PROCESS CONTROL & INSTRUMENTATION - INDIABIX Flashcards by Errynne Yanza

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

Time lag

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Which of the following is not the triple point of water ?

32°R

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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).

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

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Load cells are used for the measurement of

Weight

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

Fidelity

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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.

CO2 is the strongest paramagnetic gas.

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The __________ of a vapor pressure thermometer is a functioning element.

Pointer

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

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

solid semi-conductor

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Flapper nozzle is used in a/an __________ controller.

pneumatic

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Typical specifications for design stipulates the gain margin and phase margin to be respectively

> 1.7 and > 30°

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Working principle of radiation pyrometer is based on the

Stefan-Boltzman law

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Which of the following relates the emf. generated in a single homogeneous wire to the temperature difference ?

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.

Fahrenheit

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In a single tank system, the transfer function of level to inlet flow rate is

R/(TS + 1)

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Which of the following is a desirable characteristic of an instrument ?

High fidelity

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The operation of a rotameter is based on

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.

iron-constantan

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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)

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

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Thermal conductivity measurement comprises the working principle of a

CO2 analyser

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Response of a system to a sinusoidal input is called __________ response.

frequency

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The closed loop pole of a stable second order system could be

both real and negative

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Smoke density of the flue gas going out of the chimney is measured by a

photo electric cell

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Transfer function of transportation lag is

e^-TS

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Temperature measuring instruments are standardised mostly with __________ points of pure substances.

A. melting
B. boiling
C. both (a) & (b)
D. neither (a) nor (b)

both (a) & (b)

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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.

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.

500

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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

P-D controller

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Volumetric expansion is the working principle of the __________ thermometers

mercury in glass

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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)

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

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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).

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

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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)

both (a) and (b)

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Compositional analysis of __________ is done using mass spectrometer.

an isotope

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The function of a transducer is to

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

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Nichol’s chart deals with

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?

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

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__________ is undesirable in thermocouples used in industries,

Non-linear relation of emf to temperature

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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.

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

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For an input forcing function, X(t) = 2t^2, the Laplace transform of this function is

4/s^3

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Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a

thermocouple

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The __________ of a vapor pressure thermometer is a secondary element.

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

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?

Peltier effect

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

manipulated

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A non-linear chemical system is exemplified by a/an

non-isothermal CSTR

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The frequency response of a first order system, has a phase shift with lower and upper bounds given by

0, π/2

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Gas chromatography is used for the measurement of

concentration

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Which of the following thermocouples can measure the maximum temperature ?

Tungsten-molybdenum

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Radiation pyrometers as compared to thermocouples

can measure higher temperature.

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Liquid flow rate in a small channel is best measured by a/an

pitot tube

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Specific gravity of a liquid can not be measured by a/an

anemometer

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__________ temperature scale assigns 0° to the ‘ice point’ and 80° to the ‘steam point’.

Reumur

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Dead zone is the

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?

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

fidielity

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Thermistors are made of

metal oxides

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A barometer measures the __________ pressure.

absolute

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Humidity of air can be determined by a

sling psychrometer

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Thermocouple in a thermal well behaves as a true

multiple first order system.

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The transfer function for a P-D controller is

Kc(1+τD s)

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Bode diagram is a plot of

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

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Working principle of disappearing filament type optical pyrometer is based on the

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.

increase

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Pick out the wrong statement

A. Proportional controller is normally used for level control in industrial applications.
B. CSTR can be considered as a distributed parameter system.
C. Distributed parameter approach gives partial differential equation.
D. 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.

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

1/2

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The __________ of a vapor pressure thermometer is a primary element.

bulb

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The time constant of a first order process with resistance R and capacitance C is

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A sinusoidal variation in the input passing through a linear first order system

gets attenuated (magnitude decreases).

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Nitrogen gas constant volume thermometer is suitable for measuring a temperature of __________ °C.

> 100

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Pick out the most suitable instrument for measuring temperature in the range of-40 to 425°C.

A. mercury thermometer
B. bimetallic thermometer
C. radiation pyrometer
D. none of these

bimetallic thermometer

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

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

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Configuration of Bourdon spring tube is never made of __________ shape.

