QMED, Revision & Practice Exams

Why can CFC or HCFC refrigerants leaking into a confined space or in limited surroundings cause suffocation?

1. Refrigerants lighter than air will rise.
2. Refrigerants are heavier than air and displace oxygen. ✓
3. Refrigerants contain an acidic substance.
4. Refrigerants obnoxious odor prevents breathing.

In general, the thermal bulb for a thermal expansion valve used in a reciprocating air conditioning system is usually charged with what substance?

1. bees wax
2. distilled water
3. the same refrigerant as the system ✓
4. mercuric sulfate

A low velocity fog applicator is held in an all-purpose nozzle by a bayonet joint. The applicator is prevented from rotating in the joint by __________.

1. a keeper screw
2. a locknut
3. water pressure
4. a spring-loaded catch ✓

Why is it essential to introduce CO2 from a fixed fire extinguishing system, into a large engine room, as quickly as possible?

1. The fire may warp the CO2 piping.
2. To keep the fire from spreading through the bulkheads.
3. Carbon dioxide takes a long time to disperse to all portions of a space.
4. Updraft from the fire tends to carry the CO2 away. ✓

Under what circumstance would a hand-held portable phase sequence indicator be used should the main switchboard mounted fixed phase sequence indicator be inoperative?

1. paralleling alternators
2. replacing a defective solenoid
3. installing a new synchroscope
4. preparing to make the shore power connection ✓

Where is the air charge for an air starting system stored?

1. Air compressor
2. Pressurized tank ✓
3. Distributor assembly
4. Cylinder check valve

Whether using a centrifuge or a simple filter, oil cleaning and filtration will be the most effective when the oil is at a __________.

1. high temperature and a high viscosity
2. high temperature and a low viscosity ✓
3. low temperature and a high viscosity
4. low temperature and a low viscosity

A naturally aspirated diesel engine at full throttle will have an intake manifold pressure __________.

1. slightly less than atmospheric pressure ✓
2. constantly decreasing as engine load increases
3. approximately equal to exhaust manifold pressure at all times
4. that is widely fluctuating

In a diesel engine jacket water cooler, with sea water cooling the fresh water, the __________.

1. Jacket water pressure must always be less than the sea water pressure
2. Sea water temperature must never be warmer than 40°F
3. Jacket water temperature must always be less than 60°F
4. Jacket water pressure should always be greater than the sea water pressure ✓

Which of the following conditions represents a particular advantage of using a positive pressure type self- contained breathing apparatus in an atmosphere that is immediately dangerous to life or health?

1. The positive pressure in the facepiece prevents contaminated air from entering the facepiece. ✓
2. The average operating time for most air cylinders is over an hour.
3. The equipment is compact and the wearer can work in confined spaces without difficulty.
4. The equipment used is lightweight and easy to wear by reducing physical strain on the wearer.

When required to work in an area where explosive gases may accumulate, you should use hand tools which are __________.

1. approved by the Coast Guard
2. high carbon steel
3. non-ferrous ✓
4. fixed with a ferrous cover

The advantage of using a dry chemical fire extinguishing agent is __________.

1. permanent extinguishment regardless of the reignition sources
2. its good stability and non-toxicity ✓
3. its excellent cooling ability
4. all of the above

A hand portable CO2 fire extinguisher is effective on burning oil only __________.

1. To prevent rekindling
2. If applied promptly ✓
3. If applied in connection with foam
4. If attempts to extinguish the fire with low velocity fog have failed

High concentrations of hydrogen sulfide gas are most dangerous to personnel because they can __________.

1. cause involuntary skeletal muscle contractions
2. paralyze your breathing system ✓
3. cause eye inflammation
4. cause dizziness

Which of the listed types of seals is used effectively for pumps handling toxic or highly flammable liquids that cannot be permitted to escape into the atmosphere?

1. Conventional stuffing box
2. Double mechanical seal ✓
3. External mechanical seal
4. Rubber bellows mechanical seal

If the speed of a drill is too great, the drill will __________.

