Food Processing Unit Operations Multiple Choice Questions on “Fluid Flow Applications – Pumps and Fans”.
1. In a __________ pump, the fluid is drawn into pump and is then forced through outlet.
a) positive displacement
b) jet
c) airlift
d) propeller pumps
Answer: a
Clarification: In a positive displacement pump, the fluid is drawn into pump and is then forced through outlet. These pumps can develop high pressure heads but they cannot stand blockages and throttling in the discharge outlet.
2. In _________pumps, the energy of the fluid is converted into velocity energy.
a) positive displacement
b) jet
c) airlift
d) propeller pumps
Answer: b
Clarification: In jet pumps, a high velocity jet is produced in a nozzle where the energy of the fluid is converted into velocity energy. Jet pumps have low efficiencies but they have no moving parts and therefore have low initial costs.
3. Which of the following pumps can be used as vacuum pumps?
a) Positive displacement
b) Jet
c) Airlift
d) Propeller pumps
Answer: b
Clarification: The jet pumps are used as vacuum pumps.A high velocity jet converts the energy of the fluid into velocity energy in the nozzle. This produces a low pressure area causing the surrounding fluid to be sucked into the pipe.
4. Are these statements about the propeller pumps true?
Statement 1: Propellers are used to impart energy to the fluids.
Statement 2: They have low efficiency.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: a
Clarification: Propellers are used to impart energy to the fluids. They are widely used to mix the contents of tanks and in pipes and convey the fluids. They have high efficiency and are used for low heads.
5. The _________pump converts rotational energy of the fluid to velocity and pressure.
a) centrifugal
b) jet
c) airlift
d) propeller pumps
Answer: a
Clarification: The centrifugal pumps convert rotational energy of the fluid to velocity and pressure. The fluid to be pumped is taken at the center of the rotor and is passed along the spinning rotor thus producing rotational energy. This rotational energy is then converted into velocity and pressure at the periphery of the disc.
6. Which of the following statements about airlift pumps are correct?
Statement 1: In airlift pumps, the air is introduced above a liquid in pressure level and that pressure is used to discharge the liquid.
Statement 2: Airlift pumps are used to convey powders in fluidized form.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: b
Clarification: In airlift pumps, the air is introduced above a liquid in pressure level and that pressure is used to discharge the liquid. In case of powders, air is blown up through a bed of powder to convey it in the fluidized form. They are convenient for the materials which cannot be passed easily through valves and ports.
7. What is significance of fan law?
a) It deals with pressure and velocity of the fan
b) It deals with pressure and power consumption of the fan
c) It deals with performance of the fan and power consumption of the fan
d) It deals with performance of the fan velocity of the fan