Circular

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Thermodynamic celcius scale of temperature measurement is

A. defined on the basis of melting point of ice and evaporation temperature of water vapor.
B. defined on the basis of melting point of ice and condensation temperature of water vapor.
C. having an interval of 100° between ice point to steam point.
D. 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°

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

underdamped response.

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Resistance of a gas in a vessel is given by (where, P = pressure, V = volume of the vessel, n = no. of moles of the gas, R = gas constant)

V/nRT

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Measurement of pressure in ammonia reactor is done by

Bourdon gauge

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The fluid used in hydraulic controller is
water

oil

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Flow rate of a river is measured by a/an

vane meter

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Which of the following thermocouple materials does not contain nickel?

A. Alumel
B. Chromel
C. Constantan
D. 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

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Identify an unbounded input from inputs whose transfer functions are given below

1/S^2

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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

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Feed forward controller accounts for the __________ changes.

load

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Which thermocouple can be used to measure a temperature of around 1400°C ?

A. Copper-constantan
B. Aluminium-chromel
C. Platinum-platinum+rhodium
D. 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 ?

Alcohol in glass thermometer

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Concentration of sugar solution can be determined by the

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

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Which of the following can not measure a temperature of 1600°C ?

Platinum resistance thermometer

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The temperature range for which copper resistance thermometer can be used is __________ °C

-200 to 150

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

carbon dioxide

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An amplitude ratio of 0.1 corresponds to __________ decibels.

-20

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For increased speed of response of an expansion pressure spring thermometer, the thermometer bulb should have a

A. large area but small mass.
B. high thermal conductivity.
C. small specific heat.
D. all’a’, ‘b’ & ‘c’.

all’a’, ‘b’ & ‘c’.

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

Mcloid

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Pirani gauge is used for the measurement of

high vacuum

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The __________ of the fluid contained in the temperature sensing element (i.e., bulb) of filled system thermometers changes with change in temperature.

A. pressure
B. volume
C. viscosity
D. all (a), (b) and (c)

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

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The characteristic equation for the control system with a closed loop transfer function G1/1 + G2 is given by 1 + G2 = 0. The characteristic equation for the control system

A. depends only upon the open loop transfer function.
B. determines its stability.
C. is the same for set point or load changes.
D. all ‘a’, ‘b’ & ‘c’

all ‘a’, ‘b’ & ‘c’

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

Bimetallic

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Starting temperature of optical radiation pyrometer is __________ °C

800

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Liquid argon level in a pressurised storage tank (at 3 kg/cm^2 ) is measured by a/an

differential pressure gage

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Which of the systems having following transfer functions is stable?

1/(s^2 + 2s + 2)

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

2 AT

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

linear

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Alphatron measures pressure __________ microns.
< 1

> 3

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

< 1

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

heat flow rate

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Reset rate is the another term used for __________ time.

integral

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Continuous measurement of moisture in paper is done by

high resistance Wheatstone’s bridge circuit.

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Psychrometer determines the

humidity of gases

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A mercury barometer measures the __________ pressure.

atmospheric

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Positioning controllers are used for

high loads

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The amplitude ratio for the sinusoidal response of a __________ is 1.

transportation lag

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

critically damped

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The amplitude ratio for the sinusoidal response of __________ is < 1.

first order system

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Which of the following is a ‘contact’ pyrometer ?

resistance pyrometer

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Which of the following is not a speed measuring instrument?

Psychrometer

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

resistance thermometers

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Use of I-control along with P-control facilitates

elimination of offset

Turbine flow meters are suitable for

both (b) and (c)

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

orificemeters

Which of the following is not a mechanical pressure sensing element?

U-tube

__________ are analysed using a polarograph.

Solids

Which of the following judges the accuracy of an instrument?

Static error

On-off controllers are normally used for

Low loads

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

low electrical conductivity

Which of the following controllers has maximum offset ?

