U.S.C.G. Merchant Marine Exam DDE – Unlimited HP Q624 ...Q624 General Subjects U.S.C.G. Merchant...

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U.S.C.G. Merchant Marine Exam

DDE – Unlimited HP

Q624 General Subjects

(Sample Examination)

of 40 Q624 General Subjects

8/22/2019

Q624 General Subjects U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 21

Choose the best answer to the following Multiple Choice Questions

1. Which of the following bilge pumping applications would most likely use a non-automated centrifugal pump under manual supervision?

o (A) Machinery space bilges o (B) Engine room bilges • (C) Dry cargo-hold bilges o (D) Shaft alley bilges

If choice C is selected set score to 1.

2. Which of the following compressors would be used for a dead ship start-up of a ship's service diesel-generator on a motor ship?

• (A) Emergency air compressor o (B) Topping air compressor o (C) Ship's service air compressor o (D) Starting air compressor

If choice A is selected set score to 1.

3. Which of the following statements represents the proper criteria to decide when to drain a filter/moisture separator as used in a ship's service air system hose station?

o (A) The bowl should be drained whenever moisture droplets appear in the bowl. o (B) The bowl should be drained daily with no need to check the moisture level. o (C) The bowl should be drained after the bowl completely fills with moisture. • (D) The bowl should be drained before the moisture level reaches the lower baffle.

If choice D is selected set score to 1.

4. As shown in figure "A" of the illustrated block diagram of a central operating system configured for direct digital control, what does the output system block "ANALOG A/D" represent? Illustration EL-0095

o (A) It receives analog outputs from the analog device sensors and conditions these as analog signals for CPU processing.

• (B) It receives analog outputs from the analog device sensors and converts these to digital signals for CPU processing.

o (C) It receives digital outputs from the binary device sensors and conditions these as digital signals for CPU processing.

o (D) It receives digital outputs from the binary device sensors and converts these to analog signals for CPU processing.

If choice B is selected set score to 1.


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Q624 General Subjects U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 21 5. In a closed-loop process control system, what statement concerning feedback is true as it relates to

stability and the direction of error displacement?

o (A) Positive feedback is used to minimize instability by pushing the system in the opposite direction as the error displacement.

• (B) Negative feedback is used to minimize instability by pushing the system in the opposite direction as the error displacement.

o (C) Negative feedback is used to minimize instability by pushing the system in the same direction as the error displacement.

o (D) Positive feedback is used to minimize instability by pushing the system in the same direction as the error displacement.


6. Which of the fresh water generators listed below is operated without a source of heat?

o (A) Titanium plate type o (B) Flash type o (C) Submerged tube type • (D) Reverse osmosis type


7. With respect to shaft bearing load absorption capability in terms of direction, what is meant by an axial load?

o (A) An axial load is a load applied tangent to the circumference of the shaft. • (B) An axial load is a load applied parallel to the axis of the shaft. o (C) An axial load is a load applied perpendicular to the axis of the shaft. o (D) An axial load is a load applied perpendicular and parallel to the axis of the shaft.


8. What is the primary indication of a grease lubricated bearing that is over-lubricated in terms of the quantity of grease in the housing?

o (A) The bearing would tend to produce a noticeable change in sound. • (B) The bearing temperature would tend to run hotter than normal for the load. o (C) The bearing temperature would tend to produce unusual vibrations. o (D) The bearing temperature would tend to run cooler than normal for the load.



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9. For the successful operation of a reverse osmosis fresh water generator, why is the high-pressure pump required to operate in the 750 to 1200 psig range for a discharge pressure?

o (A) To successfully force the salt water through the chemical pre-treatment device. o (B) To overcome the pore size of the semi-permeable membrane. • (C) To overcome the osmotic pressure generated by the difference in solution concentrations. o (D) To successfully force the salt water through the pre-filter (or pre-filters).


10. For the operation of the illustrated device, what fluid flow would be expected at the connection labeled "I"? Illustration MO-0110

o (A) The distillate discharge. • (B) The sea water used for condensing the water vapor. o (C) Main engine jacket water. o (D) The salt water feed.


