeration compressor before the relief valve starts to open is known as what?
a) low pressure cutout switch
b) back pressure cutout switch
c) high pressure cutout switch
d) relief valve bypass
c) high pressure cutout switch
297
A refrigerant used in a mechanical refrigeration system should have which of the following characteristics?
a) High boiling point
b) High freezing point
c) Low specific heat
d) Low boiling point
d) Low boiling point
298
How is the amount of refrigerant in a storage cylinder measured?
a) pressure
b) volume
c) weight
d) temperature
c) weight
299
Refrigerant leaving the metering device in a refrigeration system is in which of the following conditions?
a) sub-cooled liquid only
b) superheated vapor only
c) saturated liquid/vapor mixture
d) superheated liquid/vapor mixture
c) saturated liquid/vapor mixture
300
What is the name of the device used to remove moisture from a refrigeration system?
a) humidifier
b) aerator
c) dehydrator
d) trap
c) dehydrator
