IBX - Process Cont. & Instru. Sec. 1 to 7 Flashcards
Indiabix - Process Control & Instrumentation Sec. 1 to 7
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 com-prises 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
e^(TS)
e^(-TS)
1/(TS+1)
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)
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)
The transfer function for a PID controller is (where, τi is the integral (reset) time and τD is the derivative time.)
Kc (1 + τi⋅s + τD )⋅s
Kc (1 + τi⋅s + 1/τD⋅s)
Kc [1 + τi⋅s + 1/(τD⋅s)]
Kc [1 + 1/(τi⋅s) + 1/(τD⋅s)]
Kc (1 + τi⋅s + 1/τD⋅s)
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.
The symbol for “capillary line” in instrumentation diagram is
......_
–x–x–x–x–
–//–//–//–
___________
–x–x–x–x–
__________ 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) = 2t^2, the Laplace transform of this function is
2/s^2
4/s^2
2/s^3
4/s^3
4/s^3
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
The second order system with the transfer function [4/(s^2 + 2s +4)] has a damping ratio of
2.0
0.5
1.0
4.0
0.5
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 transfer function for an ideal proportional plus reset controller (reset time T) is
Kc (1 +1/TS)
Kc (1 + TS)
Kc (1 + TS)
Kc/(1 + S/T)
Kc (1 +1/TS)
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.
Liquid 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
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
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.
What is the overall transfer function (C/R) of the following block diagram if G = G1⋅G2⋅G3 and H =H1⋅H2.
1/(1+GH)
G/(1+GH)
H/(1+GH)
G/(1-GH)
G/(1+GH)
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.
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
nRT/V
nRT/V
P/nRT
V/nRT
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/S^2
1/(S^2 + 1)
1/S^2
“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
Nyquist
Routh stability
none of these
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
Which of the following can not measure a temperature of 1600°C ?
Platinum resistance thermometer
Thermocouple
Photo-electric pyrometer
Radiation pyrometer
Platinum resistance thermometer
The temperature range for which copper resistance thermometer can be used is __________ °C.
0 to 150
-200 to 150
350 to 750
500 to 900
-200 to 150
Paramagnetism method is not used for the composition determination of __________ in gases.
oxygen
oxides of nitrogen
carbon dioxide
any of these
carbon dioxide
An amplitude ratio of 0.1 corresponds to __________ decibels.
20
-20
10
-10
-20
For increased speed of response of an expansion pressure spring thermometer, the thermometer bulb should have a
large area but small mass.
high thermal conductivity.
small specific heat.
all’a’, ‘b’ & ‘c’.
all’a’, ‘b’ & ‘c’.
Pressure of 0.0001 absolute psi can be measured by __________ gauge.
Mcloid
Pirani
thermocouple
none of these
Mcloid
Pirani gauge is used for the measurement of
very high pressure.
high vacuum.
liquid level under pressure.
liquid level at atmospheric pressure
high vacuum.
The __________ of the fluid contained in the temperature sensing element (i.e., bulb) of filled system thermometers changes with change in temperature.
pressure
volume
viscosity
all (a), (b) and (c)
all (a), (b) and (c)
Transfer functions X/Y for which of the following block diagrams is (G1+ G1⋅G2⋅G3)/(1+G2⋅G3)
A
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
depends only upon the open loop transfer function.
determines its stability.
is the same for set point or load changes.
all ‘a’, ‘b’ & ‘c’
all ‘a’, ‘b’ & ‘c’
__________ thermometer can not measure sub-zero (< 0° C) temperature,
Mercury in glass
Bimetallic
Vapor pressure
Resistance
Bimetallic
Starting temperature of optical radiation pyrometer is __________ °C.
800
400
1200
1500
800
Liquid argon level in a pressurised storage tank (at 3 kg/cm2 ) is measured by a/an
gage glass
external float gage
differential pressure gage
none of these
differential pressure gage
Which of the systems having following transfer functions is stable?
1/(s2+ 2)
1/(s2-2s + 3)
1/(s2 + 2s + 2)
exp(-20s)/(s2 + 2s-l)
1/(s2 + 2s + 2)
What is the dynamic error in a critically damped second order instrument for a ramp input (At) ?