11. According to the illustration, which of the following conditions would most likely cause pump "A" to short cycle? Illustration GS-0173

• (A) The hydro-pneumatic expansion tank is operating with an insufficient air charge. o (B) The hydro-pneumatic tank is operating with a low water level. o (C) A low water level exists in the potable water storage tank. o (D) Pump "A" wearing rings have excessive clearance.


12. Which term represents the ability of a speed control governor to maintain prime mover speed without hunting?

o (A) Promptness • (B) Stability o (C) Deadband o (D) Sensitivity



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13. If both the shell-and-tube lube oil cooler and shell-and-tube jacket water cooler of a diesel engine are sea water-cooled, what statement is true?

o (A) Sea water flows through the shells of both the lube oil and jacket water coolers. o (B) Sea water flows through the tubes of the lube oil cooler and through the shell of the jacket

water cooler. o (C) Sea water flows through the tubes of the jacket water cooler and through the shell of the lube

oil cooler. • (D) Sea water flows through the tubes of both the lube oil and jacket water coolers.


14. When placing a shell-and-tube heat exchanger with a non-removable tube bundle such as a lube oil cooler with fixed tube sheets into service, to avoid thermal shock what statement represents the correct operating procedure?

o (A) Introduce both the cooling water and the lubricating oil simultaneously establishing full flow of both fluids immediately to avoid thermal shock.

o (B) Introduce the cooling water first, then gradually introduce the lube oil until full flow is established to avoid thermal shock.

• (C) Introduce both the cooling water and the lubricating oil simultaneously and gradually to avoid thermal shock.

o (D) Introduce the lubricating oil first, then gradually introduce the cooling water until full flow is established to avoid thermal shock.


15. Energy losses occurring in a hydraulic system are ultimately absorbed by the __________.

o (A) reservoir expansion chamber o (B) hydraulic piping flexibility o (C) fluid as friction • (D) atmosphere as heat


16. A flare-type tubing connector is used in the hydraulic hatch cover system and has developed a slight leak. To stop the leak you should __________.

• (A) shut down the power unit and use two wrenches to avoid damaging the tubing when tightening

o (B) keep the system in operation and tighten the flare nut o (C) replace both the tubing sections and the fitting o (D) stop the system and use only one wrench to tighten the flare nut



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Q624 General Subjects U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 21 17. A hydraulic fluid flow control circuit, used to control linear actuator speed during retraction, with the

pump operating at above maximum pressure, is known as a __________.

o (A) bleed-off circuit • (B) metered-out circuit o (C) bleed-in circuit o (D) metered-in circuit


18. Which of the listed pressure control valves would be used to permit the completion of one action of a hydraulic system before a second action would be permitted?

• (A) Sequence valve o (B) Pressure-reducing valve o (C) Counterbalance valve o (D) Unloading valve


19. If you attempt to tighten a leaking hydraulic fitting with pressure on the system, you will __________.

o (A) dislodge any scale in the tubing, and it will damage the system o (B) be successful every time • (C) find that the pressure will prevent the components from being tightened o (D) cause the system to vibrate


20. In which lubrication application is a detergent type oil most likely to be used?

o (A) Air compressor lubricating oil. o (B) Steam turbine lubricating oil. o (C) Crosshead diesel engine bearing lubricating oil. • (D) Trunk type diesel engine lubricating oil.



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21. If the bearings of a piece of machinery are force-fed by a pressure feed lubricating oil system, which statement is true?

• (A) The lube oil pump draws a suction on the lube oil reservoir/sump and discharges directly to the bearings. The return oil then gravity drains to the lube oil reservoir/sump.

o (B) The lube oil pump draws a suction on the lube oil gravity tank and discharges directly to the bearings. The return oil then gravity drains to the lube oil gravity tank.

o (C) The lube oil pump draws a suction on the lube oil reservoir/sump and discharges directly to the bearings. The return oil then gravity drains to the lube oil gravity tank which overflows to the lube oil reservoir/sump.

o (D) The lube oil pump draws a suction on the lube oil reservoir/sump and discharges to the lube oil gravity tank. The oil then gravity feeds the bearings and the return oil drains to the lube oil reservoir/sump.


