Types of manometers MCQs With Answer

Introduction: Understanding Types of manometers MCQs With Answer is essential for B. Pharm students studying pressure measurement and instrumentation in pharmaceutical processes. This concise guide covers manometer types—U-tube, differential, inclined, well-type and digital—along with working principles, fluid selection, calibration, error sources and safety (mercury hazards). Emphasis on hydrostatic relationships (P = ρgh), unit conversions (mmHg, cmH2O, Pa) and practical applications in HVAC, cleanrooms, autoclaves and filling lines makes the topic directly relevant to pharmaceutical operations and quality control. Use these targeted practice questions to master concepts, calculations and real-world uses. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the basic hydrostatic relation used in most liquid manometer calculations?

• P = ρgh
• P = ρg/h
• P = ρ + gh
• P = g/ρh

Correct Answer: P = ρgh

Q2. Which type of manometer is best suited for measuring small pressure differences with higher sensitivity?

• Inclined manometer
• Well-type manometer
• U-tube manometer
• Bourdon gauge

Correct Answer: Inclined manometer

Q3. A U-tube manometer contains mercury. If one side is 5 cm higher than the other, what principle explains the pressure difference?

• Archimedes’ principle
• Hydrostatic equilibrium
• Bernoulli’s theorem
• Boyle’s law

Correct Answer: Hydrostatic equilibrium

Q4. Which manometer type minimizes fluid consumption for large displacements by using a reservoir?

• Inclined manometer
• Well-type manometer
• U-tube manometer
• Digital pressure transducer

Correct Answer: Well-type manometer

Q5. For measuring absolute pressure rather than gauge pressure, which reference must be used?

• Atmospheric pressure
• Vacuum (zero pressure)
• Gauge zero
• Manometer liquid density

Correct Answer: Vacuum (zero pressure)

Q6. Which manometer fluid is commonly avoided today due to toxicity concerns despite good density?

• Water
• Mineral oil
• Mercury
• Glycerin

Correct Answer: Mercury

Q7. In a differential manometer connecting two vessels, what does the height difference represent?

• The average of the two pressures
• The sum of the two pressures
• The pressure difference between the two vessels
• The absolute pressure of one vessel

Correct Answer: The pressure difference between the two vessels

Q8. How is pressure difference in an inclined manometer read to improve resolution?

• Measure horizontal displacement
• Measure vertical displacement only
• Measure along the incline length
• Use optical magnification

Correct Answer: Measure along the incline length

Q9. Which unit is NOT typically used in manometer readings?

• mmHg
• cmH2O
• Pascal (Pa)
• Liters per minute (L/min)

Correct Answer: Liters per minute (L/min)

Q10. When converting pressure from cmH2O to mmHg, what property is essential?

• Surface tension of liquid
• Density of the manometer fluid
• Viscosity of the manometer fluid
• Temperature of the gas

Correct Answer: Density of the manometer fluid

Q11. What error source becomes significant in long U-tube manometer columns?

• Capillary action and temperature expansion
• Magnetic interference
• Electrical noise
• Radiation pressure

Correct Answer: Capillary action and temperature expansion

Q12. For low-pressure pharmaceutical cleanroom monitoring, which manometer is commonly used?

• Bourdon gauge
• Inclined manometer or U-tube
• McLeod gauge
• Thermocouple

Correct Answer: Inclined manometer or U-tube

Q13. Which statement about manometer fluid selection is TRUE?

• High-density fluids reduce column height for a given pressure.
• Low-density fluids always give more accurate readings.
• Viscosity is irrelevant for static readings.
• Surface tension increases measurement accuracy.

Correct Answer: High-density fluids reduce column height for a given pressure.

Q14. Which manometer is suitable for measuring very high vacuum levels in laboratory settings?

• U-tube mercury manometer
• Inclined manometer
• McLeod gauge
• Well-type manometer

Correct Answer: McLeod gauge

Q15. In a gas line, a manometer shows a steady offset despite zero differential; likely cause?

• Proper calibration
• Air trapped in the manometer fluid or residue
• Correct fluid density
• Normal operation

Correct Answer: Air trapped in the manometer fluid or residue

Q16. Which is an advantage of digital manometers over liquid manometers in pharma labs?

• Requires mercury handling
• Higher sensitivity to vibration
• Electronic data logging and portability
• No calibration needed ever

Correct Answer: Electronic data logging and portability

Q17. What effect does temperature increase have on manometer fluid density and reading if not corrected?

