Free Fluid Flow Operations MCQs with Answers

• A. Speed of the fan
• B. Damper
• C. Variation in the pitch of the fan blades
• D. All A., B. and C.

Explanation: Fan-produced draught can be adjusted by changing fan speed, throttling with a damper, or changing blade pitch in a variable-pitch fan.

• A. > 2 (gage)
• B. < atmospheric
• C. < 10 (gage)
• D. < 3 (gage)

Explanation: Liquid-column manometers are mainly used for low to moderate pressure differences, commonly below about 3 kgf/cm² gauge.

• A. Gauge
• B. Absolute
• C. Atmospheric
• D. None of these

Explanation: A conventional manometer compares the process pressure with atmospheric pressure, so its direct reading is gauge pressure.

• A. Low electrical conductivity
• B. Low thermal conductivity
• C. High viscosity index
• D. Low flash point

Explanation: Magnetic flowmeters operate by inducing a voltage in a moving electrically conductive fluid.

• A. Venturimeter
• B. Rotameter
• C. Pitot tube
• D. Hot wire anemometer

Explanation: A rotameter is a variable-area flowmeter: the float rises until the opening area produces a balance between flow forces and the float's…

• A. Based on the principle of Faraday's law
• B. Capable of measuring the flow rate of slurries and electrolytes
• C. All A., B. and C.
• D. Based on the linear relationship between the fluid flow rate and the induced voltage

Explanation: Magnetic flowmeters use Faraday's law, with induced voltage proportional to the conductive fluid velocity and hence flow rate.

• A. Water
• B. Carbon tetrachloride
• C. Ethylene glycol
• D. Paraffin

Explanation: Paraffin has a relatively low density, so a small pressure difference produces a comparatively large liquid displacement in the inclined…

• A. Both B. and C.
• B. Cryogenic flow measurements
• C. Aerospace and in air borne applications
• D. Very limited flow ranges

Explanation: Turbine flow meters are used where accurate measurement is required, including cryogenic service and aerospace or airborne applications.

• A. Weirs
• B. Orificemeter
• C. Mouthpieces
• D. Notches

Explanation: An orificemeter is installed in a closed pipe and measures flow from the pressure drop across an orifice.

• A. Pressure drop across a nozzle
• B. Rotation of a turbine
• C. Variable flow area
• D. Pressure at a stagnation point

Explanation: A rotameter uses a float that rises until the flow force balances its weight, while the tapered tube provides a variable flow area.

• A. V-notch
• B. Rotameter
• C. Orificemeter
• D. Weir

Explanation: A weir is used for measuring relatively large open-channel flow rates, whereas a V-notch is mainly suited to small flows and a rotameter…

• A. Proportional to the square root of
• B. Inversely proportional to the square root of
• C. Proportional to
• D. Inversely proportional to the square of

Explanation: For an orifice, the pressure drop is converted into velocity through Bernoulli's relation, giving Q proportional to √ΔP when the other…

• A. Flow nozzle
• B. Rotameter
• C. Orificemeter
• D. Venturimeter

Explanation: A rotameter measures flow from the position of a float in a tapered tube and is therefore a variable-area meter.

• A. Pitot tube
• B. Kennison nozzle
• C. Vane meter
• D. Open weir

Explanation: A vane meter, or current meter, measures the local velocity of flowing river water; discharge is then obtained from velocity measurements…

• A. Hydrometer
• B. Specific gravity bottle
• C. Pycnometer
• D. Anemometer

Explanation: An anemometer measures fluid velocity, usually that of air or another gas, not liquid density relative to water.

• A. Venturimeter
• B. Magnetic flow meter
• C. Orificemeter
• D. Hot wire anemometer

Explanation: A magnetic flow meter has no obstruction or moving parts and measures conductive liquids using electromagnetic induction.

• A. Rectangular weir
• B. Cipolletti weir
• C. Orifice meter
• D. V-notch

Explanation: An orifice meter is a closed-conduit differential-pressure device and cannot directly measure flow in an open channel.

• A. 0.015
• B. 1.5
• C. 15
• D. 150

Explanation: Atmospheric air has a dynamic viscosity of roughly 0.018 centipoise near room temperature, so 0.015 cP is the closest listed value.

• A. 10
• B. 102
• C. 103
• D. 104

Explanation: One stoke equals 1 cm²/s, which is 10⁻⁴ m²/s. Therefore, 1 m²/s equals 10⁴ stokes.

• A. 1
• B. 10
• C. 100
• D. 1000

Explanation: A water column of 1 mm produces about 9.81 Pa pressure, which is approximately 1 kgf/m².