22. Which of the filter/strainer units listed permits you to replace or clean the element while leaving the system on the line?

o (A) Bypass o (B) Simplex o (C) Canister • (D) Duplex


23. What is meant by the term tensile strength of a material?

o (A) The ability to resist compression stresses. o (B) The ability to resist bending stresses. o (C) The ability to resist shearing stresses. • (D) The ability to resist stretching stresses.


24. What type of oil as part of an oily-water mixture is most likely to require heating to facilitate separation in an oily-water separator?

o (A) Steam turbine lubricating oil. o (B) Diesel engine lubricating oil. o (C) Marine diesel oil. • (D) Heavy residual fuel oil.



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25. The line labeled "C", as shown in the illustration, would be identified as the ______. Illustration GS-0175

• (A) clean water inlet line o (B) processed water outlet line o (C) waste oil discharge line o (D) oily bilge water inlet line


26. If item "1" shown in the illustration is a compound gage indicating zero psig and the water level in the bilges is one foot high, the unit is __________. Illustration GS-0153

o (A) in the oil discharge mode • (B) not turned on o (C) processing the bilge water o (D) damaged and should not be used


27. Suppose the illustrated self-contained, internal-pilot, piston-operated temperature control valve is part of the temperature control system for a steam-heated heavy fuel oil service heater for a steam boiler. If there was an increase in demand for fuel by the boiler, what statement correctly represents how the valve would initially respond? Illustration GS-0045

o (A) The fuel oil heater fuel outlet temperature would increase, causing the remote bulb pressure to increase and the thermostatic diaphragm to flex upward and through lever action, further open the pilot valve.

• (B) The fuel oil heater fuel outlet temperature would decrease, causing the remote bulb pressure to decrease and the thermostatic diaphragm to flex upward and through lever action, further open the pilot valve.

o (C) The fuel oil heater fuel outlet temperature would increase, causing the remote bulb pressure to increase and the thermostatic diaphragm to flex downward and through lever action, further close the pilot valve.

o (D) The fuel oil heater fuel outlet temperature would decrease, causing the remote bulb pressure to decrease and the thermostatic diaphragm to flex downward and through lever action, further close the pilot valve.



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28. Suppose the pilot pressure range is from 3 to 15 psig for the illustrated pneumatically operated diaphragm actuated control valve. Assuming the control valve is trimmed for a linear response and the travel position indicator is calibrated in percentage, what would be the approximate valve position with a 9 psig pilot pressure? Illustration GS-0051

o (A) 25% open o (B) 33% open • (C) 50% open o (D) 75% open


29. In the figure shown in the illustration, the standard blueprint symbols above the letters "A", "B", and "C" indicate __________. Illustration GS-0036

• (A) the use of internal threads o (B) hole tolerance o (C) finished diameter o (D) interference fit


30. The working depth of the gear illustrated is represented by __________. Illustration GS-0111

• (A) A o (B) B o (C) C o (D) I


31. What statement is true concerning the purpose of an independent main thrust bearing where used?

o (A) The main purpose of the main thrust bearing is to absorb axial thrust and maintain the shaft in proper axial alignment.

o (B) The main purpose of the main thrust bearing is to absorb radial thrust and to transmit the radial thrust developed by the propeller to the ship's hull.

o (C) The main purpose of the main thrust bearing is to absorb radial thrust and maintain the shaft in proper radial alignment.

• (D) The main purpose of the main thrust bearing is to absorb axial thrust and to transmit the axial thrust developed by the propeller to the ship's hull.