1. not cut
2. rapidly dull ✓
3. cut slower
4. cut faster

The multiplier prefix "giga" (G) such as used in "gigabytes" represents what multiplication factor?

1. thousand (10 to the 3rd power)
2. million (10 to the 6th power)
3. billion (10 to the 9th power) ✓
4. trillion (10 to the 12th power)

What is a useful instrument for checking 3-phase AC motor performance by measuring possible unbalanced currents?

1. vibrating-reed frequency meter
2. clamp-on ammeter ✓
3. D'Arsonval iron-vane probe
4. hand or battery-operated megger

Which of the following voltage testers would be associated with high quality, be safe to use, and minimize the electric shock hazard?

1. a voltage tester with a high input impedance and a voltage rating higher than any expected measured voltages ✓
2. a voltage tester with a high input impedance and a lower voltage rating than any expected measured voltages
3. a voltage tester with a low input impedance and a higher voltage rating than any expected measured voltages
4. a voltage tester with a low input impedance and a lower voltage rating than any expected measured voltages

Which characteristic of fuel oil is the most significant when determining the temperature to which the fuel oil must be heated for proper atomization?

1. Specific gravity
2. Flash point
3. Pour point
4. Viscosity ✓

Which of the following procedures represents the proper care of unused burners during low load conditions?

1. They should be removed, cleaned, refitted with smaller tips and reinstalled to be ready for immediate use.
2. They may be left in place, but only if they are clean and if fuel oil is recirculated to provide cooling.
3. They may be left in place, with fuel and steam secured as long as they are not fouled.
4. They should be removed, cleaned and stored in the rack on the burner bench. ✓

Which of the following statements describes the characteristics of precision manufactured roller bearings?

1. They have a relatively high power loss due to friction.
2. They are well adapted to variable speed operation. ✓
3. Their lubrication is complicated and requires constant attention.
4. They are not capable of maintaining alignment over long periods of time.

It is necessary to cool the bulkheads and decks surrounding a compartment where there is a fire in order to __________.

1. cool the metal below its ignition temperature
2. form a dense coating of smothering steam
3. prevent oxygen from reaching the flames
4. prevent the fire from spreading by the conduction of heat ✓

Which of the following procedures reduces the possibility of an interior ventilation duct fire from rapidly spreading?

1. Having a portable CO2 ready at each duct opening.
2. Keeping the duct exterior clean.
3. Having a fire hose charged at each duct opening.
4. Keeping the duct interior clean. ✓

Under normal conditions, the rate of heat transfer in a feedwater heater is most greatly affected by the __________.

1. pH of the feedwater
2. temperature differential between the steam and feedwater ✓
3. density of the feedwater
4. speed of the main feed pump

Which of the following conditions is indicated by oil flowing through a lube oil gravity tank overflow sight glass?

1. Sufficient oil flow is being supplied to the gravity tank. ✓
2. Excessive oil is stored in the gravity tank.
3. Turbine bearing failure has occurred.
4. Insufficient oil is being pumped to the gravity tank.

With regard to the number of passes through the tubes of shell-and-tube heat exchangers, what statement is true?

1. In two-pass and four-pass heat exchangers, the inlet and outlet tube-side fluid connections are at the same end. ✓
2. In single-pass and two-pass heat exchangers, the inlet and outlet tube-side fluid connections are at the same end.
3. In single-pass and two-pass heat exchangers, the inlet and outlet tube-side fluid connections are at opposite ends.
4. In two-pass and four-pass heat exchangers, the inlet and outlet tube-side fluid connections are at opposite ends.

Mechanical shaft seals used on water service pumps require lubrication of the seal faces to minimize deposits of foreign matter on those surfaces. Which of the following pressures and lubricants are required?

1. Oil under positive pressure.
2. Water under negative pressure.
3. Water under positive pressure. ✓
4. Oil under negative pressure.

To prevent overheating and scoring of the shaft after repacking the stuffing box, which of the following procedures should be carried out?

