INDIABIX-PROCESS CONTROL AND INSTRUMENTATION Flashcards by Vince Rafael Candelaria

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

Time lag

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

32°R

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Load cells are used for the measurement of
stress
weight
strain
velocity

weight

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Which of the following is the dynamic characteristics of an instrument ?
Reproducibility
Sensitivity
Dead zone
Fidelity

Fidelity

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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.

-CO2 is the strongest paramagnetic gas.

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Which is the strongest paramagnetic gas?
A. CO2
B. O2
C. NO
D. NO2

B. O2

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

pointer

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

unstable

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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

solid semi-conductor

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

pneumatic

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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°

> 1.7 and > 30°

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

Stafan-Boltzman law

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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

Thomson effect

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

Fahrenheit

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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

R/(TS + 1)

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

High fidelity

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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.

variable flow area.

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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.

iron-constantan

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

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

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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

Radiation/infrared pyrometer

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Thermal conductivity measurement comprises the working principle of a _____.
CO2 analyzer
polarimeter
spectrometer
chromatograph

CO2 analyzer

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

frequency

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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.

both real and negative.

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

photo electric cell

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Transfer function of transportation lag is
e^TS
e^-TS
1/Ts+1
none of these

e^-TS

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

both (a) & (b)

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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.

Mercury in glass thermometer kept in boiling water.

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

500

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

P-D controller

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

mercury in glass

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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)

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

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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).

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

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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

oxygen in

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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)

both (a) and (b)

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

an isotope

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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.

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

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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.

closed loop values vs. open loop values.

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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.

Chromel-constantan.

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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.

Kc is reduced.

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

Non-linear relation of emf to temperature

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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.

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

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

thermocouple

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

Bourdon tube

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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)

platinum-platinum+rhodium

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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

Peltier effect

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

manipulated

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

non-isothermal CSTR

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

concentration

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

Tungsten-molybdenum

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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.

can measure higher temperature.

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

pitot tube

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

anemometer

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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.

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

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

Mercury in glass thermometer

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

fidelity

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

metal oxides

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

absolute

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

sling psychrometer

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

multiple first order system.

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

Wien’s law

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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

increase

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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.

CSTR can be considered as a distributed parameter system.

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

0 to 100

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

1/2

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

bulb

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

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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).

gets attenuated (magnitude decreases).

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

> 100

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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

bimetallic thermometer

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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.

object and surrounding are at almost the same temperature

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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

Peltier

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

circular

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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)

both (b) and (c)

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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°

180°

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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.

underdamped response.

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underdamped response.

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

Bourdon gauge

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The fluid used in hydraulic controller is ___
water
steam
air
oil

oil

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

vane meter

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

None of these.

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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

magnetic flowmeter

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

1/S2

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“A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency.” This is __________ criterion.
Bode stability
Nyquist
Routh stability
none of these

Bode stability

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

load

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

Platinum-platinum+rhodium

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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

Alcohol in glass thermometer

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

polarimetry

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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)

outlet flow rate

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

Platinum resistance thermometer

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Paramagnetism method is not used for the composition determination of __________ in gases.

oxygen
oxides of nitrogen
carbon dioxide
any of these

carbon dioxide

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Pressure of 0.0001 absolute psi can be measured by __________ gauge.

Mcloid
Pirani
thermocouple
none of these

Mcloid

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Pirani gauge is used for the measurement of

very high pressure.
high vacuum.
liquid level under pressure.
liquid level at atmospheric pressure

high vacuum.

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__________ thermometer can not measure sub-zero (< 0° C) temperature,

Mercury in glass
Bimetallic
Vapor pressure
Resistance

Bimetallic

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Liquid argon level in a pressurised storage tank (at 3 kg/cm2 ) is measured by a/an

gage glass
external float gage
differential pressure gage
none of these

differential pressure gage

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What is the dynamic error in a critically damped second order instrument for a ramp input (At) ?

0.5 AT
2 AT
AT
1.5 AT

2 AT

The deflection of the free end of the bimetallic strips in a bimetallic thermometer with temperature is nearly

linear
non-linear
parabolic
hyperbolic

linear

Alphatron measures pressure __________ microns.

< 1
< 3
> 3
< 0.1

> 3

What is the ratio of output amplitude to input amplitude for a sinusoidal forcing function in a first order system ?

