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10 free 4B practice questions (printable)

Ten original exam-style 4th Class Part B (4B) questions from our free public sample, written to the public syllabus. Work them on paper, then check the answer key at the end. They are not questions from a real exam, and a score here does not predict your exam result.

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1. Which of the following is NOT a cause of antifriction bearing failure described in this unit?

  • A. Misalignment of the shaft causing uneven loading
  • B. Storing a cleaned bearing wrapped in greaseproof paper
  • C. Improper fitting that brinells the races during installation
  • D. Poor quality, incorrect, or old lubricant

Question ID KE-B01-C02-Q005 · Unit B-1: Lubrication and Bearings · Report an error

2. Which task is performed as a routine MONTHLY check on an air compression system?

  • A. Checking the lubricating oil and the coolant levels on every operating day
  • B. Draining and thoroughly cleaning each lubrication and coolant system on the unit
  • C. Analyzing oil samples taken from the lubricating oil and seal oil reservoirs
  • D. Listening carefully for any unusual noises from the machine during each shift

Question ID KE-B02-C04-Q031 · Unit B-2: Pumps and Compressors · Report an error

3. According to ASME PTC-25, which type of pressure relief valve is characterized by rapid opening and is normally used to relieve compressible fluids such as steam?

  • A. Safety relief valve
  • B. Relief valve
  • C. Safety valve
  • D. Temperature and pressure (T&P) relief valve

Question ID KE-B03-C01-Q001 · Unit B-3: Boiler Safety Devices · Report an error

4. What is the concern if a high-low boiler is started from cold with the HI-LO-AUTO switch set to AUTO?

  • A. The boiler may jump to high-fire, causing uneven expansion and excessive stress
  • B. The burner may fail to light because the pilot is starved of air during the pilot trial for ignition
  • C. The modulating motor may stall between the high and low fire positions
  • D. The low water cut-off may trip before the burner establishes a flame

Question ID KE-B03-C05-Q009 · Unit B-3: Boiler Safety Devices · Report an error

5. During an accumulation test, a power boiler with an MAWP of 2415 kPa and a safety valve set at 2070 kPa stabilizes at 2200 kPa while the valve is fully discharging. Is the safety valve capacity adequate?

  • A. Yes; 2200 kPa is below 6% above the MAWP (about 2560 kPa)
  • B. No; any pressure above the 2070 kPa set point means inadequate capacity
  • C. Yes; 2200 kPa is still well below the MAWP of 2415 kPa
  • D. No; 2200 kPa exceeds 6% above the set pressure (about 2194 kPa)

Question ID KE-B04-C06-Q017 · Unit B-4: Boiler Plant Operation and Management · Report an error

6. When a new blade is installed in a hand hacksaw, how should the teeth be oriented and what should be done to the blade before the saw is stored?

  • A. Teeth point toward the handle, and the blade tension is released before storage
  • B. Teeth point away from the handle, and the blade tension is released before storage
  • C. Teeth point toward the handle, and full tension is kept on the blade during storage
  • D. Teeth point away from the handle, and full tension is kept on the blade during storage

Question ID KE-B05-C01-Q001 · Unit B-5: Energy Plant Maintenance · Report an error

7. Which of the following would an inspector examine during the internal inspection of a boiler?

  • A. The accuracy of the boiler's pressure gauge
  • B. The set point and lift capacity of the safety valve
  • C. The flue gas temperature leaving the unit
  • D. The waterside metal for corrosion, pitting, and cracks

Question ID KE-B05-C04-Q023 · Unit B-5: Energy Plant Maintenance · Report an error

8. Which statement correctly describes how four-stroke and two-stroke spark ignition engines are lubricated?

  • A. Both engines circulate oil drawn from a pressurized crankcase sump
  • B. A four-stroke uses oil mixed with the fuel, while a two-stroke uses pressurized crankcase oil
  • C. Both engines are lubricated only by oil mixed with the fuel
  • D. A four-stroke uses crankcase oil, while a two-stroke uses oil mixed with the fuel as a fog

Question ID KE-B07-C05-Q014 · Unit B-7: Types of Prime Movers and Heat Engines · Report an error

9. Within a vapour compression refrigeration system, which component performs a role most like that of a boiler feedwater regulating valve?