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32. Of the following propulsion modes, which one would operate with a geared-drive featuring a double reduction?

o (A) Slow-speed diesel o (B) Medium-speed diesel o (C) High-speed diesel • (D) Gas turbine


33. Reduced capacity, accompanied by vibration and noise at the suction of a centrifugal pump, results from cavitation in the fluid being pumped. Cavitation describes the formation of __________.

o (A) fluid friction o (B) steam knock o (C) water hammer action • (D) vapor pockets


34. A pump shaft that is bent or distorted should normally be __________.

o (A) reconditioned by metalizing and machining o (B) straightened by applying heat and torsion • (C) replaced with a satisfactory spare o (D) repaired by a suitable welding process


35. The reading on the micrometer scale shown in figure "D" in the illustration is __________. Illustration GS-0081

o (A) 0.4710 inch o (B) 0.4715 inch o (C) 0.4810 inch • (D) 0.4815 inch


36. The locking plates shown in the illustration are used in many marine applications. Which figure indicates the improper method for using these devices? Illustration GS-0156

o (A) "A" o (B) "B" • (C) "C" o (D) "D"



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Q624 General Subjects U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 21 37. As it applies to a transverse-framed ship with double bottom construction, what does the term "floor"

represent?

• (A) Floors are vertical transverse members supporting the inner-bottoms. o (B) Floors are the actual outer-bottom shell plating. o (C) Floors are vertical longitudinal members supporting the inner-bottoms. o (D) Floors are the actual inner-bottom tank tops.


38. What statement is true concerning the plating meeting at the gunwales of a ship?

• (A) The strakes of side plating nearest to the deck are termed "sheer strakes" and the deck plating nearest to the side are termed "stringer plates". The sheer strakes and stringer plates meet at the gunwales.

o (B) The strakes of side plating nearest to the deck and the deck plating nearest to the side are both termed "sheer strakes". These sheer strakes meet at the gunwales.

o (C) The strakes of deck plating nearest to the sides are termed "sheer strakes" and the side plating nearest to the deck are termed "stringer plates". The sheer strakes and stringer plates meet at the gunwales.

o (D) The strakes of side plating nearest to the deck and the deck plating nearest to the side are both termed "stringer plates". These stringer plates meet at the gunwales.


39. What statement is true concerning watertight doors fitted below the waterline of a vessel?

o (A) Watertight doors below the waterline may be either of the horizontal sliding type or the swinging hinged type.

o (B) Watertight doors below the waterline may be either of the vertical sliding type or the swinging hinged type.

• (C) Watertight doors below the waterline may be either of the vertical or horizontal sliding type. o (D) Watertight doors below the waterline may be of the vertical or horizontal sliding type or the

swinging hinged type.



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40. In accordance with international MARPOL Annex I regulations and the federal regulations under 33 CFR Subchapter O (Pollution), for oceangoing ships of 400 gross tons and above but less than 10,000 gross tons, what is the required means for preventing pollution by oil as it pertains to handling bilge slops?

o (A) The oceangoing ship of 400 gross tons and above but less than 10,000 gross tons is EITHER required to retain onboard all oily mixtures either in the bilges or in a slops tank and required to be equipped to discharge these mixtures to a reception facility, OR the ship is required to be equipped with an approved oily-water separator.

• (B) The oceangoing ship of 400 gross tons and above but less than 10,000 gross tons is required to be equipped with an approved 15 parts per million oily-water separator, but it is NOT required to have a high bilge oil content alarm or a means to automatically stop the oily-water discharge when the oil content exceeds 15 ppm.

o (C) The oceangoing ship of 400 gross tons and above but less than 10,000 gross tons is required to be equipped with an approved 15 parts per million oily-water separator, and it is required to have a high bilge oil content alarm and a means to automatically stop the oily-water discharge when the oil content exceeds 15 ppm.

o (D) The oceangoing ship of 400 gross tons and above but less than 10,000 gross tons is required to retain onboard all oily mixtures in a slops tank, and it is required to be equipped to discharge these mixtures to a reception facility.