1
>1
< 1
none of these

< 1

The term analogous to the electrical current in a thermal system is the

temperature difference
heat flow rate
heat content in the system
none of these

heat flow rate

Reset rate is the another term used for __________ time.

dead
integral
derivative
none of these

integral

Continuous measurement of moisture in paper is done by

sling psychrometer.
hair-hygrometer.
weighing.
high resistance Wheatstone’s bridge circuit.

high resistance Wheatstone’s bridge circuit.

Psychrometer determines the

humidity of gases
moisture content of solids
water of crystallisation
hygroscopic nature of solids

humidity of gases

A mercury barometer measures the __________ pressure.

atmospheric
gauge
vacuum
absolute

atmospheric

Positioning controllers are used for

low loads
temperature changes
high loads
flow rate changes

high loads

The response of two tanks of same size and resistance in series is

under damped
critically damped
over damped
none of the above

critically damped

Which of the following is a ‘contact’ pyrometer ?

resistance pyrometer
optical pyrometer
radiation pyrometer
infra red pyrometer

resistance pyrometer

Measurement of sub-zero Celcius temperature in industry is done most commonly by

thermocouples
resistance thermometers
gas thermometers
bi-metallic thermometers

resistance thermometers

Use of I-control along with P-control facilitates

elimination of offset
reduction of offset
reduction of stability time
none of these

elimination of offset

Liquid discharge from a tank or reservoir can not be measured by

orificemeters
weirs
mouthpieces
notches

orificemeters

__________ are analysed using a polarograph.

Isotonic solutions
Solids
Liquids
Gases

Solids

Which of the following judges the accuracy of an instrument ?

Dead zone
Drift
Static error
None of these

Static error

On-off controllers are normally used for

low loads
temperature changes
flow rate changes
none of these

low loads

Magnetic flowmeters are generally not used for the velocity/flow measurement of hydrocarbons due to their

low thermal conductivity.
low electrical conductivity.
high viscosity index.
low flash point.

low electrical conductivity.

Which of the following controllers has maximum offset ?

P-controller
P-I controller
P-D controller
P-I-D controller

P-controller

Pressure of 0.01 psi (absolute) can be measured by __________ gauge.

ionisation
Pirani
Mcloid
none of these

Mcloid

Which of the following does not figure in the list of seven substances selected for international temperature scale?

Ice (F.P) and steam (B.P)
Oxygen and sulphur (B.P)
Antimony and silver (F.P)
Zinc (B.P) and mercury (F.P)

Zinc (B.P) and mercury (F.P)

A constant volume gas thermometer employing __________ is used to measure sub-zero (i.e., < 0° C) temperature.

helium
hydrogen
nitrogen
none of these

helium

A constant volume gas thermometer employing __________ is used to measure sub-zero (i.e., < 0° C) temperature.

helium
hydrogen
nitrogen
none of these

helium

pH meter has

one cell
two cells
three cells
no cell

two cells

Routh test

a) criterion provides information about the actual location of roots.
b) cannot be used to test the stability of a control system containing transportation lag.
c) criterion is not applicable to systems with polynomial characteristic equation.
d) can not determine as to how many roots of the characteristics equation have positive real roots.

b) cannot be used to test the stability of a control system containing transportation lag.

When a bare thermocouple is covered by a protective sheath, the response becomes

a) faster and oscillatory.
b) faster and non-oscillatory.
c) slower and oscillatory.
d) slower and non-oscillatory.

d) slower and non-oscillatory.

Bode diagram are generated from output response of the system subjected to which of the following input?

Impulse
Step
Ramp
Sinusoidal

Sinusoidal

Which of the following is not a differential pressure flow meter ?

Rotameter
Flow nozzle
Orificemeter
Venturimeter

Rotameter

Working principle of mercury in glass thermometer is based on volumetric expansion of mercury with increase in temperature. Which of the following undergoes minimum volumetric expansion for a given temperature change ?

Water
Mercury
Methyl alcohal
Carbon-tetrachloride

Mercury

A photo electric device in which the resistance of the metal is directly proportional to the light striking on it, is known as photo-conductive cell. Photoelectric transducers are used for the measurement of those parameters, which can be used to produce variation in

light intensity
current
flux density
voltage

light intensity

A typical example of a physical system with under damped characteristic is a

a) U-tube manometer.
b) spring loaded diaphragm valve.
c) CSTR with first order reaction.
d) thermocouple kept immersed in a liquid filled thermowell.

b) spring loaded diaphragm valve.