A. P-controller
B. P-I controller
C. P-D controller
D. P-I-D controller

P-controller

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

Mcloid

High temperature of around 2000°C of incandescent gas mantles is measured by a/an

radiation pyrometer

The unit step response of the transfer function 1/(s^2 + 2s + 3)

has a damped oscillatory characteristics

The time constant of a unity gain, first order plus time delay process is 5 min. If the phase lag at a frequency of 0.2 rad/min is 60°, then the dead time (in minutes) is

5π/12

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

A. Ice (F.P) and steam (B.P)
B. Oxygen and sulphur (B.P)
C. Antimony and silver (F.P)
D. 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

pH meter has

two cells

Routh test

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

slower and non-oscillatory

What is the normal percentage of rhodium in platinum + rhodium element used in the thermocouple?

Helium gas constant volume thermometer is suitable for the measurement of a temperature of __________ °C.

< 0

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

Sinusoidal

Which of the following thermocouples is the most suitable for measuring a temperature of about 1600°C in an oxidizing atmosphere?

Platinum-platinum + rhodium

Mercury thermometer can be used to measure the temperature up to __________ °C.

350

Vapour actuated pressure spring thermometer does not require ambient temperature compensation. Ambient temperature compensation is provided in gas or liquid expansion pressure spring thermometer by

A. making the volume of thermometer bulb as large as conveniently possible.
B. reducing the volume of the capillary to a minimum.
C. reducing the volume of the receiving element to a minimum.
D. all ‘a’, ‘b’ & ‘c’

all ‘a’, ‘b’ & ‘c’

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

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 ?

Mercury

Bourdon gauges are used for measuring pressure (kg/cm^2 )

> 2 (gauge)

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

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

spring loaded diaphragm valve

An aneroid barometer measures the __________ pressure.

absolute

A bolometer is

A. used for the measurement of thermal radiation.
B. an element which senses optical input and delivers thermal output.
C. both (a) & (b).
D. neither (a) nor (b).

both (a) & (b)

Thermal wells are used in the temperature measurement to

guard against corrosive and oxidising action on thermocouple materials

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

introducing integral control.

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

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

In a second order under damped system, the

overshoot (which is a measure of how much the response exceeds the ultimate value) increase with the decrease of damping co-efficient e

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

coolant

Very low pressure is expressed in microns(μ), which is equal to __________ mm of Hg coloumn (absolute) at 0°C.

0.001

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

Emf generated in a thermocouple depends on the temperature

difference between hot and cold junctions

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

volumetric expansion

Radiation thermometer can not measure the temperature

of liquid oxygen.

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

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

Dilatometer is used to measure

contraction/expansion due to changes in temperature

Mass spectrometer is used for the composition analysis of

isotopes

A first order system with a time constant of 1 min is subjected to frequency response analysis. At an input frequency of 1 radian/min, the phase shift is

-45°

__________ stability method uses open loop transfer function.

Nyquist

A pyranometer is an instrument used for measuring the

global radiation

All the thermocouples used for temperature measurement use dissimilar metal

wires

Composition of alloys can be determined by

polarograph

Optical activity of a solution can be determined using a

polarimeter

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

frequency response methods

Stabilising time for the controllers is the time required for the response to reach __________ percent of its ultimate value.

Time constant is the

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

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

second

Emf developed by a thermocouple while measuring a temperature of 400°C is 22 mV. The type of thermocouple used is

iron-constantan

Bode stability method uses __________ loop transfer function

open

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?

Brass

Which of the following is not a second order instrument ?

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

paraffin

Specific conductance is defined as the reciprocal of resistance in ohms of 1c.c. of liquid at a specified temperature. Its value for distilled water is about __________ micro mho/cm^3.

A simple pitot tube measures the

static pressure

For a feed back control system to be stable, the

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

A mercury thermometer can not be used to measure the temperature below the freezing point of mercury, which is __________ °C.

-38.9

__________ controller has the maximum stabilising time.

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

optical pyrometer

Stalagmometer is used for the measurement of

surface tension

The deflection in diaphragm (which is used as pressure sensor in pneumatic and electronic instruments) is dependent on the metal thickness, its diameter (d) and shape & number of corrugations. Its deflection is proportional to

d^4

Working principle of radiation pyrometer is based on the

Stefan-Boltzman law

Liquid levels in autocalves are measued by

differential float type manometer

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

millivolts

A pyrheliometer is an instrument used for measuring the

beam radiation

Flow rate through an orifice is __________ the pressure differential.

proportional to the square root of

Thermistors are used in __________ devices.

