MODU – Assistant Engineer, Revision & Practice Exams

Casing drains may be required on a waste heat boiler gas passage side to __________.

1. prevent an accumulation of boiler water entering gas passages as a result of a pinhole tube leak
2. sample gases for testing
3. drain off condensation ✓
4. release excess pressure

The most common cause of scale formation in an auxiliary boiler is __________.

1. Improper treatment of the feedwater with calcium sulfate
2. Fuel oil in the feedwater
3. Concentrations of calcium sulfate in the boiler water ✓
4. Excessive feedwater alkalinity

A burning mattress is considered as which of the following classes of fire?

1. Class "A" ✓
2. Class "B"
3. Class "C"
4. Class "D"

Annual servicing of a hand portable CO2 fire extinguisher includes __________.

1. Weighing the cylinder and recharging if weight loss exceeds 10% of the weight of the charge ✓
2. Inspecting the pressure gauge to ensure the needle is within operating range
3. Hydrostatic testing of the cylinder
4. Discharging, cleaning inside, and recharging

According to 33 CFR Subchapter O (Pollution), an oceangoing ship of over 400 gross tons must be fitted with a standard discharge shore connection. What size bolt circle diameter is required for this shore connection to transfer oily ballast to a shoreside reception facility?

1. 125 mm
2. 183 mm ✓
3. 215 mm
4. 250 mm

In order to distribute the side pressures over a wide area of the cylinder walls and liners, which of the listed types of pistons are used in modern low-pressure air compressors?

1. Differential
2. Valve-in-head
3. Trunk ✓
4. Barrel

Which of the petroleum products listed has a flash point below 150°F?

1. Road oils
2. Light fuel oils ✓
3. Lubricating oils
4. Asphalt

The amount of HCFC-123 in a storage cylinder is measured by what means?

1. saturation temperature
2. weight ✓
3. saturation pressure
4. volume

The source of power for the CO2 discharge alarm siren is obtained from __________.

1. The flow of CO2 under pressure ✓
2. The emergency power and lighting bus
3. The general alarm 24-volt DC bus
4. All of the above

An oxygen indicator will detect __________.

1. concentrations of explosive gas
2. the presence of harmful amounts of carbon monoxide
3. an oxygen deficiency in a space ✓
4. all of the above

Contact with any energized electrical system conductor is potentially hazardous and precautions should be taken to prevent exposure. With all other factors considered equal (such as voltage, conducting path through the body and the duration of contact), contact with an energized electrical system conductor of which system type would produce the most damaging effect?

1. DC systems
2. 60 Hz AC systems ✓
3. 10 kHz AC systems
4. All the above systems would be equally as damaging

Diesel engine closed, re-circulating cooling water systems are particularly prone to cavitation corrosion/erosion. Which of the listed cooling system/engine components has surfaces in contact with the coolant that are most susceptible to this type of corrosion and erosion?

1. Engine exhaust cooling water jackets
2. Cylinder head cooling water passages
3. Wet-type cylinder liners ✓
4. Cylinder cooling water jackets

To prevent the spread of fire by convection you should __________.

1. remove combustibles from direct exposure
2. cool the bulkhead around the fire
3. shut off electrical power
4. close all openings to the area ✓

Which of the following statements is true concerning the fire extinguisher shown in the illustration? Illustration SF-0006

1. There is no danger of reflash in using the illustrated extinguisher on a class "B" fire.
2. The illustrated extinguisher must never be used in conjunction with water.
3. The initial discharge of the extinguisher should be at close range to scatter the burning material.
4. The agent may be applied in short bursts by squeezing and releasing the lever on the nozzle. ✓

Bunker "C" is classified as a grade __________.

1. "A" liquid
2. "B" liquid
3. "E" liquid ✓
4. "D" liquid

In the absence of external forces, the center of gravity of a floating vessel is located directly above the __________.

1. geometric center of the displaced volume ✓
2. center of flotation
3. metacenter
4. amidships

What is meant by the term emergency bilge suction?

1. The means by which the machinery space bilge is pumped out by a pump not normally used as a bilge pump and drawing a suction on the bilge through either bilge manifolds or automatic bilge suction valves.
2. The means by which the machinery space bilge is pumped out by a pump not normally used as a bilge pump and drawing a suction directly on the bilge independent of any bilge manifolds or automatic bilge suction valves. ✓
3. The means by which the machinery space bilge is pumped out by a pump normally used as a bilge pump and drawing a suction directly on the bilge independent of any bilge manifolds or automatic bilge suction valves.
4. The means by which the machinery space bilge is pumped out by a pump normally used as a bilge pump and drawing a suction on the bilge through either bilge manifolds or automatic bilge suction valves.

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

1. The hydro-pneumatic expansion tank is operating with an insufficient air charge. ✓
2. The hydro-pneumatic tank is operating with a low water level.
3. A low water level exists in the potable water storage tank.
4. Pump "A" wearing rings have excessive clearance.