41. A spur gear pump should be operated with the discharge valves __________.

o (A) slightly opened • (B) fully opened o (C) throttled o (D) halfway opened


42. The output volume of a positive fixed displacement pump can be changed only by __________.

o (A) moving the shaft trunnion block o (B) moving the slide block and rotor • (C) changing the speed of the pump o (D) changing the angle of the tilting plate



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43. Which of the following methods applies to how a vacuum is created by a jet pump or an eductor?

o (A) Centrifugal force converted into potential energy. o (B) A propeller drawing a fluid through a Venturi nozzle. o (C) A reciprocating plunger directly applying force to a fluid. • (D) A rapidly moving stream of fluid passing through a nozzle.


44. In accordance with 33 CFR Subchapter O (Pollution), which type of Marine Sanitation Device (MSD) is used solely for the storage of sewage and flush water at ambient air pressure and temperature?

o (A) Type I o (B) Type II • (C) Type III o (D) Type IV


45. In an electro-hydraulic steering system, damage due to rudder shock is prevented by __________.

o (A) buffer springs • (B) relief valves o (C) oil flowing through the pumps o (D) dashpots


46. Which of the following statements is true concerning the operation of the device shown in the illustration? Illustration GS-0116

o (A) Item "I" moves as the rudder stock rotates. • (B) Item "N" moves as the rudder stock rotates. o (C) Both item "I" and item "N" move as the rudder stock rotates. o (D) Neither item "I" nor item "N" move as the rudder stock rotates.


47. The action necessary to use the steering gear room trick wheel when transferring the steering control from the wheelhouse to local control is to __________.

• (A) align the trick wheel to the rudder angle position before engaging o (B) set the six-way control valve in the trick wheel position o (C) open the power transfer switch before engaging the trick wheel o (D) always place the rudder in the amidships position to engage the trick wheel



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Q624 General Subjects U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 21 48. Overall heat transfer processes often involve two or more modes of heat transfer. Specifically, when

heat is being transferred from one side of an air compressor cylinder wall to the opposite side, what mode of heat transfer is associated with that particular part of the overall process?

• (A) Conduction o (B) Forced convection o (C) Natural convection o (D) Radiation


49. What statement represents the ideal gas law?

o (A) For a given mass of a gas, the volume is inversely proportional to its pressure and inversely proportional to its temperature.

o (B) For a given mass of a gas, the volume is directly proportional to its pressure and directly proportional to its temperature.

• (C) For a given mass of a gas, the volume is inversely proportional to its pressure and directly proportional to its temperature.

o (D) For a given mass of a gas, the volume is directly proportional to its pressure and inversely proportional to its temperature.


50. Referring to the illustrated diagram, what type of HVAC system is shown? Illustration RA-0043

o (A) A variable air volume system o (B) A terminal reheat system o (C) A single zone system • (D) A dual duct system


51. What statement is true concerning a one-pipe hydronic heating system?

o (A) Each heating coil inlet temperature is different, as the hot water inlet temperature to each heating coil progressively rises as the water passes through each successive series connected coil.

o (B) Each heating coil inlet temperature is identical, as the hot water inlet temperature to each heating coil progressively drops as the water passes through each successive series connected coil.

o (C) Each heating coil inlet temperature is identical, as the hot water inlet temperature to each heating coil progressively rises as the water passes through each successive series connected coil.

• (D) Each heating coil inlet temperature is different, as the hot water inlet temperature to each heating coil progressively drops as the water passes through each successive series connected coil.



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Q624 General Subjects U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 21 52. Before boring a blind tapered hole, a good shop practice to follow is to __________.

o (A) use a tapered reamer • (B) drill to the small diameter of the taper o (C) drill to the large diameter of the taper o (D) bore a straight hole


53. Which of the listed temperature sensors is made of heat-treated metallic oxides and generally has a negative coefficient of resistance?

o (A) Resistance temperature detector • (B) Thermistor o (C) Bimetallic device o (D) Thermocouple


54. What type of flow measuring device would measure totalized flow volume as opposed to an instantaneous flow rate?

o (A) Velocity flowmeter such as a turbine type • (B) Positive displacement meter, such as a nutating disk o (C) Variable area type, such as a rotameter o (D) Constriction type, differential head such as a venturi tube


55. The "tare weight" of a refrigerant storage cylinder refers to what weight?

o (A) the maximum weight of the refrigerant allowed o (B) the total weight of a fully charged cylinder • (C) the weight of an empty cylinder o (D) the weight of a cylinder and its current contents



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56. In attempting to start the hydraulic pump drive motor of a horizontal electro-hydraulic anchor windlass, what condition would prevent the electric motor from starting?

o (A) Failure to start could be the result of an electrical interlock associated with the wildcat clutches being disengaged.

