DDE General Sub/Safety/HVAC Flashcards
The purpose of annealing any metal is to make the metal __________.
softer
Reheating a hardened component to a temperature LOWER than the hardening temperature and then cooling it is known as __________.
tempering
To anneal a copper gasket, you should heat the gasket __________.
cherry red and quench in water
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?
Softened condition
Copper sheet metal that is to be used as a gasket, is usually annealed by heating it to a cherry red color, and then __________.
dousing it in cold water
Tubing is sized by __________.
nominal outside diameter
After adding grease to a ball bearing with a handheld grease gun, you should __________.
run the machine with the bearing housing drain plug open for a short while
What material is most commonly used as a sacrificial anode for the purposes of minimizing the galvanic corrosion of steel and cast iron?
Zinc
If water continues to flow excessively from the device shown in the illustration, the problem is most likely due to __________. GS-0155
item “H” being fouled or plugged
The diaphragm orifice labeled “H”, as shown in the illustration is used as a/an __________. GS-0155
time delay
The device shown in the illustration is a __________. GS-0155
flushometer valve (Sloan valve)
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
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.
How often should the air receivers on a compressed air system be drained of moisture and emulsions?
Daily
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
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
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 __________ .
fusion
The heat identified by only a change in temperature is known as __________.
Sensible heat
A tailstock ‘dead center’ has been given that name because it __________.
does not revolve
The drains of lavatory sinks are fitted with P-type or S-type traps to __________.
provide a seal against sewer gas rising into the compartment
If the orifice in the loop seal of a flash evaporator were to become significantly enlarged through erosion, the __________.
evaporator absolute pressure could eventually equalize in both stages to that of the second
stage
Work that cannot readily be mounted between lathe centers is usually held in a __________.
chuck
The lathe tool shown as figure “T” in the illustration is commonly known as a/an __________. GS-0090
right-cut roughing tool
The lathe tool shown as “Q” in the illustration is a __________. GS-0090
left hand side facing tool
The main difference between a common lathe dog and a safety lathe dog is that the latter __________.
has a headless set screw
The lathe tool shown as figure “U” in the illustration is commonly known as a/an __________. GS-0090
cutting-off tool
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.
Who is in charge during bunkering?
PIC, usually the chief
The minimum firefighting equipment to be maintained onboard a tank vessel, can be determined from the __________.
vessel’s Certificate of Inspection
A characteristic of lubricating oil which causes additional centrifuging requirements for proper purification is __________.
low oil demulsibility
demulsibility of a lube oil is defined as __________ .
the ability of oil to separate from water
The ability of an oil to separate cleanly from an oil and water mixture is referred to as its __________ .
demulsibility
A ball bearing will overheat if __________.
completely packed full of grease
Which of the listed types of files is the best for producing a fine finish on metal?
Mill
During oil transfer operations, who would be responsible to guarantee that the posted transfer procedures are being followed?
The designated person in charge
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.
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.
Safety valves are designed to open _____ when lifted by excessive pressure and only reseat when the pressure has __________.
wide,
dropped significantly
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.
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.
To properly remove packing from a valve stuffing box, you should use a __________.
packing puller (or packing hook)
The basic function of the centrifugal pump impeller is to __________.
directly increase the velocity of the liquid being pumped
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by __________.
cavitation
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
A distinguishing feature of an eductor, when compared to other pumps, is the __________.
lack of moving parts
Zincs are installed in the main and auxiliary condenser water boxes to __________.
reduce the effects of electrolysis
When hardened metal is heat-treated by a process known as tempering, what metallurgical properties are achieved?
decrease in brittleness
What is the benefit of using water fog in firefighting?
Fog absorbs a lot of heat due to it’s greater surface area.
Pump pressure can also be expressed as _______.
feet of head
A pressure reading of 00.0 psig is theoretically equal to __________.