An aneroid barometer measures the __________ pressure.

atmospheric
absolute
vacuum
gage

absolute

Thermal wells are used in the temperature measurement to

a) guard against corrosive and oxidising action on thermocouple materials
b) reduce measuring lag.
c) increase the fidelity.
d) increase the sensitivity.

a) guard against corrosive and oxidising action on thermocouple materials

The offset introduced by proportional controller with gain Kcin response of first order system can be reduced by

reducing value of Kc.
introducing integral control.
introducing derivative control.
none of the above.

introducing integral control.

A system with a double pole at the origin is unstable since the corresponding term in the time domain

is a constant.
grows exponentially with time.
grows linearly with time.
decays linearly with time.

grows linearly with time.

To increase the speed of response of a pressure spring liquid or gas expansion thermometer, the clearance space between the thermometer bulb and the thermal well should not be filled with

air
a metal powder or graphite
oil
mercury

air

In an exothermic chemical reactor, the manipulated variable is the flow rate of

coolant
reactants
product
none of these

coolant

Thermal conductivity based continuous flue gas analyser makes use of varying thermal conductivity of the constituents of flue gases. Which of the following constituents of flue gases has the maximum thermal conductivity ?

CO2
N2
O2
CO

CO2

Emf generated in a thermocouple depends on the temperature

a) of cold junction only.
b) of hot junction only.
c) difference between hot and cold junctions.
d) difference between cold junction and atmospheric temperature.

c) difference between hot and cold junctions.

Working principle of mercury in glass thermometer is based on the __________ of mercury with increase in temperature.

increase of pressure
increase of thermal conductivity
volumetric expansion
differential linear expansion

volumetric expansion

Working principle of mercury in glass thermometer is based on the __________ of mercury with increase in temperature.

increase of pressure
increase of thermal conductivity
volumetric expansion
differential linear expansion

volumetric expansion

Radiation thermometer can not measure the temperature

a) inside a pressure vessel.
b) of an object without coming in contact with it.
c) of liquid oxygen.
d) of moving objects at high temperature.

c) of liquid oxygen.

Temperature measurement by optical pyrometer is done above __________ point, which is 1063°C.

antimony
gold
silver
nickel

gold

Continuous flue gas analyser makes use of paramagnetic properties of some of its constituents, which move towards the strongest part of the magnetic field thus displacing diamagnetic gases. Which of the following gases is diamagnetic ?

CO2
O2
NO
NO2

CO2

Dilatometer is used to measure

a) stress
b) strain
c) deflection
d) contraction/expansion due to changes in temperature

d) contraction/expansion due to changes in temperature

Mass spectrometer is used for the composition analysis of

alloys
solids
isotopes
none of these

isotopes

_________ stability method uses open loop transfer function.

Nyquist
Mikhalov
Ruth
none of these

Nyquist

A pyranometer is an instrument used for measuring the

beam radiation.
global radiation.
bright sunshine period.
none of these.

global radiation.

All the thermocouples used for temperature measurement use dissimilar metal

strips
bars
wires
beads

wires

Composition of alloys can be determined by

polarograph
chromatograph
refractrometer
none of these

polarograph

Optical activity of a solution can be determined using a

polarimeter
polarograph
dilatometer
refractrometer

polarimeter

Stability of a control system containing a transportation lag can be best analysed by

Routh test
root locus methods
frequency response methods
none of these

frequency response methods

Time constant is the
a) time taken by the controlled variable to reach 63.2% of its full change.
b) same as transportation lag.
c) same as dead time.
d) time required by the measured variable to reach 63.2% of its ultimate change.

a) time taken by the controlled variable to reach 63.2% of its full change.

Mercury manometer (U-tube type) exemplifies a __________ order system.

zero
first
second
third

second

Working principle of bimetallic thermometers is difference in linear co-efficient of thermal expansion of two strips of different metals welded together. Which of the following has the maximum thermal co-efficient of linear expansion?

Nickel
Brass
Chromel
Invar

Brass

Which of the following is not a second order instrument ?

Mercury in glass thermometer with covering.
Bare mercury in glass thermometer.
Pressure gauge with one bellow, two tubes and a tank.
None of these

Bare mercury in glass thermometer.