• (B) Failure to start could be the result of an electrical interlock associated with the hydraulic pump stroke control being in other than the neutral position.

o (C) Failure to start could be the result of an electrical interlock associated with the hydraulic pump stroke control being in the neutral position.

o (D) Failure to start could be the result of an electrical interlock associated with handwheel operated wildcat band brakes being set.


57. As it pertains to the automatic hoist winch brake of an electro-hydraulic cargo-handling pedestal-type deck crane, what statement is true?

• (A) The brake is spring set and hydraulically released, and the brake automatically sets when the hoist pump is brought to zero stroke or there is a loss of servo power hydraulic pressure.

o (B) The brake is hydraulically set and spring released, and the brake automatically releases when the hoist pump is brought to zero stroke or there is a loss of servo power hydraulic pressure.

o (C) The brake is spring set and hydraulically released, and the brake automatically releases when the hoist pump is brought to zero stroke or there is a loss of servo power hydraulic pressure.

o (D) The brake is hydraulically set and spring released, and the brake automatically sets when the hoist pump is brought to zero stroke or there is a loss of servo power hydraulic pressure.


58. What is the pressure and condition of the refrigerant entering the receiver of a refrigeration system?

o (A) superheated high-pressure vapor o (B) subcooled low-pressure liquid • (C) subcooled high-pressure liquid o (D) superheated low-pressure vapor


59. The safety heads of most large reciprocating compressors used in refrigeration systems are held in place by what means?

o (A) discharge pressure in the relief valve return line o (B) tack welding on the sides o (C) large Teflon gaskets • (D) heavy coil springs



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Q624 General Subjects U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 21 60. If the discharge reed valves used in a refrigeration compressor are leaking badly, what statement is

true?

o (A) the low side pressure will indicate below normal • (B) the reed valve assemblies should be replaced o (C) the reed valves should be reground and relapped o (D) the high-pressure cut-out setting should be lowered


61. Leaking suction valves in a refrigeration compressor are indicated by which of the following?

o (A) lower than normal evaporator temperature o (B) lower than normal suction pressure o (C) noticeable increase in compressor noise • (D) higher than normal suction pressure


62. Which of the following illustrated thermal expansion valves would be appropriate to use on an evaporator coil with a 2 psi pressure drop, where externally adjustable superheat and a replaceable power element are both desired? Illustration RA-0006

o (A) A • (B) B o (C) C o (D) D


63. Thermostatic expansion valves come factory set with a certain value of superheat setting. When installing a new valve in the field, conditions may cause the actual superheat to deviate from the factory setting. Which statement about checking the setting a newly installed thermostatic expansion valve is correct?

o (A) No special tools are required as long as the solid state circuit control panels are functioning properly.

o (B) This procedure is done at the factory with tools not available to a mariner and may not be repeated in the field.

• (C) An accurate thermometer and a refrigeration type suction pressure gage are essential to this process.

o (D) The procedure requires a refrigeration wrench and a digital thermometer to measure box temperature.



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Q624 General Subjects U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 21 64. A high-pressure centrifugal chiller currently charged with R-134a is being evaluated for the need for

leak testing. Using the leak test procedures decision tree illustrated and the R-134a pressure-temperature chart illustrated, with the machine idle and the pressures equalized at 10 psig with an ambient temperature of 60°F, what statement is true? Illustration RA-0011 and RA-0047

o (A) The machine has a suspected leak; therefore nitrogen should be added to bring the pressure to 70 psig prior to checking for leaks.