0.5 AT
2 AT
sqrt(AT)
1.5 AT
2 AT
The transfer function for a first order process with time delay is
[e^(-Td⋅S)]/(T⋅S+1)
An ideal PID controller has the transfer function [1 + 1/0.55 + 0.25]. The frequency at which the magnitude ratio of the controller is 1, is
0.5/0.2
0.2/0.5
0.2 x 0.5
1/sqrt(0.2 x 0.5)
1/sqrt(0.2 x 0.5)
The deflection of the free end of the bimetallic strips in a bimetallic thermometer with temperature is nearly
linear
non-linear
parabolic
hyperbolic
linear
Alphatron measures pressure __________ microns.
< 1
< 3
> 3
< 0.1
> 3
What is the ratio of output amplitude to input amplitude for a sinusoidal forcing function in a first order system?
1
>1
< 1
none of these
< 1
The unit step response of the transfer function (2s - 1)/[(3s + 1)(4s + 1)] reaches its final steady state assymptotically after
a monotonic increase.
a monotonic decrease.
initially increasing and then decreasing.
increasing decreasing and then increasing.
a monotonic increase.
A process is initially at steady state with its output y=l for an input u=l. The input is suddenly changed to 2 at time t=0. The output response is y(t)=1+2t. The transfer function of the process is
2/s
1 + 2/s^2
1 + 2/s
(1/s)(1+2/s)
(1/s)(1+2/s)
The term analogous to the electrical current in a thermal system is the
temperature difference
heat flow rate
heat content in the system
none of these
heat flow rate
Reset rate is the another term used for __________ time.
dead
integral
derivative
none of these
integral
Continuous measurement of moisture in paper is done by
sling psychrometer.
hair-hygrometer.
weighing.
high resistance Wheatstone’s bridge circuit.
high resistance Wheatstone’s bridge circuit.
Psychrometer determines the
humidity of gases
moisture content of solids
water of crystallisation
hygroscopic nature of solids
humidity of gases
Which of the systems having the following transfer function is stable ?
1/(S^2 + 2)
1/(S^2 - 2S + 3)
1/(S^2 + 2S + 2)
exp(-20S)/(S^2 + 2S - 1)
1/(S^2 + 2S + 2)
The calibration data of a thermocouple with its cold junction at 0°C are given below.
Hot Temp (°C) | 0 | 20 | 40 | 60 | 80 |100 |
Thermo ermf (mv) |0.00|0.80|1.61|2.43|3.26|4.10|
The hot junction of the thermocouple is placed in a bath at 80°C, while its cold junction is at 20°C. What is the emf of thermocouple?
3.26 mv
0.80 mv
2.46 mv
2.43 mv
2.43
A mercury barometer measures the __________ pressure.
atmospheric
gauge
vacuum
absolute
atmospheric
Positioning controllers are used for
low loads
temperature changes
high loads
flow rate changes
high loads
The amplitude ratio for the sinusoidal response of a __________ is 1.
first order system
second order system
transportation lag
none of these
transportation lag
The response of two tanks of same size and resistance in series is
under damped
critically damped
over damped
none of the above
critically damped
The frequency response of a dynamic element shows a constant magnitude ratio at all frequencies. The element exhibits a negative phase shift at all frequencies. The absolute value of the phase shift increases linearly with frequency. The element has the transfer function
e^(-τs)
The amplitude ratio for the sinusoidal response of __________ is < 1.
transportation lag
first order system
second order system
none of these
first order system
Which of the following is a ‘contact’ pyrometer?
resistance pyrometer
optical pyrometer
radiation pyrometer
infra red pyrometer
resistance pyrometer
Which of the following is not a speed measuring instrument?
Psychrometer
Stroboscope
Tachometer
All (a), (b) and (c)
Psychrometer
Measurement of sub-zero Celcius temperature in industry is done most commonly by
thermocouples
resistance thermometers
gas thermometers
bi-metallic thermometers
resistance thermometers
For the block diagram shown below :
[question no. 37 in IBX]
The characteristic equation is
τl S (τps + 1) + Kc . Kp (τlS + 1) e-τd s = 0
(τmS + 1) (τpS + 1) + Km . Kp e-τd S = 0
τl S(τm S + 1) (τp S + 1) +Kc . Kp . Km (τl s + 1) e-τdS = 0
(τms + 1) (τp s + 1) + Kc . Kp . Km . e-τdS = 0
τl S(τm S + 1) (τp S + 1) +Kc . Kp . Km (τl s + 1) e-τdS = 0
Use of I-control along with P-control facilitates
elimination of offset
reduction of offset
reduction of stability time
none of these
elimination of offset
Turbine flow meters are suitable for
very limited flow ranges.
cryogenic flow measurements.
aerospace and in air borne applications.
both (b) and (c).
both (b) and (c).
