Free SOPEEC Fourth Class Power Engineer’s Certificate of Competency Examination — Part B (4B) Practice Questions

Sample Practice Questions

Try these 10 sample questions from the SOPEEC Fourth Class Power Engineer’s Certificate of Competency Examination — Part B (4B) practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A turbine lubrication specification calls for an additive that holds deposit-forming material suspended in the oil. Which additive provides this function?

   1. A.Detergent-dispersantsCorrect answer: A
   2. B.Anti-oxidants
   3. C.Antifoam additives
   4. D.Pour point depressants

   Explanation: The textbook states, "Detergent-dispersants will act to keep deposit-forming substances in suspension in the oil." Dispersants retain contamination in suspension. The other additive families control oxidation, foam and low-temperature flow.

   Reference: Power Engineering, Fourth Class, Part B, Unit B-1 — Chapter 1, Lubricating Oil Additives

2. 2A centrifugal pump develops a gravel-like noise after its inlet pressure falls below the liquid's vapour pressure. What is occurring inside the pump?

   1. A.Vapour bubbles form and collapse in higher-pressure regions.Correct answer: A
   2. B.Entrained air remains trapped at the highest casing point.
   3. C.Discharge liquid recirculates through enlarged wear-ring clearances.
   4. D.Liquid recirculates through the impeller at insufficient delivery flow.

   Explanation: The textbook states, "When the pressure, at any point inside a centrifugal pump, drops below the vapour pressure that corresponds to the temperature of the liquid, the liquid will vaporize and form bubbles. These bubbles are carried along with the flow until they reach a region of higher pressure, where they collapse and produce a shock wave." The given pressure condition identifies vapour formation and collapse. Trapped air, wear-ring leakage and low-flow recirculation are different pump problems.

   Reference: Power Engineering, Fourth Class, Part B, Unit B-2: Pumps and Compressors — Ch.1, Cavitation

3. 3During a controlled safety-valve test, the valve opens at 1200 kPa and reseats at 1120 kPa. What is its blowdown?

   1. A.80 kPaCorrect answer: A
   2. B.1120 kPa
   3. C.1200 kPa
   4. D.2320 kPa

   Explanation: The textbook states, "the blowdown is determined by subtracting the closing pressure from the opening pressure." Blowdown = 1200 − 1120 = 80 kPa. The other values use closing pressure, opening pressure, or their sum instead of the difference.

   Reference: Power Engineering, Fourth Class, Part B, Unit B-4 — Ch.4, Evaluating Safety Valve Performance

4. 4An operator chooses a hacksaw blade for thin metal stock. According to the stated good practice, what is the minimum number of teeth that should be cutting at one time?

   1. A.One tooth
   2. B.Two teeth
   3. C.Three teethCorrect answer: C
   4. D.Four teeth

   Explanation: The textbook states, "Good practice dictates at least three teeth should be cutting at any one time" Three is the minimum specified. Four may also maintain engagement, but the question asks for the minimum, not any acceptable greater number.

   Reference: Power Engineering, Fourth Class, Part B, Unit B-5 — Chapter 1, Hacksaws

5. 5In a sodium-cycle ion-exchange softener supplying boiler make-up, which ions replace the calcium and magnesium removed from the water?

   1. A.Hydrogen ions
   2. B.Sodium ionsCorrect answer: B
   3. C.Chloride ions
   4. D.Hydroxide ions

   Explanation: The textbook states, "In an ion exchange softener, scale-forming magnesium and calcium ions are replaced with ones that do not produce scale (usually sodium, Na+)." Sodium-cycle softening exchanges hardness cations for sodium. Hydrogen belongs to hydrogen-cycle exchange; chloride and hydroxide are anions.

   Reference: Power Engineering, Fourth Class, Part B, Unit B-6 — Ch.1, Sodium Zeolite System

6. 6In a reciprocating steam engine, admission is cut off before the piston reaches the end of its power stroke. What process allows steam already in the cylinder to continue doing work?

