Pitot tube MCQs With Answer are essential study tools for B. Pharm students learning fluid dynamics and instrumentation relevant to pharmaceutical processes. This concise, Student-friendly post covers Pitot tube principles, Pitot-static configurations, velocity and differential pressure relationships, calibration, common errors, and applications in aerosol inhaler testing, cleanroom airflow validation, and HVAC systems in pharma facilities. Understanding equations like v = sqrt(2Δp/ρ), stagnation versus static pressure, and factors affecting accuracy (angle, blockage, compressibility) helps pharmacy graduates interpret flow measurements confidently. These MCQs with answers reinforce core concepts, practical troubleshooting, and calculation skills needed for laboratory and industrial settings. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What does a Pitot tube primarily measure?
- Static pressure only
- Velocity pressure (dynamic pressure)
- Temperature of the fluid
- Viscosity of the fluid
Correct Answer: Velocity pressure (dynamic pressure)
Q2. In a Pitot-static arrangement, stagnation pressure equals:
- Static pressure minus dynamic pressure
- Static pressure only
- Static pressure plus dynamic pressure
- Dynamic pressure only
Correct Answer: Static pressure plus dynamic pressure
Q3. The formula v = sqrt(2Δp/ρ) relates velocity v to:
- Static pressure difference and viscosity
- Dynamic pressure difference and density
- Temperature difference and density
- Viscosity and flow rate
Correct Answer: Dynamic pressure difference and density
Q4. Which device is commonly used to read the differential pressure from a Pitot tube?
- Thermocouple
- Manometer or differential pressure transducer
- Refractometer
- pH meter
Correct Answer: Manometer or differential pressure transducer
Q5. For incompressible flow assumptions with Pitot tubes, which fluid property is most important?
- Density
- Surface tension
- Color
- Dielectric constant
Correct Answer: Density
Q6. Which error occurs if a Pitot tube is not aligned with the flow direction?
- Thermal drift
- Angle-of-attack error leading to underestimated velocity
- Overpressure calibration
- Viscous heating
Correct Answer: Angle-of-attack error leading to underestimated velocity
Q7. A Prandtl tube is another name for:
- A Pitot-static tube
- A temperature sensor
- An ultrasonic flowmeter
- A rotameter
Correct Answer: A Pitot-static tube
Q8. When measuring compressible gas flow at high Mach numbers, you must apply:
- No correction
- Compressibility correction factors
- Colorimetric adjustment
- pH correction
Correct Answer: Compressibility correction factors
Q9. In aerosol inhaler testing, Pitot tubes help measure:
- Particle chemical composition
- Airflow velocity and device outlet pressure
- Tablet dissolution rate
- Active pharmaceutical ingredient purity
Correct Answer: Airflow velocity and device outlet pressure
Q10. The dynamic pressure measured by a Pitot tube is also called:
- Hydrostatic head
- Velocity head
- Thermal head
- Acoustic pressure
Correct Answer: Velocity head
Q11. What happens to Pitot readings if the probe opening is partially blocked?
- Readings remain accurate
- Readings become erratic or lower than true values
- Readings increase proportionally
- Temperature measurement improves
Correct Answer: Readings become erratic or lower than true values
Q12. The Pitot tube measures total pressure when its opening faces:
- Perpendicular to the flow
- Away from the flow
- Directly into the flow (stagnation point)
- Alongside the boundary layer
Correct Answer: Directly into the flow (stagnation point)
Q13. Which factor must be known to convert measured Δp to velocity using v = sqrt(2Δp/ρ)?
- Fluid viscosity only
- Fluid density
- Tube color
- Ambient humidity only
Correct Answer: Fluid density
Q14. In pharmaceutical cleanrooms, Pitot tubes are used to verify:
- Microbial counts
- Air velocity profiles and laminar flow
- Drug potency
- pH of cleaning solutions
Correct Answer: Air velocity profiles and laminar flow
Q15. Which component of Bernoulli’s equation is directly measured by a Pitot tube?
- Elevation head
- Stagnation pressure (total pressure)
- Thermal energy
- Viscous dissipation
Correct Answer: Stagnation pressure (total pressure)
Q16. For low Reynolds number flows, Pitot tube measurements may be affected by:
- Magnetic interference
- Viscous effects and distorted velocity profile
- Radioactive decay
- Optical refraction
Correct Answer: Viscous effects and distorted velocity profile
Q17. Which maintenance practice improves Pitot tube accuracy?