• Density increases, reading increases
• Density decreases, reading underestimates pressure
• No effect on density
• Reading becomes more accurate

Correct Answer: Density decreases, reading underestimates pressure

Q18. Which manometer configuration includes a long calibrated tube at an angle to improve sensitivity?

• U-tube manometer
• Inclined manometer
• Well-type manometer
• Bourdon tube

Correct Answer: Inclined manometer

Q19. For measuring differential pressure across a HEPA filter, which property matters most?

• Color of manometer liquid
• Pressure drop sensitivity and stability
• Electrical conductivity
• Magnetic susceptibility

Correct Answer: Pressure drop sensitivity and stability

Q20. Which manometer is often used when one side is open to atmosphere and the other to process gas?

• Differential manometer with both sealed ends
• Single-column gauge or simple U-tube referenced to atmosphere
• McLeod gauge
• Inclined manometer used as absolute gauge

Correct Answer: Single-column gauge or simple U-tube referenced to atmosphere

Q21. In pharmaceutical autoclave validation, manometers help monitor what critical parameter?

• pH of solutions
• Sterilization pressure and pressure profiles
• Tablet dissolution rate
• Optical density

Correct Answer: Sterilization pressure and pressure profiles

Q22. If a manometer uses two immiscible fluids, what additional factor must be considered?

• Interface tension and density difference
• Color matching of fluids
• Electrical conductivity match
• Magnetic alignment

Correct Answer: Interface tension and density difference

Q23. Which term describes the pressure read relative to atmospheric pressure?

• Absolute pressure
• Gauge pressure
• Vapor pressure
• Osmotic pressure

Correct Answer: Gauge pressure

Q24. What safety practice is crucial when using mercury manometers in a lab?

• Store them in direct sunlight
• Use PPE and proper spill containment
• Heat mercury to reduce viscosity
• Dispose into sink to dilute

Correct Answer: Use PPE and proper spill containment

Q25. How does capillary rise in narrow tubes affect manometer readings?

• It has no effect
• It causes systematic error, especially with low-density fluids
• It improves accuracy always
• It cancels out temperature effects

Correct Answer: It causes systematic error, especially with low-density fluids

Q26. What is the primary limitation of a simple U-tube manometer?

• Cannot measure any pressure
• Requires large vertical space for high pressures
• Too specific for vacuum only
• Not affected by fluid density

Correct Answer: Requires large vertical space for high pressures

Q27. When using a manometer to measure gas pressure, why is it important to avoid entrained air bubbles in the fluid?

• Bubbles improve responsiveness
• Bubbles cause erroneous readings and damping
• Bubbles stabilize the meniscus
• Bubbles increase fluid density

Correct Answer: Bubbles cause erroneous readings and damping

Q28. Which pressure-measuring instrument provides a direct electrical output suitable for data logging?

• U-tube manometer
• Digital/electronic manometer (transducer)
• Inclined glass manometer
• Well-type mercury manometer

Correct Answer: Digital/electronic manometer (transducer)

Q29. In manometer calculations, what does ρ represent?

• Pressure head
• Density of the manometer fluid
• Viscosity of the gas
• Radius of tube

Correct Answer: Density of the manometer fluid

Q30. For an inclined manometer with angle θ, how does the slope affect the relationship between vertical height h and length along the tube s?

• h = s × cos(θ)
• h = s × tan(θ)
• h = s / cos(θ)
• h = s × sin(θ)

Correct Answer: h = s × sin(θ)

Q31. Which manometer is more appropriate when monitoring differential pressure across production filters with very small expected drops?

• Standard vertical U-tube with mercury
• Inclined manometer for increased sensitivity
• McLeod gauge
• Bourdon tube gauge

Correct Answer: Inclined manometer for increased sensitivity

Q32. What is the effect of using a lighter fluid instead of mercury in a manometer for the same pressure?

• Column height decreases
• Column height increases
• No change in column height
• Fluid becomes magnetic

Correct Answer: Column height increases

Q33. Which calibration check is appropriate for a manometer used in pharmaceutical QC?

• Ignore calibration if new
• Compare readings against a traceable standard at multiple points
• Calibrate only once after installation
• Use arbitrary reference pressures

Correct Answer: Compare readings against a traceable standard at multiple points

Q34. In two-fluid differential manometers, why is the interface position essential?

• It determines the color contrast
• It indicates the pressure difference using density difference
• Interface position is irrelevant
• It only affects viscosity

Correct Answer: It indicates the pressure difference using density difference

Q35. Which measurement condition can invalidate simple hydrostatic manometer assumptions?