1. Lubricate the lantern ring with cylinder oil before installing new turns of packing.
2. Tightening the gland in all the way and then backing it off slightly.
3. Operating the pump slowly and applying oil freely to the shaft until the packing is properly seated.
4. Tighten the packing in small increments while the pump is operating. ✓

Which of the drill sets listed would commonly be referred to as a “Jobbers Set”?

1. A set of numbered size drills from 1 to 60.
2. A set of fractional size drills from 1/16'' to 1/2''. ✓
3. A set of fractional size drills from 1/2'' to 2''.
4. A set of lettered size drills from A to Z.

On a ship with a continuously manned engine room, with a three-person watch rotation, what is the watch and rest period rotation?

1. 4 hours on watch followed by 8 hours rest ✓
2. 6 hours on watch followed by 6 hours rest
3. 8 hours on watch followed by 4 hours rest
4. 8 hours on watch followed by 8 hours rest

In a refrigeration system, what component is installed directly downstream of the thermal expansion valve?

1. box solenoid valve
2. compressor
3. evaporator coil ✓
4. receiver

The bypass valve on a self-contained breathing apparatus (SCBA) bypasses __________.

1. the regulator in an emergency ✓
2. oxygen to the atmosphere
3. the regenerator in an emergency
4. a breathing bag containing excessive pressure

Kapok life jackets require proper care and should NOT be __________.

1. used as seats, pillows, or footrests
2. left on open decks
3. stowed near open flame or where smoking is permitted
4. all of the above ✓

Which fire extinguisher is most prone to freezing when stowed in low temperatures?

1. Foam ✓
2. Carbon dioxide
3. Halon 1211
4. Dry chemical

Which of the following statements concerning fire-tube boilers is correct?

1. Combustion gases flow through the tubes. ✓
2. Flames impinge on the tubes.
3. Combustion occurs in the tubes.
4. Water flows through the tubes.

Of the many impurities commonly found in marine lubricating oil, which of the following CANNOT be removed by a centrifugal purifier at normal operating speeds and temperatures?

1. Metal particles
2. Water
3. Diesel fuel oil ✓
4. Carbon particles

What information can be obtained from a marine chemist's certificate on a tank barge?

1. The tanks which are safe to enter when the certificate was issued. ✓
2. The number of fire extinguishers required onboard.
3. The quality of the barge's cargo.
4. The barge's stability information.

When troubleshooting a lead-acid storage battery, what is the best method for detecting a weak or dead cell?

1. visually inspecting the electrolyte levels of each cell
2. comparing the specific gravity of the electrolyte in each cell ✓
3. taking an open circuit voltage test of individual cells
4. taking each cell's temperature with a calibrated mercury thermometer

What is the characteristic of a wound-rotor induction motor, with a high resistance inserted in series with the rotor winding at startup?

1. relatively high starting torque and high stator current
2. relatively low starting torque and high stator current
3. relatively low starting torque and low stator current
4. relatively high starting torque and low stator current ✓

Which of the following statements is correct concerning heat transfer?

1. Heat is given off from a high temperature region known as a heat sink.
2. Heat transfer rate is affected most by the size of the heat sink involved.
3. Heat transfer rate is affected most by the temperature difference between the heat source and the heat sink. ✓
4. Heat transfer by radiation will occur only by mass motion of a fluid substance.

By which of the listed methods may heat be transferred from one body to another?

1. Radiation
2. Convection
3. Conduction
4. All of the above. ✓

Progressive flooding in the engine room may be minimized by securing watertight boundaries and __________.

1. dumping fuel oil
2. transferring reserve feedwater
3. evacuating the engine room
4. pumping out flooded compartments ✓

At a minimum threshold, how many milliamps of current through the body produces a painful sensation that most people would perceive as an electric shock?

1. 3 to 7 mA ✓
2. 10 to 16 mA
3. 30 mA
4. 100 mA for 2.5 sec.