Liquid discharge from a tank or reservoir can not be measured by
orifice meters
weirs
mouthpieces
notches
orifice meters
Which of the following is not a mechanical pressure sensing element?
Bellows
Diaphragm
Bourdon tube
U-tube
U-tube
__________ are analysed using a polarograph.
Isotonic solutions
Solids
Liquids
Gases
Solids
Which of the following judges the accuracy of an instrument?
Dead zone
Drift
Static error
None of these
Static error
On-off controllers are normally used for
low loads
temperature changes
flow rate changes
none of these
low loads
Magnetic flowmeters are generally not used for the velocity/flow measurement of hydrocarbons due to their
low thermal conductivity.
low electrical conductivity.
high viscosity index.
low flash point.
low electrical conductivity.
Which of the following controllers has maximum offset?
P-controller
P-I controller
P-D controller
P-I-D controller
P-controller
Pressure of 0.01 psi (absolute) can be measured by __________ gauge.
ionisation
Pirani
Mcloid
none of these
Mcloid
High temperature of around 2000°C of incandescent gas mantles is measured by a/an
specially designed thermocouple.
optical pyrometer.
radiation pyrometer.
none of these.
radiation pyrometer.
The unit step response of the transfer function 1/(s2 + 2s + 3)
has a non-zero slope at the origin.
has a damped oscillatory characteristics.
is overdamped
is unstable
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
π/6
π/12
π/3
5π/12
Which of the following does not figure in the list of seven substances selected for international temperature scale?
Ice (F.P) and steam (B.P)
Oxygen and sulphur (B.P)
Antimony and silver (F.P)
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
hydrogen
nitrogen
none of these
helium
pH meter has
one cell
two cells
three cells
no cell
two cells
Routh test
criterion provides information about the actual location of roots.
cannot be used to test the stability of a control system containing transportation lag.
criterion is not applicable to systems with polynomial characteristic equation.
can not determine as to how many roots of the characteristics equation have positive real roots.
cannot be used to test the stability of a control system containing transportation lag.
The open loop transfer function of a process is K⋅[(s + 1)(s + 4)/(s + 2)(s +3)]. In the root locus diagram, the poles will be at
-1, -4
1, 4
-2, -3
2, 3
-2, -3
When a bare thermocouple is covered by a protective sheath, the response becomes
faster and oscillatory.
faster and non-oscillatory.
slower and oscillatory.
slower and non-oscillatory.
slower and non-oscillatory.
What is the normal percentage of rhodium in platinum + rhodium element used in the thermocouple?
0.1
3
13
29
13
Helium gas constant volume thermometer is suitable for the measurement of a temperature of __________ °C.
< 100
< 0
> 0
> 800
< 0
Bode diagram are generated from output response of the system subjected to which of the following input?
Impulse
Step
Ramp
Sinusoidal
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
Iron-constantan
Copper-constantan
Chromel-alumel
Platinum-platinum + rhodium
Mercury thermometer can be used to measure the temperature up to __________ °C.
100
250
350
750
350
The transfer function of a process is 1/(16s^2 + 8s + 4). If a step change is introduced into the system, then the response will be
under damped
critically damped
over damped
none of these
under damped
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
making the volume of thermometer bulb as large as conveniently possible.
reducing the volume of the capillary to a minimum.
reducing the volume of the receiving element to a minimum.
all ‘a’, ‘b’ & ‘c’.
all ‘a’, ‘b’ & ‘c’.
Which of the following is not a differential pressure flow meter?
Rotameter
Flow nozzle
Orificemeter
Venturimeter
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?
Water
Mercury
Methyl alcohal
Carbon-tetrachloride
Mercury
Bourdon gauges are used for measuring pressure (kg/cm2 )
< atmospheric
> 2 (gauge)
< 2 (gauge)
> 10 (absolute)
> 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
current
flux density
voltage
light intensity
A typical example of a physical system with under damped characteristic is a
U-tube manometer.
spring loaded diaphragm valve.
CSTR with first order reaction.
thermocouple kept immersed in a liquid filled thermowell.
spring loaded diaphragm valve.
An aneroid barometer measures the __________ pressure.
atmospheric
absolute
vacuum
gage
absolute
A bolometer is
used for the measurement of thermal radiation.
an element which senses optical input and delivers thermal output.
both (a) & (b).