   1. A.Expansion of the trapped steamCorrect answer: A
   2. B.Compression of the trapped steam
   3. C.Evaporation of water in the cylinder
   4. D.Condensation of steam on the piston

   Explanation: The textbook states, "the admission of steam stops before the end of the stroke, to allow work to be done by steam expansion." Steam expands after admission cut-off. Compression requires work input; the cited engine stroke is not driven by in-cylinder evaporation or condensation.

   Reference: Power Engineering, Fourth Class, Part B, Unit B-7 — Ch.1, Steam Engine Construction

7. 7A luminaire contains two lamps producing 1500 lm each. Each lamp consumes 20 W and the ballast consumes 10 W. What is the luminaire's efficacy, including ballast consumption?

   1. A.30 lm/W
   2. B.60 lm/WCorrect answer: B
   3. C.75 lm/W
   4. D.150 lm/W

   Explanation: The textbook states, "Efficacy, then, is expressed in lumens per watt." Total flux = 2 × 1500 = 3000 lm. Total input = 2 × 20 + 10 = 50 W. Efficacy = 3000/50 = 60 lm/W. 30 uses one lamp's flux; 75 omits ballast power; 150 divides by one lamp's power only.

   Reference: Power Engineering, Fourth Class, Part B, Unit B-8 — Ch.1, Use of Efficient Light Sources

8. 8An air-handler calculation uses a saturation moisture capacity of 10 g for a fixed quantity of air at the inlet and 20 g after heating. Inlet relative humidity is 50%, and no moisture is added or removed. Using the stated mass-ratio basis, what is the outlet relative humidity?

   1. A.25%Correct answer: A
   2. B.50%
   3. C.75%
   4. D.100%

   Explanation: The textbook states, "Relative humidity is the ratio of the mass of moisture contained in a given amount of air to the maximum amount of moisture this air can contain at that temperature. It is usually expressed as a percentage." Initial actual moisture = 0.50 × 10 g = 5 g. With the same 5 g after heating, RH = 5/20 × 100% = 25%. The 50% choice leaves RH unchanged; 75% uses the unfilled fraction (20−5)/20; 100% reverses the capacity ratio, 50% × 20/10.

   Reference: Power Engineering, Fourth Class, Part B, Unit B-10 — Chapter 1, Relative Humidity (RH)

9. 9Steam reaches a cold bellows-type thermostatic radiator trap. As its bellows filling vaporizes, how does the trap respond?

   1. A.The bellows contracts and opens the discharge valve.
   2. B.The bellows expands and closes the discharge valve.Correct answer: B
   3. C.The bellows expands and opens the discharge valve.
   4. D.The bellows contracts and closes the discharge valve.

   Explanation: The textbook states, "The steam causes the fluid in the bellows to evaporate, and the bellows expands from the increased pressure. The valve then seats itself to prevent the loss of steam." The expanding bellows closes the valve against live steam. Contraction and opening occur when the trap cools.

   Reference: Power Engineering, Fourth Class, Part B, Unit B-11 — Chapter 1, Radiator Traps

10. 10An operator works at a mill where spent alkaline cooking liquor is concentrated and burned to recover pulping chemicals and generate steam. Which plant configuration uses this black-liquor recovery cycle?

    1. A.Kraft pulp millCorrect answer: A
    2. B.Mechanical pulp mill
    3. C.Recycled-paper mill
    4. D.Sulfite pulp mill

    Explanation: The textbook states, "The economic viability of a kraft pulp mill is highly dependent on the ability to recover the spent pulping chemicals for re-use." Kraft pulping uses the described alkaline chemical recovery cycle. Mechanical and recycled-fibre processing do not use that cooking-liquor cycle; sulfite pulping uses a different chemical process.

    Reference: Power Engineering, Fourth Class, Part B, Unit B-12 — Chapter 2, Chemical Recovery