The gas that exists in the stratosphere forming a protective shield that helps to protect the environment from the harmful effects of ultraviolet radiation is called what?

1. radon
2. ozone ✓
3. nitrogen
4. oxygen

The state of charge of a stored pressure type dry chemical fire extinguisher can be readily determined by __________.

1. weighing the CO2 cartridge
2. weighing the cylinder
3. visual inspection of the pressure gage ✓
4. removing the lid and checking the level of dry chemical

You notice smoke coming from an open laundry room doorway, which smells like electrical insulation. After activating the fire alarm, which of the following would be the lowest action priority?

1. Close the door to the room.
2. Locate the nearest CO2 or dry chemical extinguisher.
3. Secure power to the washers and dryers.
4. Break out the nearest fire hose. ✓

Small oil spills on deck can be prevented from contaminating any waters by __________.

1. regularly emptying all drip pans
2. thoroughly draining all bunkering hoses
3. placing floating booms around the ship
4. plugging all scuppers and drains ✓

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?

1. Sea water flows through the shells of both the lube oil and jacket water coolers.
2. Sea water flows through the tubes of the lube oil cooler and through the shell of the jacket water cooler.
3. Sea water flows through the tubes of both the lube oil and jacket water coolers. ✓
4. Sea water flows through the tubes of the jacket water cooler and through the shell of the lube oil cooler.

Concerning the proper installation of the sensing bulb of a thermal expansion valve that is attached to the evaporator tail coil on a horizontal run, what statement is true?

1. the bulb should be attached so that the pinched off tubing should be oriented to one side and the capillary tube running to the valve diaphragm should be oriented to the opposite side
2. the bulb should be attached with no regard to the orientation of the pinched off tubing or the capillary tube running to the valve diaphragm
3. the bulb should be attached so that the pinched off tubing should be oriented down and the capillary tube running to the valve diaphragm should be oriented up ✓
4. the bulb should be attached so that the pinched off tubing should be oriented up and the capillary tube running to the valve diaphragm should be oriented down

The purpose of try-cocks used on an auxiliary boiler is to __________.

1. provide an alternate means of determining the water level, if the gage glass fails ✓
2. provide a means of adding chemical feed to the boiler water
3. provide a means for blowing down the gage glass
4. act as a steam sentinel valve, if any of the fusible plugs should melt

Through which of the listed processes is sufficient heat produced to cause spontaneous ignition?

1. Aeration
2. Anaerobic decomposition
3. Putrefaction
4. Oxidation ✓

Which of the following methods will reduce the possibility of producing an electrical spark?

1. Using a cargo hose with a built-in electrical bonding wire.
2. Connecting a bonding wire between the shoreside piping and the vessel.
3. Placing an insulating flange or a section of non-conducting hose in the hose setup.
4. All of the above. ✓

When opening or closing compressor service and line isolation valves on a typical refrigeration system that is fitted with packed valves, what must you do?

1. you must first remove the stem seal cap ✓
2. you should replace the gasket each time the valve position is changed
3. you should turn valves slowly to avoid thermal stresses due to low temperatures
4. you should never loosen or tighten the packing gland

What is an engine room bilge oily-water separator designed to do?

1. Remove small amounts of water from small amounts of oil.
2. Remove small amounts of water from large amounts of oil.
3. Remove small amounts of oil from large amounts of water. ✓
4. Remove small amounts of oil from small amounts of water.

Which of the instruments listed is used to measure the gauge of a piece of sheet metal?

1. Circular mil
2. Gauge calibrator
3. Wire gauge ✓
4. Inside micrometer

If a fire broke out in an automation console, you would first secure the power and then proceed to use which of the listed hand portable fire extinguishers?

1. CO2 ✓
2. Dry chemical
3. Soda acid
4. Foam

The most common type of containment device for spilled oil on the water is the use of __________.

1. booms ✓
2. straw
3. skimmers
4. chemical dispersants

The cubic inch (or liter) displacement of a cylinder is determined by the diameter of the piston and the __________.

