(3) Process Control instrumentation Flashcards
Which of the following is an undesirable dynamic characteristic of an instrument ?
-Reproducibility
-Dead zone
-Time lag
-Static error
-Time lag
Which of the following is not the triple point of water ?
32°R
273°K
492°R
32°F
32°R
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).
Load cells are used for the measurement of
-stress
-weight
-strain
-velocity
weight
Which of the following is the dynamic characteristics of an instrument ?
-Reproducibility
-Sensitivity
-Dead zone
-Fidelity
Fidelity
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.
The __________ of a vapor pressure thermometer is a functioning element.
-pointer
-bourdon tube
-bulb
-none of these
pointer
A negative gain margin expressed in decibels means a/an __________ system.
-stable
-unstable
-critically damped
-none of these
unstable
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
Flapper nozzle is used in a/an __________ controller.
-electronic
-hydraulic
-pneumatic
-none of these
pneumatic
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°
Working principle of radiation pyrometer is based on the
-Wien’s law
-Kirchoffs law
-Stafan-Boltzman law
-Seebeck effect
Stafan-Boltzman law
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
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
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)
Which of the following is a desirable characteristic of an instrument ?
-High drift
-High fidelity
-High measuring lag
-Poor reproducibility
-High fidelity
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.
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
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)
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
Thermal conductivity measurement comprises the working principle of a
-CO2 analyser
-polarimeter
-spectrometer
-chromatograph
-CO2 analyser
Response of a system to a sinusoidal input is called __________ response.
-impluse
-unit step
-frequency
-none of these
frequency
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.
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
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)