As shown in figure "B" in the illustrated block diagram of a central operating system configured for supervisory control, what is the function of the block "ANALOG (A-D MUX)"? Illustration EL-0094

1. A high-speed solid-state switching device called a multiplexer capable of scanning a large number of digital sensors in a short period of time and converting these signals to analog values for processing by the CPU.
2. A low-speed solid-state switching device called a multiplexer capable of scanning a small number of digital sensors in a long period of time and converting these signals to analog values for processing by the CPU.
3. A low-speed solid-state switching device called a multiplexer capable of scanning a small number of analog sensors in a long period of time and converting these signals to digital values for processing by the CPU.
4. A high-speed solid-state switching device called a multiplexer capable of scanning a large number of analog sensors in a short period of time and converting these signals to digital values for processing by the CPU. ✓

A three inch overboard discharge line, located six feet below the waterline, has ruptured and separated from the hull. What would be the minimum number of strokes per minute required from a 10" x 8" x 12" duplex double acting steam operated reciprocating bilge pump, operating at 96% efficiency, to keep the bilge water level from continuing to rise? (231 cu in = 1 gal) Illustration SF-0034

1. 45 strokes per minute
2. 56 strokes per minute
3. 87 strokes per minute ✓
4. 98 strokes per minute

Which of the conditions listed is necessary for a substance to burn?

1. The temperature of the substance must be equal to or above its fire point
2. The air must contain oxygen in sufficient quantity
3. The mixture of vapors with air must be between the LEL and the UEL
4. All of the above ✓

Which segment of the two-stroke cycle engine diagram shown in the illustration represents the exhaust event? Illustration MO-0037

1. I
2. II
3. III
4. IV ✓

Starting air check valves are held firmly on their seats by __________.

1. cam rollers on the camshaft
2. spring force ✓
3. air pressure on top of the valve differential piston
4. air pressure on the bottom of the valve differential piston

The ignition quality of diesel fuel becomes LESS critical as __________.

1. lube oil additives are increased
2. designed piston speeds are increased
3. designed injection pressures are decreased
4. designed engine speeds are decreased ✓

The unit of measure expressed as centistokes (cSt) is a measure of what fuel property?

1. Viscosity ✓
2. Heating value
3. Density
4. Cetane rating

The instrument shown in the illustration would be used on a diesel engine to __________. Illustration MO- 0031

1. Measure exhaust gas pressure
2. Measure cylinder compression or firing pressures ✓
3. Measure concentration of chromate in jacket water
4. Balance exhaust gas temperature readings

What prevents the thrust bearing blocks shown in the illustration from rotating within the housing? Illustration MO-0120

1. Found within the thrust bearing cap or cover are extended protrusions to position the thrust shoe segments and maintain minimum clearance. ✓
2. The bearing blocks are massive and their weight provides sufficient force to prevent rotation.
3. The thrust shoes are dovetailed into the collar.
4. The bearing assembly is specifically designed to allow for rotation, permitting the transmittal of axial forces across a greater surface area and minimizing loading densities.

The water in an auxiliary boiler should be tested for chloride content to determine __________.

1. Total dissolved solids
2. Water hardness
3. Salt contamination ✓
4. Chlorine contamination

If a diesel engine has been stopped because of piston seizure due to severe overheating, the crankcase __________.

1. Scavenge pump should be immediately secured to prevent loss of lube oil
2. Ventilation system should be continued in operation for one hour for cooling
3. Inspection covers should not be opened until the engine has cooled ✓
4. Explosion covers should be opened slightly to provide extra ventilation

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 the functional purpose of the Zener diode "CR1" as shown in section "D" of the regulated DC power supply? Illustration EL-0085

1. aids in output voltage regulation ✓
2. is a temperature compensator
3. corrects power factor
4. prevents excessive currents

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.

What is the normal direction of flow through the device shown in the illustration while operating in the processing mode? Illustration GS-0153

1. The oily-water mixture enters through the pressure control valve "2" and exits with the processed liquid through valve "14".
2. The oily-water mixture enters through valve "4" and exits as processed liquid through valve "14".
3. The oily-water mixture enters through valve "5" and exits the separator through valve "14" as processed liquid. ✓
4. The oily-water mixture enters through valve "14" and exits with the processed liquid through valve "4".

Referring to the illustrated huddling-chamber safety valve, what statement concerning the blowdown adjusting ring (B) is true? Illustration SG-0018

1. Raising the blowdown adjusting ring further increases the area of exposure to pressure after the valve pops and as a result, the valve blowdown will increase. ✓
2. Raising the blowdown adjusting ring further decreases the area of exposure to pressure after the valve pops and as a result, the valve blowdown will decrease.
3. Raising the blowdown adjusting ring further increases the area of exposure to pressure after the valve pops and as a result, the valve blowdown will decrease.
4. Raising the blowdown adjusting ring further decreases the area of exposure to pressure after the valve pops and as a result, the valve blowdown will increase.