1. length of the crankshaft
2. volume of the clearance space
3. weight of the piston
4. length of the stroke ✓

Which of the components listed prevents water from flowing back into the auxiliary exhaust line if the deaerating feed tank becomes flooded?

1. Exhaust piping
2. Check valve ✓
3. Pumps
4. Reverse-acting relief valve

What is the function of the intake system for a diesel engine?

1. The intake system's function is to ensure an adequate supply of clean air to support engine combustion and scavenging. ✓
2. The intake system's function is to ensure an adequate supply of clean lubricating oil to support engine lubrication.
3. The intake system's function is to ensure an adequate supply of clean sea water to support engine cooling.
4. The intake system's function is to ensure an adequate supply of clean air to support engine crankcase ventilation.

One function of the air receiver in a compressed air system is to __________.

1. minimize the system's line pulsations ✓
2. dry the air discharged from the intercooler
3. receive exhaust air from pneumatic accessories
4. remove all traces of oil from the air

In order for microbiological growths to thrive in a fuel tank it is necessary for __________.

1. vanadium to be present
2. low temperatures to exist
3. moisture or water to be present ✓
4. electrolysis to be occurring

Moisture is removed from recovered refrigerant using a recycling machine by what means?

1. purging non-condensables off the top of the recovery cylinder
2. condensing the moisture in the condenser
3. opening a drain petcock on the oil separator
4. circulating the refrigerant through a dehydrator ✓

The term "oil foaming" in refrigeration practice, is used to describe what event?

1. release of miscible refrigerant from the lubricant in the crankcase ✓
2. sudden evaporation of entrapped air from the refrigerant liquid
3. release of dissolved lubricant from the refrigerant in the crankcase
4. sudden evaporation of entrapped moisture from the crankcase lubricant

In what application is an emergency shutdown most likely to be located outside the machinery space when the pump itself is located within the machinery space?

1. Lube oil circulating pump
2. Steering pump
3. Fuel oil transfer pump ✓
4. Fire pump

After extinguishing a paint locker fire using the fixed CO2 system, the next immediate action is for the space to be _________.

1. opened and doused with water to prevent reflash
2. opened and burned material removed
3. left closed with ventilation off until all boundaries are cool ✓
4. checked for the proper oxygen level

A definite advantage in the use of water as a fire extinguishing agent is its ability to __________.

1. rapidly contract as water is converted from a liquid to a vapor
2. vaporize and rapidly expand as water absorbs heat ✓
3. alternate expansion and contraction as water in liquid state becomes vapor
4. absorb smoke and gases as water is converted from liquid to vapor

What is the alarm signal for manning boat stations or boat drills onboard a merchant ship?

1. Continuous blast of the whistle for not less than 10 seconds supplemented by the continuous ringing of the general alarm bells for not less than 10 seconds.
2. Continuous blast of the whistle for not less than 3 seconds supplemented by the continuous ringing of the general alarm bells for not less than 3 seconds.
3. General alarm sounded 3 times supplemented by 3 short blasts of the whistle.
4. A succession of more than 6 short blasts followed by 1 long blast of the whistle supplemented by a comparable signal on the general alarm. ✓

What happens to the current in a series circuit when the voltage remains constant and the resistance increases?

1. remains the same
2. increases by the square
3. decreases ✓
4. increases

How can the loss of residual magnetism in an alternator or generator be corrected?

1. using a storage battery or battery charger to 'flash' the field ✓
2. running the generator at normal speed with the field rheostat fully counterclockwise
3. running the rotor in the opposite direction for 5 minutes
4. allowing the generator to run at 10% of normal speed for 5 minutes

In performing routine maintenance of a ship's service alternator, what should be included?

1. megger testing of all rectifying diodes
2. lubricating exciter slip rings
3. periodic cleaning of the air filters or screens ✓
4. changing the pedestal bearing insulation yearly

What type of eye protection affords the best protection from dust and airborne abrasives?

