(3) Process Control instrumentation Flashcards by Deleted Deleted

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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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).

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

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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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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 analyser
-polarimeter
-spectrometer
-chromatograph

-CO2 analyser

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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 a. eTS b. e-TS c. 1/TS+1 d. none of these

b. e-TS

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

both (a) & (b)

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.

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

500

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

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

-mercury in glass

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).

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)

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

The transfer function for a PID controller is (where, τ i is the integral (reset) time and τD is the derivative time.) Kc(1 + τis + τD ). s

τD * s (last)

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)

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

an isotope

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.

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.

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.

The symbol for "capillary line" in instrumentation diagram is -.-.-.-.-- --x---x---x --//---//--// ---------------

---x---x----x

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.

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.

The transfer function for an ideal proportional plus reset controller (reset time T) is

Kc(1 + 1/TS)

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

__________ 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

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

0, π/2

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

4/s3

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

Bourdon tube

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

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

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

-non-isothermal CSTR

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

manipulated

The second order system with the transfer function 4/s2+2s+4 has a damping ratio of 2.0 0.5 1.0 4.0

0.5

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

-pitot tube

__________ temperature scale assigns 0° to the 'ice point' and 80° to the 'steam point'. -Celcius -Rankine -Reumur -Farenhite

Reumur

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

concentration

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

-Tungsten-molybdenum

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.

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

-anemometer

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.

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

-Mercury in glass thermometer

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

fidielity

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

-metal oxides

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

-absolute

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

-sling psychrometer

(3) Process Control instrumentation Flashcards

(65 cards)