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May 2023 ChELE > PCI 1,2 > Flashcards

PCI 1,2 Flashcards

1
Q

Which of the following is an undesirable dynamic characteristic of an instrument ?
Reproducibility
Dead zone
Time lag
Static error

A

Time lag

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2
Q

Which of the following is not the triple point of water ?
32°R
273°K
492°R
32°F

A

32°R

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3
Q

Pick out the one which is a first order instrument.
Mercury in glass thermometer (without any covering or air gap).
Bare metallic thermometer.
Bare vapor pressure thermometer.
All (a), (b) and (c).

A

All (a), (b) and (c).

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4
Q

Load cells are used for the measurement of

A

weight

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5
Q

Which of the following is the dynamic characteristics of an instrument ?

A

Fidelity

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6
Q

Pick out the wrong statement.
O2, NO and NO2 exhibit paramagnetic properties as a result of unpaired electrons.
CO2 is the strongest paramagnetic gas.
Paramagnetic susceptibility of gases decreases with temperature.
Paramagnetic susceptibility of gases permits the measurement of their concentration.

A

CO2 is the strongest paramagnetic gas.

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7
Q

The __________ of a vapor pressure thermometer is a functioning element.
pointer
bourdon tube
bulb
none of these

A

pointer

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8
Q

A negative gain margin expressed in decibels means a/an __________ system.

stable
unstable
critically damped
none of these

A

unstable

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9
Q

Thermistor, which has high temperature co-efficient of resistivity, is used as the sensing element in resistance thermometer. It is a/an
insulator
conductor
solid semi-conductor
liquid semi-conductor

A

solid semi-conductor

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10
Q

Flapper nozzle is used in a/an __________ controller.
electronic
hydraulic
pneumatic
none of these

A

pneumatic

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11
Q

Typical specifications for design stipulates the gain margin and phase margin to be respectively
> 1.7 and > 30°
< 1.7 and > 30°
< 1.7 and < 30°
> 1.7 and < 30°

A

> 1.7 and > 30°

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12
Q

Working principle of radiation pyrometer is based on the
Wien’s law
Kirchoffs law
Stafan-Boltzman law
Seebeck effect

A

Stafan-Boltzman law

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13
Q

.
Which of the following relates the emf. generated in a single homogeneous wire to the temperature difference ?
Peltier effect
Thomson effect
Seebeck effect
none of these

A

Thomson effect

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14
Q

Dilute wine was used as a thermometric liquid initially to develop temperature scale. First emperical temperature scale developed was the __________ scale.

A

Fahrenheit

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15
Q

In a single tank system, the transfer function of level to inlet flow rate is
R/TS
R/(TS + 1)
l(TS + l)
1/TS

A

R/(TS + 1)

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16
Q

Which of the following is a desirable characteristic of an instrument ?
High drift
High fidelity
High measuring lag
Poor reproducibility

A

High fidelity

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17
Q

The operation of a rotameter is based on
variable flow area.
rotation of a turbine.
pressure drop across a nozzle.
pressure at a stagnation point.

A

variable flow area.

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18
Q

.
The temperature of tempering oil baths maintained at 400°C during heat treatment of steel is measured by a/an __________ thermocouple.
chromel-alumel
iron-constantan
platinum-platinum/rhodium
none of these.

A

iron-constantan

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19
Q

Instrumentation in a plant offers the advantage of
greater safety of operation
better quality of product
greater operation economy
all (a), (b) and (c)

A

all (a), (b) and (c)

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20
Q

Which of the following temperature measuring instruments need not touch the object whose temperature is being measured ?
Radiation/infrared pyrometer
Filled system thermometer
Mercury in glass thermometer
Thermo electric pyrometer

A

Radiation/infrared pyrometer

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21
Q

Thermal conductivity measurement com-prises the working principle of a
CO2 analyser
polarimeter
spectrometer
chromatograph

A

CO2 analyser

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22
Q

Response of a system to a sinusoidal input is called __________ response.
impluse
unit step
frequency
none of these

A

frequency

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23
Q

The closed loop pole of a stable second order system could be
both real and positive.
complex conjugate with positive real parts.
both real and negative.
one real positive and the other real negative.

A

both real and negative.