1. Side-shielded safety glasses
2. Full-face shield
3. Standard safety glasses
4. Eyecup safety goggles ✓

In a compression type automatic grease cup, the lubricant is forced into the bearing by __________.

1. a pressure gun
2. gravity flow
3. a Zerk fitting
4. spring force ✓

Which of the listed devices would be installed in the air compressor discharge line between the compressor and receiver of a control air system?

1. P-I converter
2. Moisture separator ✓
3. Lubricator
4. Vacuum breaker

At a minimum threshold, how many milliamps of current through the body produces a condition where most people would suffer ventricular fibrillation and could only be resuscitated with a ventricular defibrillator?

1. 3 to 7 mA
2. 10 to 16 mA
3. 30 mA
4. 75 mA for 5 sec. ✓

If the compressor is heard to knock while pumping down the low side for repairs, but otherwise the compressor sounds normal, this is a possible indication of what condition?

1. worn piston rings
2. faulty bearings
3. air being introduced to the system
4. foaming of the crankcase oil ✓

When purging a refrigeration gauge manifold using system pressure as the source of refrigerant for purging, which of the fittings listed is normally tightened LAST?

1. the low-pressure hose fitting at the gage manifold low-pressure connection
2. the high-pressure hose fitting at the discharge service valve service port
3. the high-pressure hose fitting at the gage manifold high-pressure connection
4. the low-pressure hose fitting at the suction service valve service port ✓

When the relief valve opens on a refrigeration compressor discharge line, it discharges high-pressure refrigerant vapor to what location?

1. refrigerant inlet of the condenser
2. inlet side of the evaporator
3. suction side of the compressor ✓
4. liquid strainer

To find the relative humidity of an accommodation space, you would use a __________.

1. Entropy Chart
2. Enthalpy Chart
3. Mollier Chart
4. Psychrometric Chart ✓

Remote valve operators are frequently fitted with a handwheel for local operation if the motor fails. If this is so, what is the procedure for local manual control?

1. Just rotate the handwheel in the appropriate direction for valve operation.
2. First move the lever to disengage the motor clutch, then rotate the handwheel. ✓
3. Motor-operated valves are generally not fitted with local handwheels.
4. First move the lever to engage the motor clutch, then rotate the handwheel.

Which of the precautions listed should be taken before opening any part of a refrigeration system for the purpose of accomplishing non-major repairs?

1. Set the high-pressure cut-out on manual to prevent automatic starting.
2. Bring the part of the system to be opened to 0 psig. ✓
3. Use the hot gas defrost line to remove any frost on the evaporator coils.
4. Bring the part of the system to be opened to a pressure corresponding to the ambient temperature.

Heat exchangers are most commonly found in a small auxiliary diesel engine __________.

1. governing system
2. fuel oil system
3. air starting system
4. lube oil system ✓

What would be the primary indication that a heavy fuel oil purifier supply pump suction strainer needed cleaning?

1. An increased pressure drop across the strainer (more differential). ✓
2. A drop in purifier bowl speed.
3. An increase in fuel oil supply temperature to the bowl.
4. A decreased pressure drop across the strainer (less differential).

Concerning the classification of steam turbines, a cross compound designed unit __________.

1. consists of a high-pressure turbine, crossover pipe, and low-pressure turbine ✓
2. consists of one Curtis stage and reaction blading
3. consists of reaction stages and a dummy piston
4. is made up of a varied assortment of impulse and reaction staging

Which of the following automatically actuates the overspeed tripping device installed on an auxiliary turbine?

1. centrifugal force ✓
2. pneumatic force
3. high back pressure
4. hydraulic pressure

Which of the following methods is used to lubricate main propulsion turbine reduction gears?

1. Oil is pressure fed through internal drilled passages which force oil to the gear's periphery.
2. Oil rings in channels outside the gears dip into oil in the sump and carry it to the gear teeth.
3. Oil is sprayed through nozzles at the point of gear mesh. ✓
4. The gears run through an open oil sump and oil is carried along on the gear teeth.