IPC Flashcards
Which of the following is an undesirable dynamic characteristic of an instrument ?
Time lag
Load cells are used for the measurement of
Weight
Which of the following is the dynamic characteristics of an instrument ?
Fidelity
The __________ of a vapor pressure thermometer is a functioning element.
Pointer
A negative gain margin expressed in decibels means a/an __________ system.
Unstable
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
Typical specifications for design stipulates the gain margin and phase margin to be respectively
> 1.7 and > 30°
Working principle of radiation pyrometer is based on the
Stafan-Boltzman law
Dilute wine was used as a thermometric liquid initially to develop temperature scale. First emperical temperature scale developed was the __________ scale.
Fahrenheit
The operation of a rotameter is based on
variable flow area
The temperature of tempering oil baths maintained at 400°C during heat treatment of steel is measured by a/an __________ thermocouple.
iron-constantan
Which of the following temperature measuring instruments need not touch the object whose temperature is being measured ?
Radiation/infrared pyrometer
Thermal conductivity measurement com-prises the working principle of a
CO2analyser
Response of a system to a sinusoidal input is called __________ response.
Frequency
The closed loop pole of a stable second order system could be
both real and negative.
Smoke density of the flue gas going out of the chimney is measured by a
photo electric cell
The maximum service temperature for fibre glass used as thermocouple wire insulation material is __________ °C.
500
Zirconia probe is used for the continuous measurment of __________ flue gases going out of the furnace.
Oxygen in
Compositional analysis of __________ is done using mass spectrometer.
an isotope
Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature ?
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.
is undesirable in thermocouples used in industries,
Non-linear relation of emf to temperature
Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a
thermocouple
The __________ of a vapor pressure thermometer is a secondary element
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
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?
Peltier effect
In a shell and tube heat exchanger, the flow rate of heating/cooling fluid is the __________ variable.
manipulated
A non-linear chemical system is exemplified by a/an
non-isothermal CSTR
Radiation pyrometers as compared to thermocouples
can measure higher temperature.
Liquid flow rate in a small channel is best measured by a/an
pitot tube
Specific gravity of a liquid can not be measured by a/an
anemometer
temperature scale assigns 0° to the ‘ice point’ and 80° to the ‘steam point’.
Reumur
Dead zone is the
maximum change in the variable that does not change the reading of the instrument.
Humidity of air can be determined by a
sling psychrometer
Working principle of disappearing filament type optical pyrometer is based on the
Wien’s law
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
Range of hydrogen gas constant volume themometer is __________ °C.
0 to 100
The __________ of a vapor pressure thermometer is a primary element.
Bulb
A sinusoidal variation in the input passing through a linear first order system
gets attenuated (magnitude decreases).
Nitrogen gas constant volume thermometer is suitable for measuring a temperature of __________ °C.
> 100
Pick out the most suitable instrument for measuring temperature in the range of-40 to 425°C.
bimetallic thermometer
Accurate temperature measurement performance of a radiation pyrometer can not be affected, if the
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
Configuration of Bourdon spring tube is never made of __________ shape.
circular
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
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
underdamped response
Measurement of pressure in ammonia reactor is done by
Bourdon gauge
Flow rate of a river is measured by a/an
vane meter
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
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.
load
Paramagnetism method is not used for the composition determination of __________ in gases.
carbon dioxide
An amplitude ratio of 0.1 corresponds to __________ decibels.
-20
Pressure of 0.0001 absolute psi can be measured by __________ gauge.
Mcloid
thermometer can not measure sub-zero (< 0° C) temperature
Bimetallic
Starting temperature of optical radiation pyrometer is __________ °C.
800
Liquid argon level in a pressurised storage tank (at 3 kg/cm2 ) is measured by a/an
differential pressure gage
The deflection of the free end of the bimetallic strips in a bimetallic thermometer with temperature is nearly
linear
What is the ratio of output amplitude to input amplitude for a sinusoidal forcing function in a first order system ?
< 1
Reset rate is the another term used for __________ time.
integral
Continuous measurement of moisture in paper is done by
high resistance Wheatstone’s bridge circuit.
The amplitude ratio for the sinusoidal response of a __________ is 1.
transportation lag
The response of two tanks of same size and resistance in series is
critically damped
Measurement of sub-zero Celcius temperature in industry is done most commonly by
resistance thermometers
Liquid discharge from a tank or reservoir can not be measured by
orificemeters
Magnetic flowmeters are generally not used for the velocity/flow measurement of hydrocarbons due to their
low electrical conductivity
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
A constant volume gas thermometer employing __________ is used to measure sub-zero (i.e., < 0° C) temperature.
helium
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 ?
13
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 is not a differential pressure flow meter ?
Rotameter
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
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
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 Kcin response of first order system can be reduced by
introducing integral control.
In an exothermic chemical reactor, the manipulated variable is the flow rate of
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
Emf generated in a thermocouple depends on the temperature
difference between hot and cold junctions.
Radiation thermometer can not measure the temperature
of liquid oxygen
Temperature measurement by optical pyrometer is done above __________ point, which is 1063°C.
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
Mass spectrometer is used for the composition analysis of
isotopes
___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.
95
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
Small furnace draught is accurately measured by an inclined tube manometer, in which the manometric liquid used most commonly is
paraffin
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.
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
Working principle of radiation pyrometer is based on the
stefan-Boltzman law
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
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.
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.
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.
Close
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
In a shell and tube heat exchanger, the inlet temperature of heating/cooling fluid is the __________ variable.
load
Thermal wells used in temperature measurements should have
high transmissivity of radiation.
Which of the following flow-metering instru-ments is an areameter ?
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
Bourdon guage
Routh stability method uses __________ loop transfer function.
Closed
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.
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
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
36
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.
30
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/cm2
< 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
The level of a liquid under pressure can be determined using
differential pressure manometer
Which of the following is never used as an element of industrial resistance thermometer ?
Lead
A stable system is the one
for which the output response is bounded for all bounded input.
Meleoid gauge measures the __________ pressure
sub-atmospheric
Platinum resistance thermometer can be used upto antimony point which is __________ °C, and is the temperature of equilibrium between solid antimony & liquid antimony at normal atmospheric pressure.
961.93
630.74
Change of angle of refraction with composition comprises the working principle of a
refractrometer
Which of the following instruments is not used for measuring sub-zero (<0°) temperatures ?
Radiation pyrometer
Flame photometry is used for the determination of compositional analysis of
alkali metals
0n-off control which is a special case of proportional control, has a band width of about __________ percent.
0
The thermal emf-temperature relationship of most thermocouples is
parabolic
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/√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
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)
Working principle of mercury in glass thermometer is
volumetric expansion.
The frequency at which maximum amplitude ratio is attained is called the __________ frequency.
resonant
Minute depression of freezing point of a liquid solvent on addition of a solid solute can be best measured by a
Beckman thermometer