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
reduce measuring lag.
increase the fidelity.
increase the sensitivity.
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
reducing value of Kc.
introducing integral control.
introducing derivative control.
none of the above.
introducing integral control.
A system with a double pole at the origin is unstable since the corresponding term in the time domain
is a constant.
grows exponentially with time.
grows linearly with time.
decays linearly with time.
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
a metal powder or graphite
oil
mercury
air
In a second order under damped system, the
time required for the response of first reach its ultimate value is called the response time.
overshoot (which is a measure of how much the response exceeds the ultimate value) increase with the decrease of damping co-efficient e.
decay ratio (which is the ratio of the sizes of successive peaks) is equal to the reciprocal of overshoot.
characteristics of a step response is represented by
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
reactants
product
none of these
coolant
Very low pressure is expressed in microns(μ), which is equal to __________ mm of Hg coloumn (absolute) at 0°C.
0.0001
0.001
0.01
0.1
0.001
The inverse Laplace transform of the function
f(s) = 1/S(1+S) is
1 + e^t
1 - e^t
1 + e^-t
1 - e^-t
1 - e^-t
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
N2
O2
CO
CO2
Emf generated in a thermocouple depends on the temperature
of cold junction only.
of hot junction only.
difference between hot and cold junctions.
difference between cold junction and atmospheric temperature.
difference between hot and cold junctions.
Working principle of mercury in glass thermometer is based on the __________ of mercury with increase in temperature.
increase of pressure
increase of thermal conductivity
volumetric expansion
differential linear expansion
volumetric expansion
Number of poles in a system with transfer function
1/(s^2 + 2s^2 +1) is
2
5
3
1
3
Radiation thermometer can not measure the temperature
inside a pressure vessel.
of an object without coming in contact with it.
of liquid oxygen.
of moving objects at high temperature.
of liquid oxygen.
Temperature measurement by optical pyrometer is done above __________ point, which is 1063°C.
antimony
gold
silver
nickel
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
O2
NO
NO2
CO2
Dilatometer is used to measure
stress
strain
deflection
contraction/expansion due to changes in temperature
contraction/expansion due to changes in temperature
Mass spectrometer is used for the composition analysis of
alloys
solids
isotopes
none of these
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°
-90°
-180°
-45°
-45°
__________ stability method uses open loop transfer function.
Nyquist
Mikhalov
Ruth
none of these
Nyquist
A pyranometer is an instrument used for measuring the
beam radiation.
global radiation.
bright sunshine period.
none of these.
global radiation.
All the thermocouples used for temperature measurement use dissimilar metal
strips
bars
wires
beads
wires
The transfer function of a first order system is
1/(Ts+1)
1/Ts
s/(Ts+1)
none of these
1/(Ts+1)
Optical activity of a solution can be determined using a
polarimeter
polarograph
dilatometer
refractrometer
polarimeter
Stability of a control system containing a transportation lag can be best analysed by
Routh test
root locus methods
frequency response methods
none of these
frequency response methods
Stabilising time for the controllers is the time required for the response to reach __________ percent of its ultimate value.
63.2
87.5
95
100
95
Time constant is the
time taken by the controlled variable to reach 63.2% of its full change.
same as transportation lag.
same as dead time.
time required by the measured variable to reach 63.2% of its ultimate change.
time taken by the controlled variable to reach 63.2% of its full change.
Mercury manometer (U-tube type) exemplifies a __________ order system.
zero
first
second
third
second
Emf developed by a thermocouple while measuring a temperature of 400°C is 22 mV. The type of thermocouple used is
chromel-alumel
iron-constantan
platinum-rhodium
platinum-platinum+rhyodium
iron-constantan
Bode stability method uses __________ loop transfer function.
open
closed
either (a) or (b)
neither (a) nor (b)
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?
Nickel
Brass
Chromel
Invar
Brass
Which of the following is not a second order instrument?
Mercury in glass thermometer with covering.
Bare mercury in glass thermometer.
Pressure gauge with one bellow, two tubes and a tank.
None of these.
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
water
carbon tetrachloride
paraffin
ethylene glycol
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/cm3.
50
100
10
1
1
A simple pitot tube measures the
average velocity
maximum velocity
point velocity
static pressure
static pressure
For a feed back control system to be stable, the
roots of the characteristic equation should be real.
poles of the closed loop transfer function should lie in the left half of the complex plane.
