Free Red Seal Industrial Mechanic (Millwright) Examination Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Red Seal Industrial Mechanic (Millwright) Examination practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A millwright discovers that a small pile of magnesium machining chips is burning. For identifying suitable extinguishing equipment, which fire class describes the burning material?

   1. A.Class A
   2. B.Class B
   3. C.Class C
   4. D.Class DCorrect answer: D

   Explanation: CCOHS classifies this by the material involved: "Class D - Fires involving combustible metals such as magnesium, titanium, sodium, and potassium." The burning magnesium chips therefore form a Class D fire.

   Reference: CCOHS: Fire Extinguishers - Portable — What are the different classes of fires?

2. 2A millwright plans to hoist a machine weighing 4,500 kg with a 120 kg lifting beam and 180 kg of other suspended rigging. What total load must be considered when checking the hoist's capacity?

   1. A.4,500 kg
   2. B.4,620 kg
   3. C.4,680 kg
   4. D.4,800 kgCorrect answer: D

   Explanation: IHSA states that "the weight of hook blocks, hooks, slings, equalizer beams, and other parts of the lifting tackle" must be added to the load. The total is 4,500 + 120 + 180 = 4,800 kg. The other results omit both rigging components, omit the 180 kg, or omit the 120 kg, respectively.

   Reference: IHSA Construction Health and Safety Manual: Rigging — Determining Loads; Weight of tackle

3. 3A qualified worker is installing a reversible three-phase motor. Its initial phase connection is A-B-C, and the uncoupled motor turns opposite to the required direction. After isolating and locking out the supply, which phase sequence will reverse its rotation?

   1. A.A-B-C
   2. B.B-C-A
   3. C.C-A-B
   4. D.A-C-BCorrect answer: D

   Explanation: ABB says to "interchange any two of the three line leads for three phase motors" after disconnecting and locking out power. A-C-B exchanges B and C; B-C-A and C-A-B are cyclic shifts and preserve the original phase sequence, while A-B-C is unchanged.

   Reference: ABB/Baldor: Installation, Operation and Maintenance of AC Motors — Installation & Operation, Rotation

4. 4A fixed-displacement pump supplies 20 L/min at 300 rpm. During installation planning, its speed is increased to 450 rpm. Assuming negligible leakage, what flow should the millwright expect?

   1. A.10.0 L/min
   2. B.13.3 L/min
   3. C.30.0 L/minCorrect answer: C
   4. D.45.0 L/min

   Explanation: The U.S. Department of Energy says positive displacement pumps have a fixed displacement volume and "flow rates they generate are directly proportional to their speed." Thus 20 L/min × 450/300 = 30.0 L/min. The 10.0 L/min result applies only the speed increase, 13.3 L/min reverses the ratio, and 45.0 L/min incorrectly squares the ratio.

   Reference: U.S. Department of Energy, Improving Pumping System Performance — Section 1, Positive displacement pumps

5. 5A pneumatic installation uses a desiccant dryer. The inlet air contains suspended oil mist, and the millwright must protect the dryer bed from fouling. Which treatment component should be fitted immediately upstream?

   1. A.A particulate air filter
   2. B.A coalescing air filterCorrect answer: B
   3. C.An adsorbent air filter
   4. D.A membrane air dryer

   Explanation: The source says "coalescing filters to remove lubricant and moisture" and recommends a coalescing filter before a desiccant dryer to protect the bed. Particulate filters remove solids; adsorbent filters address tastes and odours; the described membrane dryer removes water vapour rather than the suspended oil mist.

   Reference: U.S. Department of Energy, Improving Compressed Air System Performance — Introduction to Industrial Compressed Air Systems, Compressed Air Filters

6. 6During field balancing, a tachometer views a reference mark on a shaft while vibration amplitude and phase are measured. Relative to which reference is the vibration phase recorded?

   1. A.The shaft's tachometer markCorrect answer: A
   2. B.The shaft's coupling centreline
   3. C.The shaft's bearing centreline
   4. D.The shaft's axial thrust face

   Explanation: Fluke explains that "The tach signal works like pendulum A in the illustrations shown in Figure 2, it serves as a zero point or datum." Trial weights are placed at known angles relative to the shaft marking that generates this signal; the other shaft features are not the datum in this setup.

   Reference: Fluke, Phase in Vibration Analysis: Theory, Applications, and Examples — Use of phase for balancing

7. 7A millwright needs a particulate filter for an oil-mist exposure over more than one eight-hour shift. The respiratory protection program permits reuse for that period, and each listed filter meets the required efficiency and fit. Which filter series is suitable for this duration in oil mist?

   1. A.N95 filter
   2. B.P95 filterCorrect answer: B
   3. C.N99 filter
   4. D.R95 filter

   Explanation: CCOHS states that "P series (Strongly resistant to oil) - May be used in any atmosphere, including those with oil particulates, for more than one shift." It also directs users to check the manufacturer's service life for oil exposure. N-series filters are not oil resistant, and R-series use in oil is limited to one shift.

   Reference: CCOHS: Respirators - Respirator Selection — What are the different classes of respirators?

8. 8Two identical solid steel plates, each 3 ft by 5 ft and 1/2 in thick, will be lifted together. Using the IHSA approximation of 40 lb per square foot for steel 1 in thick, what is the estimated combined weight of the plates?

   1. A.300 lb
   2. B.600 lbCorrect answer: B
   3. C.1,200 lb
   4. D.2,400 lb

   Explanation: IHSA gives the standard approximation "1 square foot of steel an inch thick will weigh about 40 pounds." The plates weigh 2 × 3 ft × 5 ft × 0.5 in × 40 lb/(ft²·in) = 600 lb. The other answers use one plate, count twice too many plates, or invert the thickness factor.

   Reference: IHSA Hoisting and Rigging Safety Manual — Determining Load Weights, Calculating weight, p. 13

9. 9While installing a motor, a millwright finds that one mounting foot has a measurable gap above its base before the bolts are tightened. What condition does this indicate?

   1. A.Rotor unbalance
   2. B.Soft footCorrect answer: B
   3. C.Shaft bow
   4. D.Thermal growth

   Explanation: The DOE sourcebook says "Soft foot refers to the gaps that develop between a motor’s mounting foot and the foundation." Rotor unbalance, shaft bow, and thermal growth describe different conditions.

   Reference: U.S. Department of Energy: Improving Motor and Drive System Performance — Performance Opportunity Road Map, Balance and Alignment Checks, p. 30

10. 10A centrifugal pump produces a crackling noise, and inspection shows impeller erosion. The measured local liquid pressure has fallen below its vapour pressure, so bubbles form and collapse as pressure rises. Which condition is occurring?

    1. A.Suction recirculation
    2. B.Pump cavitationCorrect answer: B
    3. C.Discharge recirculation
    4. D.Hydraulic water hammer

    Explanation: The source states that "Cavitation occurs when the static pressure in the pump drops below the vapor pressure of a fluid." Vapour bubbles form and collapse as pressure rises. Recirculation can also damage an impeller, but the stated vapour-pressure and bubble-collapse mechanism identifies cavitation; water hammer is a pressure transient.

    Reference: U.S. Department of Energy, Improving Pumping System Performance — Section 2, Centrifugal pumps, Cavitation