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24
Q

Smoke density of the flue gas going out of the chimney is measured by a
polarograph
thermal conductivity meter
photo electric cell
chromatograph

A

photo electric cell

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25
Q

Transfer function of transportation lag is
eTS
e-TS

none of these

A

e-TS

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26
Q

Temperature measuring instruments are standardised mostly with __________ points of pure substances.
melting
boiling
both (a) & (b)
neither (a) nor (b)

A

both (a) & (b)

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27
Q

Pick out the first order system from among the following.
Damped vibrator.
Mercury in glass thermometer kept in boiling water.
Interacting system of two tanks in series.
Non-interacting system of two tanks in series.

A

Mercury in glass thermometer kept in boiling water.

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28
Q

The maximum service temperature for fibre glass used as thermocouple wire insulation material is __________ °C.
250
500
750
1000

A

500

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29
Q

Which of the following controllers has the least maximum deviation ?
P-controller
P-I controller
P-I-D controller
P-D controller

A

P-D controller

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30
Q

Volumetric expansion is the working principle of the __________ thermometers.
mercury in glass
constant volume gas
vapor pressure
bimetallic

A

mercury in glass

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31
Q

.
Which of the following measurements can be made by the measurement of emf ?
pH value
Degree of hydrolysis
Composition of complex ions
All (a), (b) & (c)

A

All (a), (b) & (c)

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32
Q

.
Which of the following measurements can be made by the measurement of emf ?
pH value
Degree of hydrolysis
Composition of complex ions
All (a), (b) & (c)

A

All (a), (b) & (c)

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32
Q

.
Which of the following measurements can be made by the measurement of emf ?
pH value
Degree of hydrolysis
Composition of complex ions
All (a), (b) & (c)

A

All (a), (b) & (c)

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33
Q

A magnetic flowmeter is
based on the principle of Faraday’s law.
capable of measuring the flow rate of slurries and electrolytes.
based on the linear relationship between the fluid flow rate and the induced voltage.
all (a), (b) and (c).

A

all (a), (b) and (c).

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34
Q

Zirconia probe is used for the continuous measurment of __________ flue gases going out of the furnace.
oxygen in
carbon dioxide in
carbon monoxide in
temperature of

A

oxygen in

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35
Q

Strain gage pressure transducers are used to measure __________ pressures.
gage as well as vacuum
absolute as well as differential
both (a) and (b)
neither (a) nor (b)

A

both (a) and (b)

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36
Q

Compositional analysis of __________ is done using mass spectrometer.
an isotope
natural gas
a solid
an alloy

A

an isotope

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37
Q

Compositional analysis of __________ is done using mass spectrometer.
an isotope
natural gas
a solid
an alloy

A

an isotope

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38
Q

The function of a transducer is to
modify the input signal.
amplify the input signal.
convert the primary signal into a more useful quantity, usually an electric impulse.
codify/decodify the input signal.

A

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

39
Q

Nichol’s chart deals with
A.R.vs. phase lag of first order.
A.R. vs. phase lag of second order.
closed loop values vs. open loop values.
frequency response values of controllers.

A

closed loop values vs. open loop values.

40
Q

Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature ?
Platinum-platinum + rhodium.
Iron-constantan.
Chromel-constantan.
All will give the same output.

A

Chromel-constantan.

41
Q

A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if
Kc is reduced.
Kc is increased.
integral control action is introduced.
derivative control action is introduced.

A

Kc is reduced.

42
Q

__________ is undesirable in thermocouples used in industries,
Linear relation of emf to temperature
Corrosion resistance
Oxidation resistance
Non-linear relation of emf to temperature

A

Non-linear relation of emf to temperature

43
Q

Select the correct statement from the following.
The frequency response of a pure capacity process is unbounded.
The phase lag of a pure time delay system decreases with increasing frequency.
The amplitude ratio of a pure capacity process is inversely proportional to frequency.
The amplitude ratio of a pure time delay system increases with frequency.

A

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

44
Q

For an input forcing function, X(t) = 2t2, the Laplace transform of this function is
2/s2
4/s2
2/s3
4/s3

A

4/s3

45
Q

Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a
thermocouple
reistance thermometer
mercury in glass thermometer
vapor pressure thermometer

A

thermocouple

46
Q

The __________ of a vapor pressure thermometer is a secondary element.
pointer
Bourdon tube
bulb
none ofthese

A

Bourdon tube

47
Q

Emf developed by a thermocouple, while measuring a temperature of 600°C is about 5.5 mV. The type of thermocouple used is
chromel-alumel
iron-constantan
platinum-platinum+rhodium
either (a), (b) or (c)

A

platinum-platinum+rhodium

48
Q

Which of the following relates the absorption & evolution of heat at the junctions of a thermocouple to the current flow in the circuit?
Seebeck effect
Peltier effect
Joule heating effect
Thomson effect