Bode plots of the corresponding open loop transfer function should monotoni-cally decrease.
poles of the closed loop transfer function should lie in the right half of the complex plane.
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
-11.9
-60.9
-80.9
-38.9
__________ controller has the maximum stabilising time.
P
PD
PI
PID
PI
Out of the following temperature measuring instruments, the measurement accuracy will be minimum for the
mercury in glass thermometer.
optical pyrometer.
iron-constantan thermocouple.
alcohol filled thermometer.
optical pyrometer.
Stalagmometer is used for the measurement of
kinematic viscosity
surface tension
refractive index
optical activity
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
d^2
d^3
d^4
d^4
Working principle of radiation pyrometer is based on the
Wien’s law
Kirchoffs law
stefan-Boltzman law
Seebeck effect
stefan-Boltzman law
Liquid levels in autocalves are measured by
simple float
differential float type manometer
glass gauge
none of these
differential float type manometer
E.m.f. generated by thermocouples is of the order of
millivolts
microvolts
volts
kilo volts
millivolts
A pyrheliometer is an instrument used for measuring the
bright sunshine period.
beam radiation.
diffuse radiation.
none of these.
beam radiation.
Flow rate through an orifice is __________ the pressure differential.
proportional to
inversely proportional to the square root of
proportional to the square root of
inversely proportional to the square of
proportional to the square root of
Thermistors are used in __________ devices.
voltage measuring
temperature measuring
temperature compensating
both(b)&(c)
both(b)&(c)
__________ is the static characteristics of an instrument,
Response
Tine lag
Drift
dynamic error
Drift
Phase lag of the frequency response of a second order system to a sinusoidal forcing function
is 30°
is 90° at the most
approaches 180° asymptotically
is 120°
approaches 180° asymptotically
Dead zone in an instrument must be less than __________ percent of the scale.
0.2
1.5
4
8
0.2
Emission spectroscopy is used for
solids and metal analysis.
determining water purity.
determination of CO2 in gases.
NOxdetermination.
solids and metal analysis.
Gas analysis is commonly done using the
thermal conductivity cell
X-ray diffraction
mass spectrometer
emission spectrometer
thermal conductivity cell
The open loop transfer function of a control system is KR/(1 + TS). This represents
a first order system.
dead time system.
a first order time lag.
a second order system.
a first order system.
Thermal conductivity measurement is used for the determination of
O2 percentage in the flue gas.
specific gravity of petrofuels.
composition of an alloy.
CO2 percentage in the flue gas.
CO2 percentage in the flue gas.
Presence of a small amount of water in the organic systems can be determined by the __________ method.
electrical conductivity
polarimetry
emission spectroscopy
dielectric constant end loss factor
dielectric constant end loss factor
The transfer function of a pure dead time system with dead time τd is
1/(τds + 1)
τds + 1
e-τss
eτds
e-τss
Thermal conductivity cell is the primary element of a/an __________ analyser.
oxygen
carbon dioxide
carbon monoxide
sulphur dioxide
carbon dioxide
Zirconia probe is used for the measurement of
humidity of air.
% CO2 in flue gas.
% O2 in flue gas.
speed of a submarine.
% 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
-1
0
1
∞
∞
__________ type of element is normally not used in the bimetallic thermometers.
Flat spiral
Bourdon tube
Single helix
Multiple helix
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
8, 0.6, 0.08
12, 0.6, 0.12
8, 0.6, 0.12
12, 0.4, 0.08
12, 0.6, 0.12
Process degree of freedom indicates __________ number of controllers to be used.
the maximum
the minimum
both maximum and the minimum
nothing about the
the maximum
Characteristic equation is the denominator of __________ loop transfer function.
open
closed
both (a)and (b)
neither (a) nor (b)
closed
Operating range of a temperature measuring instrument is 800 to 1600°C. It could be a/an __________ pyrometer.
radiation
optical
photoelectric
none of these
photoelectric
Polarograph is meant for the analysis of
gaseous mixture
miscible liquids
solids
isotopes
solids
Which of the following fluid flow measuring devices can measure the largest flow rate?
V-notch
Rotameter
Orificemeter
Weir
Weir
Flow rate of sludge is not measured by a/an
orificemeter
open weir
kennison nozzle
both(b)&(c)
both(b)&(c)
In a shell and tube heat exchanger, the inlet temperature of heating/cooling fluid is the __________ variable.
load
manipulated
controlled
none of these
load
Polarisation of light forms the working principle of a
polarimeter
polarograph
chromatograph
spectrometer
polarimeter
A bimetallic thermometer as compared to industrial mercury in glass thermometer has almost the same
temperature measuring range (- 40°C to 450°C).
accuracy (± 1% of span).
speed of response.
all a, b & c.
all a, b & c.