  • A. The compressor on the suction side
  • B. The condenser water regulating valve
  • C. The expansion (metering) valve
  • D. The suction line strainer screen

Question ID KE-B09-C01-Q001 · Unit B-9: Basic Concepts of Compression and Absorption Refrigeration · Report an error

10. Effective temperature is an index of comfort. Which combination of conditions does it account for?

  • A. Dry-bulb temperature, relative humidity, and air movement
  • B. Wet-bulb temperature, barometric pressure, and air movement
  • C. Relative humidity, air cleanliness, and outdoor air temperature
  • D. Dry-bulb temperature, dew point, and the cleanliness of the air

Question ID KE-B10-C01-Q001 · Unit B-10: HVAC Fundamentals for Facility Operators · Report an error

Answer key

  1. 1. B (KE-B01-C02-Q005), Causes of antifriction bearing failure include poor or old lubricant, improper fitting (brinelling), misalignment, false brinelling, and high operating temperatures. Storing a cleaned bearing in rust preventer and greaseproof paper is a correct preservation practice, not a cause of failure.
  2. 2. C (KE-B02-C04-Q031), Monthly checks include assessing the performance of all intercoolers, aftercoolers, and oil coolers; lubricating the linkage, pins, and slide bars of control valves and positioners; and analyzing oil samples from the lubricating and seal oil reservoirs. Listening for unusual noises each shift and checking the oil and coolant levels are daily checks, and draining/cleaning the lube and coolant systems is a major shutdown task.
  3. 3. C (KE-B03-C01-Q001), ASME PTC-25 defines a safety valve as a valve with rapid opening normally used for compressible fluids like steam. A relief valve opens gradually for incompressible fluids, a safety relief valve does either, and a T&P valve adds temperature actuation.
  4. 4. A (KE-B03-C05-Q009), A cold boiler's pressure is below the high-fire cut-in, so with the switch in AUTO it goes immediately to high-fire on start-up. The sudden heat input causes uneven thermal expansion and excessive stress, which is why a cold boiler should be warmed on low-fire first.
  5. 5. D (KE-B04-C06-Q017), ASME I PG-67 allows the pressure to rise no more than 6% above the highest set pressure; 6% above 2070 kPa is about 2194 kPa, and the stabilized 2200 kPa exceeds it, so capacity is inadequate. Comparing only to the MAWP or to MAWP plus 6% is incorrect, and some accumulation above the set point is permitted, so claiming that any pressure above the 2070 kPa set point means inadequate capacity is also wrong.
  6. 6. B (KE-B05-C01-Q001), A new blade is fitted with the teeth pointing away from the handle and tensioned with the wing nut so it cuts straight; the tension must be released when the hacksaw is stored to protect the blade and frame.
  7. 7. D (KE-B05-C04-Q023), The internal inspection examines the waterside and fireside metal for corrosion, pitting, and cracking. Gauge accuracy, flue gas temperature, and safety valve set point are checked during the external inspection conducted while the boiler is in service.
  8. 8. D (KE-B07-C05-Q014), A four-stroke spark-ignition engine keeps oil in the crankcase and delivers it by a pump or by splash from the crank. A two-stroke carries oil with the gasoline as a mist, either mixed into the fuel or injected on newer engines. Swapping those two methods, or treating both engines as lubricated the same way, does not match how they are built.
  9. 9. C (KE-B09-C01-Q001), Just as a feedwater valve meters water into a boiler, the expansion (metering) valve meters liquid refrigerant into the evaporator while dropping its pressure. This makes it the closest functional analogue to a boiler feedwater regulating valve.
  10. 10. A (KE-B10-C01-Q001), Effective temperature is described as a measure of comfort that combines the effects of dry-bulb temperature, relative humidity, and air movement; it is not an actual measurable temperature.

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