PCI 1,2 Flashcards by Carl Soriano

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

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.
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.

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 com-prises 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 eTS e-TS none of these

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

. 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)

. 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)

. 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)

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).

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

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

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.

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.

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.

__________ 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

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.

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

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

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 Key: abpel

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

manipulated

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

non-isothermal CSTR

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

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.

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

pitot tube

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

anemometer

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

Reumur

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

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.

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

Kc(1+τD s)

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

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

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 Key: filament

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

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.

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

0 to 100

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

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

bulb

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

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).

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

> 100.

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

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.

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

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

circular

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)

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

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.

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

Bourdon gauge

The fluid used in hydraulic controller is water steam air oil

oil

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

vane meter

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

None of these.

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

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

1/S2

"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

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

load

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

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

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

polarimetry

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

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

Platinum resistance thermometer