Thermal wells used in temperature measurements should have
very thick walls.
low emissivity.
polished surface.
high transmissivity of radiation.
high transmissivity of radiation.
Which of the following flow-metering instruments is an areameter?
Venturimeter
Rotameter
Pitot tube
Hot wire anemometer
Rotameter
Out of the following themocouple wire insulating material, the highest temperature rating is for
teflon
ceramic fibre
asbestos
fibre glass
ceramic fibre
Which is the most suitable instrument for measuring pressure below 3 microns ?
Mcleoid gauge
Alphatron
Ionisation gauge
Bourdon guage
Ionisation gauge
Routh stability method uses __________ loop transfer function.
open
closed
either (a) or (b)
neither (a) nor (b)
closed
Pyrometry refers to the measurement of temperature
with the mercurial thermometer upto 350°C.
directly.
which is of higher magnitude.
all (a), (b) & (c).
which is of higher magnitude.
Photoelectric pyrometers are suitable in the temperature range of __________ °C.
400-1600
800-1600
800-2500
400-1000
800-1600
Non-metallic diaphragm used as pressure sensor in instruments is generally made of
teflon
synthetic rubber
bakelite
thick paper
synthetic rubber
Response of a linear control system for a change in set point is called
frequency response
transient response
servo problem
regulator problem
servo problem
Hot wire anemometer is used for the measurement of
flow rates of fluids.
flow rates of granular solids.
very high temperature.
thermal conductivity of gases.
flow rates of fluids.
Which of the following thermocouples has the widest temperature measurement range?
Iron-constantan
Chromel-alumel
Copper-constantan
Platinum-platinum/rhodium
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 direct acting.
air to close valve with the controller indirect acting.
air to open valve with the controller indirect acting.
air to close valve with the controller direct acting.
air to open valve with the controller indirect acting.
Bourdon tube is never made of
phosphor bronze
monel metal
stainless steel
cast iron
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
polarimeter
chromatograph
polarograph
pH meter
The term analogous to voltage in a single tank system is the
heat content of the system.
liquid volume in the tank.
flow rate.
level of liquid.
level of liquid.
In a shell and tube heat exchanger, the outlet temperature of heating/cooling fluid is the __________ variable.
load
manipulated
controlled
none of these
controlled
Mcleoid gauge is used to measure the
point velocity
flow rate
vacuum
pressure
vacuum
What is the Laplace transform of impulse input having magnitude ‘X’?
X
X^2
1/X
1
1
Thermocouple is suitable for measuring
liquid temperatures only.
very high temperatures only.
very low temperatures only.
both high and low temperatures.
both high and low temperatures.
Bimetal strips are not used in
bimetallic thermometers.
thermocouples.
thermostats.
relays for opening & closing of electrical circuits.
thermocouples.
When the damping co-efficient (ξ) is unity, the system is
Overdamped.
Critically damped.
Underdamped.
Highly fluctuating.
Critically damped.
Nickel percentage in invar which is an iron-nickel alloy, and is used as a thermocouple material is
12
36
54
68
36
Silver point temperature is __________ °C.
760.5
860.5
960.5
1060.5
960.5
A non-linear system will have __________ steady state values.
one
more than one
two
three
more than one
Which of the following is not a variable area flow meter?
Piston type meter
Rotameter
Magnetic flow meter
Orifice and tapered plug meter
Magnetic flow meter
With increase in temperature, the electrical conductivity of the platinum used in the resistance thermometer
increases
decreases
remains constant
increases exponentially
decreases
Sub-zero temperature (< 0°C) can be measured by a constant volume gas thermometer employing
helium
nitrogen
hydrogen
none of these
helium
__________ is an example of distributed parameter system.
Tubular reactor
CSTR
On-off controller
none of these
Tubular reactor
Which of the following is not classified as a thermo electric pyrometer?
Resistance thermometer.
Thermocouple.
Optical pyrometer (disappearing filament type)
Radiation pyrometer
Optical pyrometer (disappearing filament type)
Maximum differential pressure in liquid manometer is __________ psi.