A. voltage measuring
B. temperature measuring
C. temperature compensating
D. both(b)&(c)

both (b) & (c)

__________ is the static characteristics of an instrument,

Drift

Phase lag of the frequency response of a second order system to a sinusoidal forcing function

approaches 180° asymptotically

Dead zone in an instrument must be less than __________ percent of the scale.

0.2

Emission spectroscopy is used for

solids and metal analysis.

Gas analysis is commonly done using the

thermal conductivity cell

Thermal conductivity measurement is used for the determination of

CO2 percentage in the flue gas.

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

dielectric constant end loss factor

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

carbon dioxide

Zirconia probe is used for the measurement of

% O2 in flue gas.

The root locus method, a pole of a transfer function G(s) is the value of s for which G(s) approaches

∞

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

Bourdon tube

Suppose that the gain, time constant and dead time of a process with the following transfer function: Gc(s) = 10 exp( - 0.1s)/(0.5s + 1) are known with a possible error of ± 20% of their values. The largest permissible gain Kc of a proportional controller needs to be calculated below taking the values of process gain, time constant and dead time as

12, 0.6, 0.12

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

the maximum

Characteristic equation is the denominator of __________ loop transfer function.

closed

Operating range of a temperature measuring instrument is 800 to 1600°C. It could be a/an __________ pyrometer.

photoelectric

Polarograph is meant for the analysis of

solids

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

Weir

Flow rate of sludge is not measured by a/an

A. orificemeter
B. open weir
C. kennison nozzle
D. both (b) & (c)

both (b) & (c)

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

load

A bimetallic thermometer as compared to industrial mercury in glass thermometer has almost the same

A. temperature measuring range (- 40°C to 450°C).
B. accuracy (± 1% of span).
C. speed of response.
D. all a, b & c.

all a, b & c.

Thermal wells used in temperature measurements should have

high transmissivity of radiation.

Which of the following flow-metering instruments is an area meter ?

rotameter

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

ceramic fibre

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

Ionisation gauge

Routh stability method uses __________ loop transfer function.

closed

Pyrometry refers to the measurement of temperature

which is of higher magnitude.

Photoelectric pyrometers are suitable in the temperature range of __________ °C.

800 - 1600

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

synthetic rubber

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

servo problem

Hot wire anemometer is used for the measurement of

flow rates of fluids.

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

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

air to open valve with the controller indirect acting

Bourdon tube is never made of

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

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

level of liquid

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

controlled

Mcleoid gauge is used to measure the

vacuum

What is the Laplace transform of impulse input having magnitude ‘X’ ?

Thermocouple is suitable for measuring

both high and low temperatures

Bimetal strips are not used in

thermocouples

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

critically damped

Nickel percentage in invar which is an iron-nickel alloy, and is used as a thermocouple material is

Silver point temperature is __________ °C.

960.5

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

more than one

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

Magnetic flow meter

With increase in temperature, the electrical conductivity of the platinum used in the resistance thermometer

decreases

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

helium

__________ is an example of distributed parameter system

tubular reactor

Which of the following is not classified as a thermo electric pyrometer ?

Optical pyrometer (disappearing filament type)

Maximum differential pressure in liquid manometer is __________ psi.

Phase margin is equal to

180° - phase lag

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

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

thermal conductivity cell

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

semi conductors

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

strip

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

orifice meter

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

time

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

Alcohol in glass thermometer

Liquid column manometers are used for measuring the pressure __________ kgf/cm^2 .

< 3 (gage)

Cascade control means

more than one feed-back loop

The level of a liquid under pressure can be determined using

differential pressure manometer

Temperature measurement range of iron-constantan thermocouple is 0 to 870°C. It can be used to measure sub zero temperature, because at lower temperature

A. emf produced is very low of the order of microvolt.
B. embrittlement of iron occurs.
C. rusting of iron takes place.
D. both (b) and (c).

both (b) and (c)

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

lead

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

Mercury thermometer

A stable system is the one

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

The Laplace transform of exp(at), where a > 0, is defined only for the Laplace parameter, s > a since

the Laplace transform of integral of exp(at) has finite values only for s > a.