A

Peltier effect
Key: abpel

49
Q

In a shell and tube heat exchanger, the flow rate of heating/cooling fluid is the __________ variable.
load
controlled
manipulated
none of these

A

manipulated

50
Q

A non-linear chemical system is exemplified by a/an
isothermal CSTR
mixer
non-isothermal CSTR
none of these

A

non-isothermal CSTR

51
Q

The frequency response of a first order system, has a phase shift with lower and upper bounds given by
- ∞, π/2
-π/2, π/2
-π/2, 0
0, π/2

A

0, π/2

52
Q

Gas chromatography is used for the measurement of
temperature
pressure
concentration
flow rate

A

concentration

53
Q

Which of the following thermocouples can measure the maximum temperature ?
Platinum-rhodium
Tungsten-molybdenum
Chromel-alumel
Iron-constantan

A

Tungsten-molybdenum

54
Q

Radiation pyrometers as compared to thermocouples
has a slower speed of response.
can measure higher temperature.
can’t measure the temperature of moving objects.
is more affected by corrosive atmosphere.

A

can measure higher temperature.

55
Q

iquid flow rate in a small channel is best measured by a/an
weir
pitot tube
vane meter
venturimeter

A

pitot tube

56
Q

Specific gravity of a liquid can not be measured by a/an
anemometer
specific gravity bottle
pycnometer
hydrometer

A

anemometer

57
Q

_________ temperature scale assigns 0° to the ‘ice point’ and 80° to the ‘steam point’.
Celcius
Rankine
Reumur
Farenhite

A

Reumur

58
Q

Dead zone is the
same as time constant.
same as transportation lag.
maximum change in the variable that does not change the reading of the instrument.
none of these.

A

maximum change in the variable that does not change the reading of the instrument.

59
Q

Which of the following thermometers is not suitable for distant reading upto 60 metres?
Vapor pressure thermometer
Mercury in glass thermometer
Constant volume gas thermometer
Resistance thermometer

A

Mercury in glass thermometer

60
Q

.
Degree to which an instrument indicates the changes in measured variable without dynamic error is called its
speed of response
reproducibility
fidielity
static characteristics

A

fidielity

61
Q

Thermistors are made of
ultra pure metals
metal oxides
iron-copper alloys
nickel-chromium alloys

A

metal oxides

62
Q

A barometer measures the __________ pressure.
absolute
gauge
absolute as well as gauge
dynamic

A

absolute

63
Q

Humidity of air can be determined by a
chromatograph
sling psychrometer
mass spectrometer
polarimeter

A

sling psychrometer

64
Q

Thermocouple in a thermal well behaves as a true
first order system.
second order system (overdamped).
multiple first order system.
second order system (underdamped).

A

multiple first order system.

65
Q

The transfer function for a P-D controller is
Kc(1+τD s)
Kc(1 +1/τD s)
Kc τD s
Kc/τD s

A

Kc(1+τD s)

66
Q

Bode diagram is a plot of
log (AR) vs. log (f) and (Φ) vs. log (f).
log (AR) vs. f and log Φ vs.f.
AR vs. log (f) and Φ vs. log (f).
none of these.

A

log (AR) vs. log (f) and (Φ) vs. log (f).

67
Q

Working principle of disappearing filament type optical pyrometer is based on the
Wien’s law
Seebeck effect
Kirchoff’s law
Peltier effect

A

Wien’s law
Key: filament

68
Q

Strain gage uses an electrical conductor wire, which when elastically stretched increases in length and reduces in diameter. Both these dimensional changes result in __________ in the electrical resistance of the wire.
no change
decrease
increase
exponential decrease

A

increase

69
Q

Pick out the wrong statement
Proportional controller is normally used for level control in industrial applications.
CSTR can be considered as a distributed parameter system.
Distributed parameter approach gives partial differential equation.
Non-linear behaviour is exemplified by an on-off controller.

A

CSTR can be considered as a distributed parameter system.

70
Q

Range of hydrogen gas constant volume themometer is __________ °C.
-10 to 20
0 to 100
100 - 500
400 - 1000

A

0 to 100

71
Q

The initial value (t=0) of the unit step response of the transfer function [(s + 1)/(2s + 1)] is
0
1/2
1
2

A

1/2

72
Q

The __________ of a vapor pressure thermometer is a primary element.
pointer
Bourdon tube
bulb
none of these

A

bulb

73
Q

The time constant of a first order process with resistance R and capacitance C is
R + C
R - C
RC
1/RC

A

RC

74
Q

A sinusoidal variation in the input passing through a linear first order system
becomes more oscillatory (frequency increases).
becomes less oscillatory (frequency decreases).
gets amplified (magnitude increases).
gets attenuated (magnitude decreases).