20
30
40
50
30
Phase margin is equal to
180° - phase lag
phase lag - 180°
phase lag + 180°
phase lag + 90°
180° - phase lag
In a feed-back control system G and H denote open loop and close loop transfer functions respectively. The output-input relationship is
G/(1 + H)
H/(1 +G)
G/H
H/G
H/(1 +G)
Flow rate measurement of hostile acids and alkalis can be most suitably done by a/an
venturimeter
orificemeter
magnetic flow meter
hot wire anemometer
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
orsat apparatus
thermal conductivity cell
zirconia probe
chromatograph
thermal conductivity cell
Thermisters which have a very high temperature co-efficient of resistivity belong to the class of solid called
dielectrics
insulators
semi conductors
conductors
semi conductors
The pressure sensing element of elastic type pressure gauge is never made in the form of a
bellow
diaphragm
strip
Bourdon tube
strip
Liquid flow rate in an open channel can not be measured by a/an
orifice meter
cipolletti weir
rectangular weir
V-notch
orifice meter
The unit of ‘time constant’ of a system is the same as that of
velocity
time
(time)-1
none of these
time
Which of the following filled system expansion thermometers has the lowest positive temperature measurement capability?
Mercury in glass thermometer.
Alcohol in glass thermometer.
Fused metal (Na or K) in steel thermometer.
Nitrogen in steel thermometer.
Alcohol in glass thermometer.
Liquid column manometers are used for measuring the pressure __________ kgf/cm2 .
> 2(gage)
< 3 (gage)
< 10 (gage)
< atmospheric
< 3 (gage)
Cascade control means
feed forward control.
more than one feed-back loop.
on-off control.
one feed-back loop.
more than one feed-back loop.
The level of a liquid under pressure can be determined using
bubbler system
differential pressure manometer
diaphragm box system
air-trap system
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
emf produced is very low of the order of microvolt.
embrittlement of iron occurs.
rusting of iron takes place.
both (b) and (c).
both (b) and (c).
Which of the following is never used as an element of industrial resistance thermometer?
Lead
Nickel
Copper
30% iron + 70% nickel
Lead
Which of the following shows maximum dip effect (indicating reverse direction of temperature change)?
Mercury thermometer
Radiation pyrometer
Bimetallic thermometer
Thermocouple
Mercury thermometer
A stable system is the one
for which the output response is bounded for all bounded input.
which exhibits an unbounded response to a bounded input
which satisfies the conditions for a servo problem.
none of these.
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 function is exponential.
the Laplace transform of integral of exp(at) has finite values only for s > a.
the Laplace transform integral of exp(at) has initial values only for s > a.
the function exp(at) is piece-wise continuous only for s > a.
the Laplace transform of integral of exp(at) has finite values only for s > a.
Meleoid gauge measures the __________ pressure.
positive
sub-atmospheric
very high
atmospheric
sub-atmospheric
Which of the following thermocouples is capable of measuring a temperature of -50°C?
Platinum - platinum + rhodium
Chromel - alumel
Iron-constantan
Copper - constantan
Platinum - platinum + rhodium
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
1064.43
1261.93
630.74
Change of angle of refraction with composition comprises the working principle of a
polarimeter
polarograph
spectrometer
refractrometer
refractrometer
Which of the following instruments is not used for measuring sub-zero (<0°) temperatures?
Platinum resistance thermometer
Mercury in glass thermometer
Vapor pressure thermometer
Radiation pyrometer
Radiation pyrometer
Which of the following is not suitable for measuring the temperature of a red hot object in the range of 800 - 1600°C ?
Optical pyrometer
Radiation pyrometer
Photoelectric pyrometer
Thermocouples
Thermocouples
Flame photometry is used for the determination of compositional analysis of
solids
alkali metals
natural gas
isotopes
alkali metals
Reference points i.e., ice point and steam point in Reaumer temperature scale are respectively
- 273° & 80°
0° & 80°
32° & 460°
32° & 80°
0° & 80°
Which of the following is not a composition measuring instrument?
Thermal conductivity cell
Mass spectrometer
Polarograph
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
iron-constantan
platinum-platinum+rhodium
none of these.
chromel-alumel
Which of the following thermocouples is incapable of measuring sub-zero (i.e., < 0°C) temperature?
Chromel-alumel
Iron-constantan
Platinum-platinum + rhodium
Copper-constantan
Platinum-platinum + rhodium
Platinum resistance thermometer is the international standard for temperature measurement between
triple point of hydrogen and freezing point of antimony
13.81°K to 903.9°K
both (a) and (b)
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.
