Process Control

Question 1

Which of the following is an undesirable dynamic characteristic of an instrument?

A. Reproducibility
B. Dead zone
C. Time lag
D. Static error

Answer 1

C. Time lag

Question 2

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 of the above

Answer 2

D. All of the above

Question 3

Load cells are used for the measurement of
A. stress
B. weight
C. strain
D. velocity

Answer 3

B. weight

Question 4

Which of the following is the dynamic characteristics
of an instrument?
A. Reproducibility
B. Sensitivity
C. Dead zone
D. Fidelity

Answer 4

D. Fidelity

Question 5

The ____ of a vapor pressure thermometer
is a functioning element.
A. pointer
B. bourdon tube
C. bulb
D. none of these

Answer 5

A. pointer

Question 6

A negative gain margin expressed in decibels
means a/an system.
A. stable
B. unstable
C. critically damped
D. none of these

Answer 6

B. unstable

Question 7

Thermistor has a high temperature coefficient of
resistivity which is used as the sensing element in
resistance thermometer. It is a/an
A. insulator
B. conductor
C. solid semiconductor
D. liquid semiconductor

Answer 7

C. solid semiconductor

Question 8

Flapper nozzle is used in a/an
controller.
A. electronic
B. hydraulic
C. pneumatic
D. none of these

Answer 8

C. pneumatic

Question 9

Working principle of radiation pyrometer is based on
the
A. Wien’s law
B. Kirchoff’s law
C. Stefan-Boltzman law
D. Seebeck effect

Answer 9

C. Stefan-Boltzman law

Question 10

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

Answer 10

B. Thomson effect

Question 11

Dilute wine was initially used as a thermometric liquid to
develop a temperature scale. The first empirical temperature scale developed
was the ____ scale.
A. Kelvin
B. Centigrade
C. Fahrenheit
D. Reaumer

Answer 11

C. Fahrenheit

Question 12

Which of the following is a desirable characteristic
of an instrument?
A. High drift
B. High fidelity
C. High measuring lag
D. Poor reproducibility

Answer 12

B. High fidelity

Question 13

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

Answer 13

A. variable flow area.

Question 14

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

Answer 14

B. iron-constantan

Question 15

Instrumentation in a plant offers the advantage of
A. greater safety of operation
B. better quality of product
C. greater operation economy
D. all of these

Answer 15

D. all of these

Question 16

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 pyromete

Answer 16

A. Radiation/infrared pyrometer

Question 17

Thermal conductivity measurement comprises the
working principle of a
A. CO2 analyzer
B. polarimeter
C. spectrometer
D. chromatograph

Answer 17

A. CO2 analyzer

Question 18

Response of a system to a sinusoidal input is called_____ response.
A. impulse
B. unit step
C. frequency
D. none of these

Answer 18

frequency

Question 19

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

Answer 19

C. both real and negative.

Question 20

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

Answer 20

C. photo electric celL

Question 21

Temperature measuring instruments are standardized mostly with _____ points of pure substances.
A. melting
B. boiling
C. both (A) & (B)
D. neither (A) nor (B

Answer 21

C. both (A) & (B)

Question 22

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.

Answer 22

B. Mercury in glass thermometer kept in boiling water.

Question 23

The maximum service temperature for fibre glass
used as thermocouple wire insulation material is_____°C
A. 250
B. 500
C. 750
D. 1000

Answer 23

B. 500

Question 24

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

Answer 24

D. P-D controller

Question 25

Volumetric expansion is the working principle of the ______ thermometers. A. mercury in glass B. constant volume gas C. vapor pressure D. bimetallic

Answer 25

A. mercury in glass

Question 26

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 of the above

Answer 26

D. All of the above

Question 27

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 of the above

Answer 27

D. All of the above

Question 28

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 of the above.

Answer 28

D. All of the above.

Question 29

Zirconia probe is used for the continuous measurement of _________flue gases going out of the furnace. A. oxygen in B. carbon dioxide in C. carbon monoxide in D. temperature o

Answer 29

A. oxygen in

Question 30

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)

Answer 30

C. both (A) and (B)

Question 31

Compositional analysis of____ is done using mass spectrometer. A. an isotope B. natural gas C. a solid D. an alloy

Answer 31

A. an isotope

Question 32

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.

Answer 32

C.convert the primary signal into a more useful quantity, usually an electric impulse.

Question 33

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 outpu

Answer 33

C. Chromel-constantan.

Question 34

____ 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

Answer 34

D. Non-linear relation of emf to temperature

Question 35

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

Answer 35

The amplitude ratio of a pure capacity process is inversely proportional to frequency

Question 36

Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a A. thermocouple B. resistance thermometer C. mercury in glass thermometer D. vapor pressure thermometer

Answer 36

thermocouple

Question 37

The of a vapor pressure thermometer is a secondary element. A. pointer B. Bourdon tube C. bulb D. none of these

Answer 37

B. Bourdon tube

Question 38

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)

Answer 38

C. platinum-platinum+rhodium

Question 39

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

Answer 39

B. Peltier effect

Question 40

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

Answer 40

C. manipulated

Question 41

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°

Answer 41

A. >1.7 and >30°