Small furnace draught is accurately measured by an inclined tube manometer, in which the manometric liquid used most commonly is

water
carbon tetrachloride
paraffin
ethylene glycol

paraffin

A simple pitot tube measures the

average velocity
maximum velocity
point velocity
static pressure

static pressure

A simple pitot tube measures the

average velocity
maximum velocity
point velocity
static pressure

static pressure

For a feed back control system to be stable, the

a) roots of the characteristic equation should be real.
b) poles of the closed loop transfer function should lie in the left half of the complex plane.
c) Bode plots of the corresponding open loop transfer function should monotoni-cally decrease.
d) poles of the closed loop transfer function should lie in the right half of the complex plane.

b) poles of the closed loop transfer function should lie in the left half of the complex plane.

__________ controller has the maximum stabilising
time.

P
PD
PI
PID

Out of the following temperature measuring instruments, the measurement accuracy will be minimum for the

mercury in glass thermometer.
optical pyrometer.
iron-constantan thermocouple.
alcohol filled thermometer.

optical pyrometer.

Stalagmometer is used for the measurement of

kinematic viscosity
surface tension
refractive index
optical activity

surface tension

Stalagmometer is used for the measurement of

kinematic viscosity
surface tension
refractive index
optical activity

surface tension

Liquid levels in autocalves are measued by

simple float
differential float type manometer
glass gauge
none of these

differential float type manometer

E.m.f. generated by thermocouples is of the order of

millivolts
microvolts
volts
kilo volts

millivolts

A pyrheliometer is an instrument used for measuring the

bright sunshine period.
beam radiation.
diffuse radiation.
none of these.

beam radiation.

Flow rate through an orifice is __________ the pressure differential.

proportional to
inversely proportional to the square root of
proportional to the square root of
inversely proportional to the square of

proportional to the square root of

_________ is the static characteristics of an instrument,

Response
Tine lag
Drift
dynamic error

Drift

Emission spectroscopy is used for

solids and metal analysis.
determining water purity.
determination of CO2 in gases.
NOxdetermination.

solids and metal analysis.

Gas analysis is commonly done using the

thermal conductivity cell
X-ray diffraction
mass spectrometer
emission spectrometer

thermal conductivity cell

Thermal conductivity measurement is used for the determination of

O2 percentage in the flue gas.
specific gravity of petrofuels.
composition of an alloy.
CO2 percentage in the flue gas.

CO2 percentage in the flue gas.

Presence of a small amount of water in the organic systems can be determined by the __________ method.

electrical conductivity
polarimetry
emission spectroscopy
dielectric constant end loss factor

dielectric constant end loss factor

Thermal conductivity cell is the primary element of a/an __________ analyser.

oxygen
carbon dioxide
carbon monoxide
sulphur dioxide

carbon dioxide

Zirconia probe is used for the measurement of

humidity of air.
% CO2 in flue gas.
% O2 in flue gas.
speed of a submarine.

% O2 in flue gas.

_________ type of element is normally not used in the bimetallic thermometers.

Flat spiral
Bourdon tube
Single helix
Multiple helix

Bourdon tube

Process degree of freedom indicates __________ number of controllers to be used.

the maximum
the minimum
both maximum and the minimum
nothing about the

the maximum

Polarograph is meant for the analysis of

gaseous mixture
miscible liquids
solids
isotopes

solids

Which of the following fluid flow measuring devices can measure the largest flow rate ?

V-notch
Rotameter
Orificemeter
Weir

Weir

In a shell and tube heat exchanger, the inlet temperature of heating/cooling fluid is the __________ variable.

load
manipulated
controlled
none of these

load

Polarisation of light forms the working principle of a

polarimeter
polarograph
chromatograph
spectrometer

polarimeter

Thermal wells used in temperature measurements should have

very thick walls.
low emissivity.
polished surface.
high transmissivity of radiation.

high transmissivity of radiation.

Which of the following flow-metering instru-ments is an areameter ?

Venturimeter
Rotameter
Pitot tube
Hot wire anemometer

Rotameter

Out of the following themocouple wire insulating material, the highest temperature rating is for

teflon
ceramic fibre
asbestos
fibre glass

ceramic fibre

Which is the most suitable instrument for measuring pressure below 3 microns ?