- Painting the probe
- Regular cleaning and checking for blockages
- Submerging it in solvent permanently
- Heating the probe continuously
Correct Answer: Regular cleaning and checking for blockages
Q18. A multiport Pitot tube is used to:
- Measure temperature gradients
- Average velocity across a duct cross-section
- Measure color changes in aerosols
- Determine chemical composition
Correct Answer: Average velocity across a duct cross-section
Q19. If Δp = 200 Pa and air density ρ = 1.2 kg/m3, the approximate velocity is:
- 18 m/s
- 0.17 m/s
- 200 m/s
- 9 m/s
Correct Answer: 18 m/s
Q20. Stagnation pressure equals static pressure when:
- Flow velocity is zero (stagnant fluid)
- Flow is supersonic
- Temperature is very high
- Fluid is compressible
Correct Answer: Flow velocity is zero (stagnant fluid)
Q21. Which reading device provides the highest sensitivity for small Δp from a Pitot tube?
- U-tube manometer
- High-resolution differential pressure transducer
- Thermistor
- Analog clock
Correct Answer: High-resolution differential pressure transducer
Q22. The presence of a thick boundary layer near duct walls affects Pitot tube readings by:
- Enhancing signal strength
- Underestimating local velocity if probe is within boundary layer
- Causing chemical reactions
- Increasing temperature readings
Correct Answer: Underestimating local velocity if probe is within boundary layer
Q23. Which Pitot tube design helps reduce orientation errors in turbulent flows?
- Simple open tube
- Multi-hole yaw-correcting Pitot tube
- Glass capillary
- Weighted rod
Correct Answer: Multi-hole yaw-correcting Pitot tube
Q24. When using a Pitot tube in liquid instead of gas, what changes in the velocity calculation?
- Use liquid density for ρ in v = sqrt(2Δp/ρ)
- Use gas density regardless
- Equation becomes v = Δp/ρ
- Velocity cannot be measured in liquids
Correct Answer: Use liquid density for ρ in v = sqrt(2Δp/ρ)
Q25. Which principle underlies Pitot tube operation?
- Hooke’s law
- Bernoulli’s principle (energy conservation in fluid flow)
- Nernst equation
- Faraday’s law
Correct Answer: Bernoulli’s principle (energy conservation in fluid flow)
Q26. The impact of temperature on Pitot measurements is mainly through:
- Change in fluid viscosity only
- Change in fluid density and possibly sensor calibration
- Change in gravitational constant
- Color change of the probe
Correct Answer: Change in fluid density and possibly sensor calibration
Q27. Which is a common application of Pitot tubes in pharmaceutical R&D?
- Tablet coating thickness measurement
- Inhaler spray velocity and airflow characterization
- Determining API molecular weight
- Measuring buffer pH
Correct Answer: Inhaler spray velocity and airflow characterization
Q28. If measured Δp is zero in a flowing duct, possible reasons include:
- Probe fully aligned and flow normal
- Probe is in free-stream and tube is blocked or static and stagnation equals static
- Fluid has infinite density
- Sensor measures temperature not pressure
Correct Answer: Probe is in free-stream and tube is blocked or static and stagnation equals static
Q29. When validating HVAC airflow in a cleanroom, which Pitot tube method is standard?
- Single-point measurement at random location
- Grid sampling across duct cross-section using multiport probe
- Only visual inspection
- Using pH strips
Correct Answer: Grid sampling across duct cross-section using multiport probe
Q30. The dynamic pressure in a flow is numerically equal to:
- ρv/2
- ρv^2/2
- ρgH
- Pstatic – Ptotal
Correct Answer: ρv^2/2
Q31. In a Pitot-static tube, the static port should be located:
- Facing directly into the flow
- Perpendicular to the flow to sample undisturbed static pressure
- In the boundary layer only
- At the duct center only
Correct Answer: Perpendicular to the flow to sample undisturbed static pressure
Q32. Why are correction factors sometimes applied to Pitot readings?
- To account for color of probe
- To correct for non-uniform velocity profiles and probe geometry
- To measure chemical concentration
- To adjust pH readings
Correct Answer: To correct for non-uniform velocity profiles and probe geometry
Q33. Which flow regime is more likely to produce stable Pitot readings across repeated samples?
- Turbulent chaotic flow
- Laminar, fully developed flow
- Transitional flow always
- Oscillatory flow only
Correct Answer: Laminar, fully developed flow
Q34. For compressible flows with Pitot tubes, total pressure must be corrected for:
- Mach number and temperature effects
- pH and salinity
- Electrical conductivity
- Optical density
Correct Answer: Mach number and temperature effects
Q35. Which of the following is NOT a typical source of error in Pitot measurements?
