Process Control and Instrumentation MCQs : This section focuses on the "Process Control and Instrumentation". These Multiple Choice Questions (MCQs) should be practiced to improve the Process Control and Instrumentation skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Question 1
In a shell and tube heat exchanger, the flow rate of heating/cooling fluid is the __________ variable.
A. load
B. controlled
C. manipulated
D. none of these
Question 2
Pick out the first order system from among the following.
A. Damped vibrator.
B. Mercury in glass thermometer kept in boiling water.
C. Interacting system of two tanks in series.
D. Non-interacting system of two tanks in series.
Question 3
The __________ of a vapor pressure thermometer is a functioning element.
A. pointer
B. bourdon tube
C. bulb
D. none of these
Question 4
Which of the following controllers has the least maximum deviation ?
A. P-controller
B. P-I controller
C. P-I-D controller
D. P-D controller
Question 5
Strain gage pressure transducers are used to measure __________ pressures.
A. gage as well as vacuum
B. absolute as well as differential
C. both (a) and (b)
D. neither (a) nor (b)
Question 6
Flapper nozzle is used in a/an __________ controller.
A. electronic
B. hydraulic
C. pneumatic
D. none of these
Question 7
Select the correct statement from the following.
A. The frequency response of a pure capacity process is unbounded.
B. The phase lag of a pure time delay system decreases with increasing frequency.
C. The amplitude ratio of a pure capacity process is inversely proportional to frequency.
D. The amplitude ratio of a pure time delay system increases with frequency.
Question 8
A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if
A. Kc is reduced.
B. Kc is increased.
C. integral control action is introduced.
D. derivative control action is introduced.
Question 9
In a single tank system, the transfer function of level to inlet flow rate is
A. R/TS
B. R/(TS + 1)
C. l(TS + l)
D. 1/TS
Question 10
The operation of a rotameter is based on
A. variable flow area.
B. rotation of a turbine.
C. pressure drop across a nozzle.
D. pressure at a stagnation point.
Question 11
Thermistor, which has high temperature co-efficient of resistivity, is used as the sensing element in resistance thermometer. It is a/an
A. insulator
B. conductor
C. solid semi-conductor
D. liquid semi-conductor
Question 12
A magnetic flowmeter is
A. based on the principle of Faraday's law.
B. capable of measuring the flow rate of slurries and electrolytes.
C. based on the linear relationship between the fluid flow rate and the induced voltage.
D. all (a), (b) and (c).
Question 13
Which of the following is a desirable characteristic of an instrument ?
A. High drift
B. High fidelity
C. High measuring lag
D. Poor reproducibility
Question 14
Emf developed by a thermocouple, while measuring a temperature of 600°C is about 5.5 mV. The type of thermocouple used is
A. chromel-alumel
B. iron-constantan
C. platinum-platinum+rhodium
D. either (a), (b) or (c)
Question 15
The temperature of tempering oil baths maintained at 400°C during heat treatment of steel is measured by a/an __________ thermocouple.
A. chromel-alumel
B. iron-constantan
C. platinum-platinum/rhodium
D. none of these.
Question 16
The closed loop pole of a stable second order system could be
A. both real and positive.
B. complex conjugate with positive real parts.
C. both real and negative.
D. one real positive and the other real negative.
Question 17
Response of a system to a sinusoidal input is called __________ response.
A. impluse
B. unit step
C. frequency
D. none of these
Question 18
The function of a transducer is to
A. modify the input signal.
B. amplify the input signal.
C. convert the primary signal into a more useful quantity, usually an electric impulse.
D. codify/decodify the input signal.
Question 19
Which of the following is not the triple point of water ?
A. 32°R
B. 273°K
C. 492°R
D. 32°F
Question 20
Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a
A. thermocouple
B. reistance thermometer
C. mercury in glass thermometer
D. vapor pressure thermometer
Question 21
Which of the following measurements can be made by the measurement of emf ?
A. pH value
B. Degree of hydrolysis
C. Composition of complex ions
D. All (a), (b) & (c)
Question 22
Transfer function of transportation lag is
A. eTS
B. e-TS
Question 23
Load cells are used for the measurement of
A. stress
B. weight
C. strain
D. velocity
Question 24
Smoke density of the flue gas going out of the chimney is measured by a
A. polarograph
B. thermal conductivity meter
C. photo electric cell
D. chromatograph
Question 25
Nichol's chart deals with
A. A.R. vs. phase lag of first order.
B. A.R. vs. phase lag of second order.
C. closed loop values vs. open loop values.
D. frequency response values of controllers.
Question 26
Pick out the wrong statement.