Mcleoid gauge
Alphatron
Ionisation gauge
Bourdon guage

Ionisation gauge

Non-metallic diaphragm used as pressure sensor in instruments is generally made of

teflon
synthetic rubber
bakelite
thick paper

synthetic rubber

Response of a linear control system for a change in set point is called

frequency response
transient response
servo problem
regulator problem

servo problem

Hot wire anemometer is used for the measurement of

flow rates of fluids.
flow rates of granular solids.
very high temperature.
thermal conductivity of gases.

flow rates of fluids.

Which of the following thermocouples has the widest temperature measurement range ?

Iron-constantan
Chromel-alumel
Copper-constantan
Platinum-platinum/rhodium

Platinum-platinum/rhodium

Temperature control of an exothermic chemical reaction taking place in a CSTR is done with the help of cooling water flowing in a jacket around the reactor. The types of valve and controller action to be recommended are

a) air to open valve with the controller direct acting.
b) air to close valve with the controller indirect acting.
c) air to open valve with the controller indirect acting.
d) air to close valve with the controller direct acting.

c) air to open valve with the controller indirect acting.

Bourdon tube is never made of

phosphor bronze
monel metal
stainless steel
cast iron

cast iron

“An emf of the order of mV is generated when two solutions of different hydrogen ion concentration are separated by a thin glass wall”. This is the working principle of a

pH meter
polarimeter
chromatograph
polarograph

pH meter

The term analogous to voltage in a single tank system is the

heat content of the system.
liquid volume in the tank.
flow rate.
level of liquid.

level of liquid.

In a shell and tube heat exchanger, the outlet temperature of heating/cooling fluid is the __________ variable.

load
manipulated
controlled
none of these

controlled

Mcleoid gauge is used to measure the

point velocity
flow rate
vacuum
pressure

vacuum

Thermocouple is suitable for measuring

liquid temperatures only.
very high temperatures only.
very low temperatures only.
both high and low temperatures.

both high and low temperatures.

Bimetal strips are not used in

bimetallic thermometers.
thermocouples.
thermostats.
relays for opening & closing of electrical circuits.

thermocouples.

When the damping co-efficient (ξ) is unity, the system is

Overdamped.
Critically damped.
Underdamped.
Highly fluctuating.

Critically damped.

A non-linear system will have __________ steady state values.

one
more than one
two
three

more than one

Which of the following is not a variable area flow meter?

Piston type meter
Rotameter
Magnetic flow meter
Orifice and tapered plug meter

Magnetic flow meter

Sub-zero temperature (< 0°C) can be measured by a constant volume gas thermometer employing

helium
nitrogen
hydrogen
none of these

helium

_________ is an example of distributed parameter system

Tubular reactor
CSTR
On-off controller
none of these

Tubular reactor

Maximum differential pressure in liquid manometer is __________ psi.

20
30
40
50

Phase margin is equal to

180° - phase lag
phase lag - 180°
phase lag + 180°
phase lag + 90°

180° - phase lag

Flow rate measurement of hostile acids and alkalis can be most suitably done by a/an

venturimeter
orificemeter
magnetic flow meter
hot wire anemometer

magnetic flow meter

Compositional analysis of flue gas coming out of a furnace in respect of O2 and CO2% can be continuously done by a/an

orsat apparatus
thermal conductivity cell
zirconia probe
chromatograph

thermal conductivity cell

Thermisters which have a very high temperature co-efficient of resistivity belong to the class of solid called

dielectrics
insulators
semi conductors
conductors

semi conductors

The pressure sensing element of elastic type pressure gauge is never made in the form of a

bellow
diaphragm
strip
Bourdon tube

strip

Liquid flow rate in an open channel can not be measured by a/an

orifice meter
cipolletti weir
rectangular weir
V-notch

orifice meter

The unit of ‘time constant’ of a system is the same as that of

velocity
time
(time)^-1
none of these

time

Which of the following filled system expansion thermometers has the lowest positive temperature measurement capability ?

Mercury in glass thermometer.
Alcohol in glass thermometer.
Fused metal (Na or K) in steel thermometer.
Nitrogen in steel thermometer.

Alcohol in glass thermometer.

Cascade control means

feed forward control.
more than one feed-back loop.
on-off control.
one feed-back loop.

more than one feed-back loop.

The level of a liquid under pressure can be determined using

bubbler system
differential pressure manometer
diaphragm box system
air-trap system

differential pressure manometer

Which of the following is never used as an element of industrial resistance thermometer ?

Lead
Nickel
Copper
30% iron + 70% nickel

Lead

Which of the following shows maximum dip effect (indicating reverse direction of temperature change) ?