Meleoid gauge measures the __________ pressure.

sub-atmospheric

Which of the following thermocouples is capable of measuring a temperature of -50°C?

Platinum - platinum + rhodium

Platinum resistance thermometer can be used up to antimony point which is __________ °C, and is the temperature of equilibrium between solid antimony & liquid antimony at normal atmospheric pressure.

630.74

Which of the following instruments is not used for measuring sub-zero (<0°) temperatures ?

Radiation pyrometer

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

refractrometer

Which of the following is not suitable for measuring the temperature of a red hot object in the range of 800 - 1600°C?

Thermocouples

Flame photometry is used for the determination of compositional analysis of

alkali metals

Reference points i.e., ice point and steam point in Reaumer temperature scale are respectively

0° & 80°

Which of the following is not a composition measuring instrument ?

A. Thermal conductivity cell
B. Mass spectrometer
C. Polarograph
D. Hot wire anemometer

Hot wire anemometer

Emf developed by a thermocouple while measuring a temperature of 800°C is about 31 mV. The type of thermocouple used is

chromel-alumel

Which of the following thermocouples is incapable of measuring sub-zero (i.e., < 0°C) temperature?

Platinum-platinum + rhodium

Platinum resistance thermometer is the international standard for temperature measurement between

A. triple point of hydrogen and freezing point of antimony
B. 13.81°K to 903.9°K
C. both (a) and (b)
D. neither (a) nor (b)

both (a) and (b)

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

The thermal emf-temperature relationship of most thermocouples is

parabolic

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

log-lag

Which is the strongest paramagnetic gas?

Continuous measurement of specific gravity of a liquid is done by

A. hydrometer
B. contact-type electric indicators
C. displacement meter
D. both (a) and (c)

both (a) and (c)

A first order system with unity gain and time constant τ is subjected to a sinusoidal input of frequency w = 1/τ. The amplitude ratio for this system is

1/sqrt(2)

For measuring the temperature of a red hot furnace, which is the most suitable instrument ?

Optical pyrometer

Stroboscope is used for the measurement of

rpm of a flywheel

In second order underdamped system,

decay ratio = (overshoot)^2

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

platinum-platinum/rhodium thermocouple

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

90°

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

electrical resistance through the paper

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

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.

Transfer lag decreases as the number of stages decreases.

Working principle of mercury in glass thermometer is

volumetric expansion

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

resonant

Which of the following can measure temperatures in the range of - 20 to 300°C ?

A. Mercury in glass thermometer
B. Vapor pressure thermometer
C. Resistance thermometer
D. None of these.

None of these.

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

proportional integral-derivative (PID) controller

Conversion formula for converting amplitude ratio (AR) into decibels is

Decibel = 20 log10 (AR)

Normal mercury thermometer can be used to measure a temperature of about 300°C. However, its maximum temperature measurement range can be increased up to about 500°C by

filling nitrogen under pressure in the stem

A manometer measures the __________ pressure.

gauge

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

Beckman thermometer

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

hot blast (air) from stoves

Gain margin is equal to the

reciprocal of amplitude ratio

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

log-log

Temperature of molten pig iron (1450°C) and molten slag (1500°C) flowing out of a blast furnace is measured by a/an

A. chromel-alumel thermocouple
B. optical pyrometer
C. radiation pyrometer
D. either (b) or (c)

either (b) or (c)

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

product

Mercury thermometer is commonly used for low temperature measurement. The freezing point and boiling point of mercury are respectively __________ °C.

-39 and 350

Ordinary mercury in glass thermometer is used for measuring temperature up to 120°C. However, for measuring higher temperature up to __________ °C, thermometer is made by filling nitrogen under pressure above the mercury, which stops the evaporation of mercury and reduces the chance of broken thread of mercury.

550

Composition of natural gas is determined by the

A. Haldane apparatus
B. mass spectrometer
C. chromatograph
D. both (b) and (c)

both (b) and (c)

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

Copper-constantan

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