Food Processing Unit Operations Questions and Answers for Freshers on “Pressure Measurement in a Fluid”.
1. Manometer is used for measuring __________
a) pressure
b) speed
c) Fathometer
d) density
Answer: a
Clarification: Manometer is used for measuring pressure. Tachometer is used for measuring speed. Hydrometeris used for measuring density. Fathometeris used for measuring ocean depth.
2. Which instrument is used to measure medium pressure?
a) Bourdon tube pressure gauges
b) Barometric sensor
c) Piezoelectric pressure sensor
d) Piezoresistive pressure sensor
Answer: a
Clarification: Bourdon tube pressure gauges are widely used to measure medium to high pressure. The range of pressure it can detect is from 600mbar to 4000 bar. The measuring unit consists of curved tube with circular, spiral or coiled shape called as bourdon tube.
3. Which pressure instrument is used inweather networks?
a) Bourdon tube pressure gauges
b) Barometric sensor
c) Piezoelectric pressure sensor
d) Piezoresistive pressure sensor
Answer: b
Clarification: Barometric sensoris used in weather networks. These sensors measure the fluctuations in the pressure exerted by atmosphere. They are enclosed with a data logger and is well protected from precipitation, water ingress and condensing humidity.
4. _____________ measure dynamic pressure.
a) Bourdon tube pressure gauges
b) Barometric sensor
c) Piezoelectric pressure sensor
d) Piezoresistive pressure sensor
Answer: c
Clarification: Piezoelectric pressure sensors measure dynamic pressure. The dynamic pressure measurements include the blast, ballistics, turbulence and engine combustion. These sensors have the ability to measure quasi static pressures. They are fast response, extended ranges, ruggedness and high stiffness
5. Which instrument uses the change in electric resistance to measure the pressure?
a) Bourdon tube pressure gauges
b) Barometric sensor
c) Piezoelectric pressure sensor
d) Piezoresistive pressure sensor
Answer: d
Clarification: Piezoresistive pressure sensoruses the change in electric resistance of a material when stretched to measure the pressure. Due to the simple design and robustness, this instrument is used for wide range of applications. These are used for gauge, absolute and relative pressure measurement in both high and low pressure applications.
6. Which of the following statements about pressure transmitters are correct?
Statement 1: It contains pressure sensor and signal conditioner.
Statement 2:There are four main types of pressure transmitters.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: b
Clarification: Pressure transmitters contain pressure sensor and a signal conditioner to amplify the weak electrical signals that are sent through the pressure sensors for measuring the pressure. There are four main types of pressure transmitters. They are absolute, gauge, differential pressure, and multivariable.
7. Which of the following statements about vacuum gauges are correct?
Statement 1: Thermal vacuum gauges sense the cooling effect of a heated filament.
Statement 2: Thermal vacuum gauges designed to measure high pressures.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: a
Clarification: The vacuum gauges designed to measure very low pressures or in a vacuum.The vacuum gauges sense the cooling effect of a heated filament on the gases in the vacuum chamber being measured. It consists of heated thin wire. These resemble as thermal flow meters, where heated wire is placed into the flow steam and infer the flow by measuring the speed with which heat is dissipated. The vacuum gauges sense the cooling effect of a heated filament on the gases in the vacuum chamber being measured.
8. One pascal is equivalent to _______ of force applied over an area of one meter squared.
a) one newton
b) 100 newton
c) 1000 newton
d) 10 newton
Answer: a
Clarification: One pascal is equivalent to one newton of force applied over an area of one meter squared. The pascal is the unit of pressure and it is named after the scientist Blaise Pascal.
9. The manomeric fluid density should be ______than that of flowing fluid.
a) greater
b) smaller
c) equal
d) very small
Answer: a
Clarification: The manometer is also called as wet meter. The density of the manomeric fluid should be greater than that of flowing fluid. Mercury can be used because it has a high density and therefore manometer size is minimized.
10. What is relation between PSI and Bar?
a) 1 Bar = 14.5 Psi
b) 1 Bar = 20 Psi
c) 1 Bar = 201 Psi
d) 1 Bar = 1 Psi
Answer: a
Clarification: For all pressure unit conversions, Psi (pounds per square inch) is 1 pound of force per square inch. Bar is equal to the atmospheric pressure at sea level.