Mercury thermometer
Radiation pyrometer
Bimetallic thermometer
Thermocouple

Mercury thermometer

A stable system is the one

a) for which the output response is bounded for all bounded input.
b) which exhibits an unbounded response to a bounded input
c) which satisfies the conditions for a servo problem.
d) none of these.

a) for which the output response is bounded for all bounded input.

Meleoid gauge measures the __________ pressure.

positive
sub-atmospheric
very high
atmospheric

sub-atmospheric

Change of angle of refraction with composition comprises the working principle of a

polarimeter
polarograph
spectrometer
refractrometer

refractrometer

Flame photometry is used for the determination of compositional analysis of

solids
alkali metals
natural gas
isotopes

alkali metals

Which of the following is not a composition measuring instrument ?

Thermal conductivity cell
Mass spectrometer
Polarograph
Hot wire anemometer

Hot wire anemometer

On-off control which is a special case of proportional control, has a band width of about __________ percent.

100
75
25
0

The thermal emf-temperature relationship of most thermocouples is

linear
parabolic
exponential
square root

parabolic

Which is the strongest paramagnetic gas?

CO2
O2
NO
NO2

In Bode plot, A.R. vs. w is plotted on a/an __________ graph paper.

log-lag
triangular
ordinary
semi-log

log-lag

Stroboscope is used for the measurement of

rpm of a flywheel
frequency of light
depression of freezing point
liquid level under pressure

rpm of a flywheel

In second order underdamped system,

decay ratio = overshoot
decay ratio = (overshoot)^2
overshoot increases for increasing damping co-efficient.
large damping co-efficient means smaller damping.

decay ratio = (overshoot)^2

Dome temperature of blast furnace stove is most accurately measured by a

radiation pyrometer.
platinum-platinum/rhodium thermocouple.
iron-constantan thermocouple.
platinum resistance thermometer.

platinum-platinum/rhodium thermocouple.

Phase lag of the sinusoidal response of a first order system is

120°
30°
180°
90°

90°

Continuous measurement of moisture content of paper in paper industry is done by measuring the

thermal conductivity through the paper
electrical resistance through the paper
magnetic susceptibility
none of these

electrical resistance through the paper

Thermal well made of __________ gives the fastest speed of response, while measuring temperature by thermocouples.

steel
vycor (a glass)
nichrome
inconel

vycor (a glass)

Pick out the wrong statement.

a) There is no transfer lag for a single first order system.
b) Stirred tank with a water jacket exemplifies an interacting system.
c) Transfer lag is a characteristics of all higher order systems (other than first order systems).
d) Transfer lag decreases as the number of stages decreases.

d) Transfer lag decreases as the number of stages decreases.

Working principle of mercury in glass thermometer is

volumetric expansion.
pressure rise with temperature.
linear expansion.
none of these.

volumetric expansion.

The frequency at which maximum amplitude ratio is attained is called the __________ frequency.

corner
resonant
cross-over
natural

resonant

If response of a control system is to be free of offset and oscillation, the most suitable controller is

proportional controller.
proportional-derivative(PD)controller.
proportional-integral (PI) controller.
proportional integral-derivative (PID) controller.

proportional integral-derivative (PID) controller.

A manometer measures the __________ pressure.

atmospheric
absolute
gauge
none of these

gauge

Minute depression of freezing point of a liquid solvent on addition of a solid solute can be best measured by a

Beckman thermometer
dilatometer
mercury thermometer
bimetallic thermometer

Beckman thermometer

Temperature of __________ can not be measured by an optical or radiation pyrometer.

hot blast (air) from stoves
molten slag flowing out of blast furnace
combustion space in boilers
rotary limestone calcination kiln

hot blast (air) from stoves

Gain margin is equal to the

amplitude ratio
reciprocal of amplitude ratio
gain in P controller
gain in P-I controller

reciprocal of amplitude ratio

In Bode plot, Φ vs ω is plotted on a/an __________ graph paper.

log-log
ordinary
semi-log
triangular

log-log

For two non-interacting first order systems connected in series, the overall transfer function is the __________ of the individual transfer functions.

product
ratio
sum
difference

product

Which of the following thermocouples has the least temperature measurement range?

Copper-constantan
Chromel-alumel
Platinum-platinum/rhodium
Iron-constantan

Copper-constantan

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