• (B) The machine has a suspected leak; therefore the refrigerant pressure should be raised to 35 psig by adding refrigerant prior to checking for leaks.

o (C) The machine may or may not have a leak; therefore the machine should be checked for leaks without any adjustments in pressure.

o (D) The machine definitely does not have a leak; therefore no attempt at leak detection is necessary.


65. Which of the illustrated devices would be the LEAST accurate for the purposes of weighing-in a refrigerant charge? Illustration RA-0045

o (A) A o (B) B • (C) C o (D) D


66. Which of the following statements is true concerning the gauge labeled "A" of the illustrated gauge manifold set? Illustration RA-0001

o (A) The gauge labeled "A" is a standard pressure gauge and is usually color-coded blue. o (B) The gauge labeled "A" is a standard pressure gauge and is usually color-coded red. o (C) The gauge labeled "A" is a compound gauge and is usually color-coded red. • (D) The gauge labeled "A" is a compound gauge and is usually color-coded blue.


67. In a two-stage centrifugal air conditioning system such as the one illustrated, the liquid refrigerant passes from the condenser directly to what component? Illustration RA-0064

• (A) economizer o (B) expansion valve o (C) chiller o (D) evaporator



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68. Concerning the arrangement of equipment and associated hoses shown in the illustration, whatstatement is true? Illustration RA-0058

o (A) When recovering refrigerant from the centrifugal chiller using this method, the vent hoseconnection should be closed.

o (B) When recovering refrigerant from the centrifugal chiller using this method, it is possible toachieve the recovery levels required by law without any further recovery.

o (C) When recovering refrigerant from the centrifugal chiller using this method, it is permissible toexceed 90% of the weight capacity of the refrigerant drum.

• (D) When recovering refrigerant from the centrifugal chiller using this method, it minimizes the riskof chiller tube freeze-up.


69. In an air conditioning system set up as shown in the illustration, as the room humidistat initiates thelowering of the humidity of the conditioned supply air to a space, the actual process is accomplishedby what means? Illustration RA-0009

• (A) lowering the cooling coil temperature and raising the reheater temperatureo (B) raising the cooling coil temperature and lowering the reheater temperatureo (C) lowering both the cooling coil temperature and the reheater temperatureo (D) raising both the cooling coil temperature and the reheater temperature


70. If a reverse osmosis fresh water generator has fouled membrane modules, what statement is true?

• (A) The feed pressure would be higher than normal and the pressure drop across the membranemodules would be higher than normal.

o (B) The feed pressure would be lower than normal and the pressure drop across the membranemodules would be lower than normal.

o (C) The feed pressure would be higher than normal and the pressure drop across the membranemodules would be lower than normal.

o (D) The feed pressure would be lower than normal and the pressure drop across the membranemodules would be higher than normal.



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National Maritime Center

Serving Our Nation’s Mariners

10/9/2018

EL-0095

Adapted for testing purposes only from HUNT, Modern Marine Engineer’s Manual, Volume II, 3rd Edition

Copyright © 2002 by Cornell Maritime Press, Inc.

Further reproduction prohibited without permission of 40



9/24/2018

GS-0036

Adapted for testing purposes only from FRENCH, Mechanical Drawing, Seventh Edition

Copyright © 1966 by the McGraw-Hill, Inc.

Further reproduction prohibited without permission of 40 Q624 General Subjects


9/24/2018

GS-0045

Adapted for testing purposes only from Les-Sonic Self Contained

Pressure/Temperature Regulators

Copyright © by Leslie Co.



9/24/2018

GS-0051

Adapted for testing purposes only from MOLLAND

The Maritime Engineering Reference Book

Copyright © 2008 by Elsevier Ltd.



5/29/2019

GS-0081

Adapted for testing purposes only from Engine Room Tools

Copyright © 1970 by School of Marine Engineering & Navigation

District 2 MEBA AFL-CIO, Safety & Education Plan



9/26/2018

GS-0111

Adapted for testing purposes only from DUDLEY, Gear Handbook

Copyright © 1962 by McGraw-Hill, Inc.