14.7 psia
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
In the illustration, line “C” is a __________. GS-0006
dimension line
In the illustration, line “D” is a/an __________. GS-0006
hidden line
In the illustration, line “J” is used to depict a _________? GS-0006
cutting plane line
Figure “B”, shown in the illustration, is dimensioned to indicate a/an __________. GS-0019
interference fit
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”
How many hidden lines are shown in the right side (end) view of the drawing illustrated? GS-0021
None
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
The reading on the vernier caliper scale shown in figure “G” in the illustration is __________. GS-0082
2.368 inches
For greater accuracy, some micrometers have a vernier scale making it possible to read in increments of __________.
ten thousands of an inch
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
Enlarging one tube end so the end of another tube of the same size will fit inside is termed __________.
swaging
The tool shown in the illustration is called a __________. GS-0072
Center gage
In machine shop practice, a center gage is used for checking the angle of __________.
60° thread cutting tools
A gate valve installed in a piping system should be used __________.
in either fully closed or fully opened positions
Lantern rings are provided on centrifugal pumps to __________.
provide a passage for the stuffing box sealing liquid
Specific gravity of mercury =
13.56
The device shown in the illustration is commonly known as a/an __________. GS- 0071
mechanical seal
An increase in rotor clearances in a rotary pump will __________.
decrease pump capacity
What causes cavitation in a centrifugal pump?
Vapor pockets in the flow stream
One of the consequences in continuing to operate a centrifugal pump with the discharge valve closed, is that the __________.
pump will overheat
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
A centrifugal pump may fail to deliver water when first started if the __________.
pump is not primed
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.
A fully charged standard SCBA can be expected to supply air under non-stressful conditions for approximately __________.
30 minutes
In pressure measurement, absolute pressure is defined as the difference in pressure between __________ .
a perfect vacuum and the total pressure at a given point
If one drive belt on an air compressor is found to be worn you should __________.
replace all of the belts
When removing roller bearings from a shaft, the force of the puller should be applied to the bearing __________.
inner race
Why do roller bearings have higher loading capacities than ball bearings?
They have a greater contact area.
What mode of heat transfer is associated with the transport of thermal energy from one location to another by fluid in motion?
Convection
What mode of heat transfer is associated with the transport of thermal energy within a body or between two bodies in direct contact?
Conduction
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
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
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)
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)
The illustrated valve is known as a __________. GS-0056
swing check valve
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
The hydraulic graphic symbol illustrated as Fig. C is used to depict a/an __________ . GS-0068
variable output, single direction flow pump
The hydraulic graphic symbol illustrated in Fig. B is used to represent a/an __________ . GS-0068
variable orifice
Which of the devices shown in the illustration is designed for both inside and outside measurements? GS-0073
C
The general purpose of a heat exchanger is to __________.
heat, or cool one fluid by means of another fluid
Pressure in an operating hydraulic system is developed __________.
by resistance to the fluid flow through the system
Energy imparted to the hydraulic fluid in an operating hydraulic system is stored in the __________.
accumulator
How many BTUs must be added to one pound of water at 32°F to raise the temperature to 212°F?
180 BTUs
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
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
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
One cubic foot of salt water would equal approximately how many pounds?
64
Bronze metal is an alloy composed mainly of __________.
copper and tin
Brass metal is an alloy composed mainly of __________.
copper and zinc
A ‘close nipple’ is a piece of pipe that is __________.
threaded along the entire length
The size of ball and roller bearings can be identified by the __________.
manufacturer’s numerical code
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
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
Which of the following terms is used to identify the pressure of a liquid entering a centrifugal pump?
Suction head
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.
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
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
How is a vacuum is created by a jet pump or an eductor?
A rapidly moving stream of fluid passing through a nozzle.
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
Reduced capacity, accompanied by vibration and noise at the suction of a centrifugal pump is a result of __________.
cavitation
If the capacity of a centrifugal pump decreases gradually over a long period of time, you should replace the __________.
wearing rings
An air compressor is equipped with an intercooler and an aftercooler to __________.
increase compressor efficiency and economy
The unloading system on an air compressor will __________.
allow the motor to turn the compressor opposed only by friction
Air compressor cylinder unloaders enable the compressor to __________.
start and come up to speed before air compression begins
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
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
The counterbalance valve (5) in the winch circuit shown in the illustration ________. GS-0161
helps prevent slung loads from dropping prematurely
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)
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.
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.
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”