• Static, no flow
• Turbulent flow with rapid acceleration
• Isothermal conditions
• Negligible gravity

Correct Answer: Turbulent flow with rapid acceleration

Q36. What is the correct way to read a meniscus in a transparent manometer tube for aqueous fluids?

• Read from top of meniscus
• Read from bottom of meniscus
• Average top and bottom
• Ignore meniscus and estimate

Correct Answer: Read from bottom of meniscus

Q37. For measuring high positive pressures in production, which instrument is more robust than a liquid manometer?

• Inclined glass manometer
• Bourdon tube gauge
• U-tube with water
• Open well manometer

Correct Answer: Bourdon tube gauge

Q38. Which phrase describes a manometer reading when one side is evacuated (vacuum) and the other at process pressure?

• Gauge pressure
• Differential to atmosphere
• Absolute pressure measurement relative to vacuum
• Osmotic pressure

Correct Answer: Absolute pressure measurement relative to vacuum

Q39. When using a manometer with colored glycerin, what is an advantage?

• Higher toxicity
• Reduced vapor pressure and better visibility
• Increases capillary rise
• Incompatible with all gases

Correct Answer: Reduced vapor pressure and better visibility

Q40. In pharmaceutical HVAC, small positive differential pressure between rooms indicates what?

• Cross-contamination risk into cleanroom
• Airflow from cleanroom to adjacent area maintaining cleanliness
• System failure always
• No airflow control required

Correct Answer: Airflow from cleanroom to adjacent area maintaining cleanliness

Q41. What is a common unit for very small pressure differences measured in cleanrooms?

• Bar
• inH2O (inches of water)
• kg
• Liter

Correct Answer: inH2O (inches of water)

Q42. Which factor should be recorded alongside manometer readings for traceability in validation?

• Operator’s favorite color
• Ambient temperature and calibration certificate
• Only the reading value is needed
• Time of day only

Correct Answer: Ambient temperature and calibration certificate

Q43. What does a negative reading on a gauge manometer relative to atmospheric indicate?

• Positive gauge pressure
• Vacuum or pressure below atmospheric
• Instrument malfunction only
• Higher than atmospheric pressure

Correct Answer: Vacuum or pressure below atmospheric

Q44. Which maintenance action reduces contamination risk in manometers used in pharmaceutical settings?

• Never clean them
• Regular cleaning, fluid replacement and proper sealing
• Replace fluid with tap water only
• Leave open to atmosphere for drying

Correct Answer: Regular cleaning, fluid replacement and proper sealing

Q45. What is the advantage of a differential U-tube manometer with unequal fluid columns?

• No calibration required
• Allows measurement when one side pressure is near atmospheric using reference fluid
• Eliminates need for density
• Makes it immune to temperature changes

Correct Answer: Allows measurement when one side pressure is near atmospheric using reference fluid

Q46. How does surface tension of the manometer fluid affect the reading in narrow bore tubes?

• Causes meniscus curvature leading to reading errors
• Eliminates hydrostatic pressure
• Turns fluid into gas
• Has no effect irrespective of tube size

Correct Answer: Causes meniscus curvature leading to reading errors

Q47. For calibration, a manometer is compared to a dead-weight tester. What does the dead-weight tester provide?

• Known electrical signal
• Traceable, accurate reference pressure from applied weights
• Arbitrary pressure values
• Temperature reference only

Correct Answer: Traceable, accurate reference pressure from applied weights

Q48. When designing a manometer system for corrosive gases, what is critical?

• Use of reactive metals in tubing
• Selection of compatible wetted materials and fluids
• Use of mercury regardless of corrosion
• Ignore material compatibility

Correct Answer: Selection of compatible wetted materials and fluids

Q49. In practical calculations, why might you correct manometer readings for gravity variations?

• Gravity is constant everywhere
• Elevation changes can slightly affect ρg term for high accuracy work
• Gravity changes color of fluid
• Gravity affects only temperature

Correct Answer: Elevation changes can slightly affect ρg term for high accuracy work

Q50. Which best practice helps ensure reliable manometer data during pharmaceutical batch runs?

• Record single reading at end of run
• Periodic monitoring, logging, sensor checks and calibration traceability
• Rely solely on visual inspection
• Use uncalibrated instruments for convenience

Correct Answer: Periodic monitoring, logging, sensor checks and calibration traceability

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com