A. O2, NO and NO2 exhibit paramagnetic properties as a result of unpaired electrons.
B. CO2 is the strongest paramagnetic gas.
C. Paramagnetic susceptibility of gases decreases with temperature.
D. Paramagnetic susceptibility of gases permits the measurement of their concentration.
Question 27
Which of the following is the dynamic characteristics of an instrument ?
A. Reproducibility
B. Sensitivity
C. Dead zone
D. Fidelity
Question 28
Which of the following relates the emf. generated in a single homogeneous wire to the temperature difference ?
A. Peltier effect
B. Thomson effect
C. Seebeck effect
D. none of these
Question 29
Which of the following relates the absorption & evolution of heat at the junctions of a thermocouple to the current flow in the circuit?
A. Seebeck effect
B. Peltier effect
C. Joule heating effect
D. Thomson effect
Question 30
Instrumentation in a plant offers the advantage of
A. greater safety of operation
B. better quality of product
C. greater operation economy
D. all (a), (b) and (c)
Question 31
Zirconia probe is used for the continuous measurment of __________ flue gases going out of the furnace.
A. oxygen in
B. carbon dioxide in
C. carbon monoxide in
D. temperature of
Question 32
__________ is undesirable in thermocouples used in industries,
A. Linear relation of emf to temperature
B. Corrosion resistance
C. Oxidation resistance
D. Non-linear relation of emf to temperature
Question 33
For an input forcing function, X(t) = 2t2, the Laplace transform of this function is
A. 2/s2
B. 4/s2
C. 2/s3
D. 4/s3
Question 34
Typical specifications for design stipulates the gain margin and phase margin to be respectively
A. > 1.7 and > 30°
B. < 1.7 and > 30°
C. < 1.7 and < 30°
D. > 1.7 and < 30°
Question 35
Dilute wine was used as a thermometric liquid initially to develop temperature scale. First emperical temperature scale developed was the __________ scale.
A. Kelvin
B. Centigrade
C. Fahrenheit
D. Reaumer
Question 36
The __________ of a vapor pressure thermometer is a secondary element.
A. pointer
B. Bourdon tube
C. bulb
D. none ofthese
Question 37
Pick out the one which is a first order instrument.
A. Mercury in glass thermometer (without any covering or air gap).
B. Bare metallic thermometer.
C. Bare vapor pressure thermometer.
D. All (a), (b) and (c).
Question 38
Compositional analysis of __________ is done using mass spectrometer.
A. an isotope
B. natural gas
C. a solid
D. an alloy
Question 39
Thermal conductivity measurement com-prises the working principle of a
A. CO2 analyser
B. polarimeter
C. spectrometer
D. chromatograph
Question 40
Which of the following is an undesirable dynamic characteristic of an instrument ?
A. Reproducibility
B. Dead zone
C. Time lag
D. Static error
Question 41
The maximum service temperature for fibre glass used as thermocouple wire insulation material is __________ °C.
A. 250
B. 500
C. 750
D. 1000
Question 42
Temperature measuring instruments are standardised mostly with __________ points of pure substances.
A. melting
B. boiling
C. both (a) & (b)
D. neither (a) nor (b)
Question 43
Working principle of radiation pyrometer is based on the
A. Wien's law
B. Kirchoffs law
C. Stafan-Boltzman law
D. Seebeck effect
Question 44
Which of the following temperature measuring instruments need not touch the object whose temperature is being measured ?
A. Radiation/infrared pyrometer
B. Filled system thermometer
C. Mercury in glass thermometer
D. Thermo electric pyrometer
Question 45
Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature ?
A. Platinum-platinum + rhodium.
B. Iron-constantan.
C. Chromel-constantan.
D. All will give the same output.
Question 46
A negative gain margin expressed in decibels means a/an __________ system.
A. stable
B. unstable
C. critically damped
D. none of these
Question 47
Volumetric expansion is the working principle of the __________ thermometers.
A. mercury in glass
B. constant volume gas
C. vapor pressure
D. bimetallic