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Level Transmitter MCQ Test

Test yourself with 20 multiple choice questions. Check your answers to get a score and an explanation for every question.

20 questionsInstant scoreExplanationsInterview practice

Level Transmitter MCQ Test: 20 Questions

Choose one answer for each question, then press Check answers. Explanations appear after checking.

1. Hydrostatic level h equals:

Answer: p ÷ (ρ g). h = p ÷ (ρ × g). Learn more: Hydrostatic Level Measurement

2. If liquid density falls, a DP level transmitter reads:

Answer: Low. Less pressure per metre is read as less level. Learn more: DP Level Measurement

3. A dry leg is used when vapour:

Answer: Does not condense. Condensing vapour would slowly fill the leg; then a wet leg is used. Learn more: Dry Leg

4. With a wet leg the DP at full level is often near:

Answer: Zero. Process head on HP equals leg head on LP. Learn more: Wet Leg

5. Radar level is least affected by:

Answer: Vapour, temperature and pressure. Microwaves travel almost unaffected through gases. Learn more: Radar Level Transmitter
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6. Ultrasonic level transmitters compensate for:

Answer: Air temperature. Speed of sound changes with temperature. Learn more: Ultrasonic Level Transmitter

7. Blocking distance is:

Answer: The dead zone just below the sensor. Echoes in this zone are lost while the sensor rings down. Learn more: Blocking Distance

8. Guided wave radar can measure interface when the upper liquid has:

Answer: Lower dielectric constant than the lower liquid. Part of the pulse passes the upper layer and reflects from the interface. Learn more: Guided Wave Radar

9. A displacer measures level from:

Answer: Buoyancy force. Apparent weight falls as more of it is submerged. Learn more: Displacer Level Transmitter

10. Vibrating fork switches detect liquid by:

Answer: Drop in resonant frequency. Liquid around the tines lowers the frequency. Learn more: Vibrating Fork Level Switch
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11. Radar reflection is strongest from:

Answer: Water. Water has εr about 80. Learn more: Dielectric Constant

12. False echo suppression should be mapped:

Answer: With low level, up to just above the surface. Mapping below the surface can hide the real echo. Learn more: False Echo Suppression

13. Ullage is:

Answer: Empty space from reference down to the surface. Level = reference height − ullage. Learn more: Ullage

14. Volume of one 2:1 ellipsoidal head of diameter D is:

Answer: π D³ ÷ 24. Half of an ellipsoid with axes D/2, D/2, D/4. Learn more: Dished Head

15. Load cell tank weighing is independent of:

Answer: Density and foam. It measures mass directly, but mechanical forces add errors. Learn more: Load Cell Tank Weighing
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16. A bubbler measures level from:

Answer: Purge gas back pressure at the dip tube end. Back pressure equals the hydrostatic head. Learn more: Bubbler Level Measurement

17. Overfill protection normally needs:

Answer: An independent high high level sensor. Independence avoids common cause failure with the control loop. Learn more: Overfill Protection

18. A stilling well helps radar by:

Answer: Calming the surface and guiding the signal. It gives a calm, reflective surface. Learn more: Stilling Well

19. Holdup time between two levels equals:

Answer: Volume between levels ÷ net flow. t = V ÷ Q. Learn more: Vessel Holdup Time

20. Radiometric level gauges use:

Answer: A gamma source and detector outside the vessel. Nothing is in contact with the process. Learn more: Radiometric Level Measurement
0 of 20 answered
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About this Quiz

20 multiple choice questions on level transmitter mcq test, the kind asked in instrumentation interviews, technician exams and plant training. Each answer comes with a short explanation, so the quiz works as a revision sheet too.

Show answer key
  1. p ÷ (ρ g): h = p ÷ (ρ × g). Learn more: Hydrostatic Level Measurement
  2. Low: Less pressure per metre is read as less level. Learn more: DP Level Measurement
  3. Does not condense: Condensing vapour would slowly fill the leg; then a wet leg is used. Learn more: Dry Leg
  4. Zero: Process head on HP equals leg head on LP. Learn more: Wet Leg
  5. Vapour, temperature and pressure: Microwaves travel almost unaffected through gases. Learn more: Radar Level Transmitter
  6. Air temperature: Speed of sound changes with temperature. Learn more: Ultrasonic Level Transmitter
  7. The dead zone just below the sensor: Echoes in this zone are lost while the sensor rings down. Learn more: Blocking Distance
  8. Lower dielectric constant than the lower liquid: Part of the pulse passes the upper layer and reflects from the interface. Learn more: Guided Wave Radar
  9. Buoyancy force: Apparent weight falls as more of it is submerged. Learn more: Displacer Level Transmitter
  10. Drop in resonant frequency: Liquid around the tines lowers the frequency. Learn more: Vibrating Fork Level Switch
  11. Water: Water has εr about 80. Learn more: Dielectric Constant
  12. With low level, up to just above the surface: Mapping below the surface can hide the real echo. Learn more: False Echo Suppression
  13. Empty space from reference down to the surface: Level = reference height − ullage. Learn more: Ullage
  14. π D³ ÷ 24: Half of an ellipsoid with axes D/2, D/2, D/4. Learn more: Dished Head
  15. Density and foam: It measures mass directly, but mechanical forces add errors. Learn more: Load Cell Tank Weighing
  16. Purge gas back pressure at the dip tube end: Back pressure equals the hydrostatic head. Learn more: Bubbler Level Measurement
  17. An independent high high level sensor: Independence avoids common cause failure with the control loop. Learn more: Overfill Protection
  18. Calming the surface and guiding the signal: It gives a calm, reflective surface. Learn more: Stilling Well
  19. Volume between levels ÷ net flow: t = V ÷ Q. Learn more: Vessel Holdup Time
  20. A gamma source and detector outside the vessel: Nothing is in contact with the process. Learn more: Radiometric Level Measurement
Tip: take the quiz before an interview, note the questions you missed and read the linked article for those topics.
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Frequently Asked Questions

Is this quiz free?

Yes. No sign up is needed and you can retake it as often as you like.

Are the answers explained?

Yes. After you check your answers, each question shows the correct answer and a short explanation.

Where can I find more questions?

See the Interview Q&A section of instrumentationblog.in and the linked article below.

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