9/26/2018

GS-0116

Adapted for testing purposes only from HUNT, Modern Marine Engineer’s Manual, Volume II

Copyright © 2002 by Cornell Maritime Press, Inc.



9/27/2018

GS-0153

Adapted for testing purposes only from Operator, Unit and Direct Support Maintenance Manual

Including Repair Parts and Special Tools List for Oil Water Separator

TM 55-1925-285-13 & P




9/27/2018

GS-0156

Adapted for testing purposes only from D379, D398, D399 Service Manual

Copyright © Caterpillar Tractor Co.



9/27/2018

GS-0175

Adapted for testing purposes only from Heli-Sep Model 550/OCD Technical Manual

Copyright © by Coffin World Water Systems



10/22/2018

Adapted for testing purposes only from Instruction Manual for Freshwater Generator Type VSP-36-100/125 CC/SWC

Copyright © Alfa Laval Desalt

Further reproduction prohibited without permission

MO-0110




9/17/2018

RA-0006

Adapted for testing purposes only



9/17/2018

RA-0011

R-134a Pressure-Temperature Chart



Temperature °F

Vacuum “Hg

-40 14.6

-35 12.3

-30 9.7

-25 6.7

-20 3.5

-18 2.1

-16 0.6

Temperature °F

Pressure psig

-14 0.4

-12 1.2

-10 2.0

-8 2.9

-6 3.7

-4 4.6

-2 5.6

0 6.5

2 7.6

4 8.6

6 9.7

8 10.8

10 12.0

12 13.2

14 14.5

16 15.8

18 17.1

20 18.5

22 19.9

24 21.4

26 22.9

Temperature °F

Pressure psig

28 24.5

30 26.1

32 27.8

34 29.6

36 31.3

38 33.2

40 35.1

45 40.1

50 45.5

55 51.2

60 57.4

65 64.1

70 71.1

75 78.7

80 86.7

85 95.3

90 104.3

95 114.0

100 124.2

105 135.0

110 146.4

115 158.4

120 171.2

125 184.6

130 198.7

135 213.6

140 229.2

145 245.6

150 262.9

155 281.1




9/18/2018

RA-0045





9/17/2018

RA-0047 Leak Test Procedure for Idle Centrifugal Chiller Charged with R-134a Refrigerant

Adapted for testing purposes only from CARRIER, 19XRT Hermetic Centrifugal Liquid Chillers

Start-Up, Operation, and Maintenance Instructions

Copyright © 1998 by Carrier Corporation


Yes

No

No

Yes

Yes

Yes

No

No

Yes

Yes

No

No

Raise pressure to 70 psig with nitrogen, and if using electronic

leak detector add trace gas.

Locate and mark all leaks.

Release nitrogen pressure from machine

and repair all leaks.

Perform leak test using soap bubbles solution, ultrasonic or

electronic leak detector.

Perform standing vacuum test.

Evacuate machine.

Does vacuum hold?

Perform dehydration evacuation of machine.

Charge machine with refrigerant.

Are leaks detected?

Top-off refrigerant charge as necessary.

Record condenser and cooler pressures and ambient temperature

Does condenser pressure at saturation conditions correspond to ambient temperature and is cooler

pressure 15 psig or higher?

Leak not suspected; however, a minor or recently developed leak

may exist.



Power up controls to energize oil heater, and when oil is hot equalize condenser

and cooler pressures.

Locate and mark all leaks.

Perform refrigerant recovery and repair all leaks.

Are leaks detected?

Leak is suspected; may be major or the consequence of

long-term leakage.

Is either condenser or cooler pressure at

0 psig?

Power up controls to energize oil heater, and when oil is hot equalize condenser

and cooler pressures.

Add refrigerant until pressure is above 35 psig.



Are leaks detected?

Perform refrigerant recovery.


U.S.C.G. Merchant Marine Exam DDE – Unlimited HP Q624 ...Q624 General Subjects U.S.C.G. Merchant...

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