- Probe misalignment
- Blockage or dirt in the port
- Fluid color change
- Incorrect density used in calculation
Correct Answer: Fluid color change
Q36. In practice, taking Pitot readings at multiple radial positions in a duct helps to:
- Determine chemical composition
- Compute average flow and account for velocity profile
- Measure luminescence
- Check sound levels
Correct Answer: Compute average flow and account for velocity profile
Q37. Which equation is often combined with Pitot measurements for volumetric flow rate in a circular duct?
- Q = A × v (area times mean velocity)
- Q = m × c
- Q = pH × volume
- Q = T × R
Correct Answer: Q = A × v (area times mean velocity)
Q38. Which instrument would you use to verify Pitot tube calibration?
- Calibrated differential pressure standard or wind tunnel with known velocity
- pH meter
- Mass spectrometer
- Optical microscope
Correct Answer: Calibrated differential pressure standard or wind tunnel with known velocity
Q39. When measuring flow near a fan or pump outlet, Pitot readings may be affected by:
- Uniform laminar profile
- Swirl and non-uniform velocity distribution
- Complete absence of flow
- Stable chemical composition
Correct Answer: Swirl and non-uniform velocity distribution
Q40. Pitot tubes in respiratory device testing must consider:
- Only static pressure
- Low flow rates, humidity, transient flows, and probe intrusion effects
- Color and aroma of the aerosol
- Only chemical assay results
Correct Answer: Low flow rates, humidity, transient flows, and probe intrusion effects
Q41. The stagnation temperature measured at a Pitot tube impact point equals:
- Ambient temperature always
- Static temperature plus kinetic energy term divided by specific heat (for adiabatic flow)
- Only static temperature multiplied by density
- Temperature unrelated to flow
Correct Answer: Static temperature plus kinetic energy term divided by specific heat (for adiabatic flow)
Q42. Which cleaning protocol is appropriate for metallic Pitot probes used in cleanrooms?
- Autoclave every day regardless of material
- Follow manufacturer guidance using appropriate solvents and lint-free swabs to avoid contamination
- Dip in strong acid without rinsing
- Never clean to preserve calibration
Correct Answer: Follow manufacturer guidance using appropriate solvents and lint-free swabs to avoid contamination
Q43. The term “velocity head” is numerically equal to:
- v
- v^2/(2g)
- ρv
- g/v^2
Correct Answer: v^2/(2g)
Q44. Why might a Pitot tube under-read velocity in a duct with strong swirl?
- Because the probe measures chemical composition
- The axial component of velocity is reduced relative to total flow, so the probe senses a lower axial dynamic pressure
- Swirl increases fluid density artificially
- Swirl neutralizes static pressure
Correct Answer: The axial component of velocity is reduced relative to total flow, so the probe senses a lower axial dynamic pressure
Q45. When converting Pitot Δp to velocity for helium vs air, what must you change?
- Nothing, helium and air are same
- Use the appropriate fluid density for helium in the equation
- Invert the equation
- Use viscosity of air regardless
Correct Answer: Use the appropriate fluid density for helium in the equation
Q46. Which design reduces clogging risk in aerosol-rich environments?
- Very small-diameter single port
- Use of protective screens and larger-diameter ports or heated probes
- Unprotected open ports only
- Sealed probes without ports
Correct Answer: Use of protective screens and larger-diameter ports or heated probes
Q47. The Pitot coefficient or calibration factor accounts for:
- Electrical wiring errors
- Probe geometry and non-ideal flow effects to correct measured Δp to true dynamic pressure
- Ambient light levels
- Color of the probe
Correct Answer: Probe geometry and non-ideal flow effects to correct measured Δp to true dynamic pressure
Q48. In wind tunnel testing for inhaler sprays, Pitot tubes help determine:
- API chemical structure
- Freestream velocity and conditions for particle trajectory studies
- Tablet hardness
- pH of aerosols
Correct Answer: Freestream velocity and conditions for particle trajectory studies
Q49. A Pitot tube measures lower dynamic pressure near walls due to:
- Higher temperature near walls
- Reduced velocity in the boundary layer
- Increase in chemical concentration
- Magnetic forces from walls
Correct Answer: Reduced velocity in the boundary layer
Q50. Best practice when reporting Pitot-based airflow results in a validation report is to include:
- Only numerical velocities without context
- Measurement method, probe type, calibration data, positions sampled, Δp values, and calculation assumptions
- Only the brand of the probe
- Only a photograph of the setup
Correct Answer: Measurement method, probe type, calibration data, positions sampled, Δp values, and calculation assumptions
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