A

gets attenuated (magnitude decreases).

75
Q

Nitrogen gas constant volume thermometer is suitable for measuring a temperature of __________ °C.
0-100
< 0
> 100.
> 50

A

> 100.

76
Q

Pick out the most suitable instrument for measuring temperature in the range of-40 to 425°C.
mercury thermometer
bimetallic thermometer
radiation pyrometer
none of these

A

bimetallic thermometer

77
Q

Accurate temperature measurement performance of a radiation pyrometer can not be affected, if the

enhancement or attentuation of redia-tion occurs in the sighting path.
object and surrounding are at almost the same temperature.
object has varying emissivity.
object is transparent.

A

object and surrounding are at almost the same temperature.

78
Q

Relationship between absorption/evolution of heat at the thermocouple junctions and the current flow in the circuit is given by __________ effect.
Peltier
Thomson
Seebeck
none of these

A

Peltier

79
Q

Configuration of Bourdon spring tube is never made of __________ shape.
circular
semi-circular
helical
spiral

A

circular

80
Q

Thermodynamic celcius scale of temperature measurement is
defined on the basis of melting point of ice and evaporation temperature of water vapor.
defined on the basis of melting point of ice and condensation temperature of water vapor.
having an interval of 100° between ice point to steam point.
both (b) and (c)

A

both (b) and (c)

81
Q

According to Bode stability criterian, a system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at frequency for which phase lag is
0°
45°
90°
180°

A

180

82
Q

In a closed loop system, the process to be controlled is an integrating process with transfer function l/2s. The controller proposed to be used in an integral controller with transfer function 1/T1s. When a step change in set point is applied to such a closed loop system, the controlled variable will exhibit
overdamped response.
underdamped response.
undamped response.
unstable response.

A

underdamped response.

83
Q

Measurement of pressure in ammonia reactor is done by
Bourdon gauge
U-tube manometer
Inclined tube manometer
Pirani guage

A

Bourdon gauge

84
Q

The fluid used in hydraulic controller is
water
steam
air
oil

A

oil

85
Q

Flow rate of a river is measured by a/an
pitot tube
vane meter
kennison nozzle
open weir

A

vane meter

86
Q

Which of the following thermocouple materials does not contain nickel ?
Alumel
Chromel
Constantan
None of these.

A

None of these.

87
Q

Flow rate of those fluids which are insensitive to changes in their density, viscosity or flow velocity profile can be best measured by a
magnetic flowmeter
pitot tube
flow nozzle type flowmeter
turbine flowmeter

A

magnetic flowmeter

87
Q

Flow rate of those fluids which are insensitive to changes in their density, viscosity or flow velocity profile can be best measured by a
magnetic flowmeter
pitot tube
flow nozzle type flowmeter
turbine flowmeter

A

magnetic flowmeter

88
Q

Identify an unbounded input from inputs whose transfer functions are given below
1
1/S
1/S2
1/(S2 + 1)

A

1/S2

89
Q

“A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency.” This is __________ criterion.

A

Bode stability

90
Q

Feed forward controller accounts for the __________ changes.
set point
load
both (a) & (b)
neither (a) nor (b)

A

load

91
Q

Which thermocouple can be used to measure a temperature of around 1400°C ?
Copper-constantan
Aluminium-chromel
Platinum-platinum+rhodium
None of these

A

Platinum-platinum+rhodium

92
Q

Which of the following filled system expansion thermometer has the capability to measure the lowest temperature ?
Mercury in glass thermometer
Mercury in steel thermometer
Alcohol in glass thermometer
Fused metal (Na or K) in steel thermometer

A

Alcohol in glass thermometer

93
Q

Concentration of sugar solution can be determined by the
polarimetry
flame photometry
emission spectroscopy
oscillometry

A

polarimetry

94
Q

In a single tank system, the transfer function of __________ to inlet flow rate is 1/TS+1.
outlet flow rate
level
both (a) & (b)
neither (a) nor (b)

A

outlet flow rate

95
Q

NWhich of the following can not measure a temperature of 1600°C ?
Platinum resistance thermometer
Thermocouple
Photo-electric pyrometer
Radiation pyrometer

A

Platinum resistance thermometer

May 2023 ChELE (11 decks)

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