100
75
25
0
0
The thermal emf-temperature relationship of most thermocouples is
linear
parabolic
exponential
square root
parabolic
Which is the strongest paramagnetic gas?
CO2
O2
NO
NO2
O2
In Bode plot, A.R. vs. w is plotted on a/an __________ graph paper.
log-lag
triangular
ordinary
semi-log
log-lag
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
0.5
1/sqrt(2)
0.25
1/sqrt(2)
For measuring the temperature of a red hot furnace, which is the most suitable instrument?
Platinum resistance thermometer
Thermocouple
Optical pyrometer
Bimetallic thermometer
Optical pyrometer
Continuous measurement of specific gravity of a liquid is done by
hydrometer
contact-type electric indicators
displacement meter
both (a) and (c)
both (a) and (c)
Stroboscope is used for the measurement of
rpm of a flywheel
frequency of light
depression of freezing point
liquid level under pressure
rpm of a flywheel
In second order underdamped system,
decay ratio = overshoot
decay ratio = (overshoot)^2
overshoot increases for increasing damping co-efficient.
large damping co-efficient means smaller damping.
decay ratio = (overshoot)^2
Dome temperature of blast furnace stove is most accurately measured by a
radiation pyrometer.
platinum-platinum/rhodium ther-mocuple.
iron-constantan thermocouple.
platinum resistance thermometer.
platinum-platinum/rhodium ther-mocuple.
Phase lag of the sinusoidal response of a first order system is
120°
30°
180°
90°
90°
Continuous measurement of moisture content of paper in paper industry is done by measuring the
thermal conductivity through the paper
electrical resistance through the paper
magnetic susceptibility
none of these
electrical resistance through the paper
Thermal well made of __________ gives the fastest speed of response, while measuring temperature by thermocouples.
steel
vycor (a glass)
nichrome
inconel
vycor (a glass)
Pick out the wrong statement.
There is no transfer lag for a single first order system.
Stirred tank with a water jacket exemplifies an interacting system.
Transfer lag is a characteristics of all higher order systems (other than first order systems).
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.
pressure rise with temperature.
linear expansion.
none of these.
volumetric expansion.
The frequency at which maximum amplitude ratio is attained is called the __________ frequency.
corner
resonant
cross-over
natural
resonant
Which of the following can measure temperatures in the range of - 20 to 300°C ?
Mercury in glass thermometer
Vapor pressure thermometer
Resistance thermometer
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 controller.
proportional-derivative(PD)controller.
proportional-integral (PI) controller.
proportional integral-derivative (PID) controller.
proportional integral-derivative (PID) controller.
Conversion formula for converting amplitude ratio (AR) into decibels is
Decibel = 20 log 10 (AR)
Decibel = 20 log e (AR)
Decibel = 20 log 10 (AR)^0.5
Decibel = 20 log e (AR)^0.5
Decibel = 20 log 10 (AR)
A manometer measures the __________ pressure.
atmospheric
absolute
gauge
none of these
gauge
Normal mercury thermometer can be used to measure a temperature of about 300°C. However, its maximum temperature measurement range can be increased upto about 500°C by
filling nitrogen under pressure in the stem.
increasing the diameter of the tube.
using steel tube in place of glass tube.
accounting for the tube expansion.
filling nitrogen under pressure in the stem.
Minute depression of freezing point of a liquid solvent on addition of a solid solute can be best measured by a
Beckman thermometer
dilatometer
mercury thermometer
bimetallic thermometer
Beckman thermometer
Temperature of __________ can not be measured by an optical or radiation pyrometer.
hot blast (air) from stoves
molten slag flowing out of blast furnace
combustion space in boilers
rotary limestone calcination kiln
hot blast (air) from stoves
Gain margin is equal to the
amplitude ratio
reciprocal of amplitude ratio
gain in P controller
gain in P-I controller
reciprocal of amplitude ratio
A system with transfer function 2S/4S + 1 is of __________ order.
zero
1st
2nd
3rd
1st
In Bode plot, Φ vs ω is plotted on a/an __________ graph paper.
log-log
ordinary
semi-log
triangular
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
chromel-alumel thermocouple
optical pyrometer
radiation pyrometer
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
ratio
sum
difference
product
Ordinary mercury in glass thermometer is used for measuring temperature upto 120°C. However, for measuring higher temperature upto __________ °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.
250
350
550
700
550
Mercury thermometer is commonly used for low temperature measruement. The freezing point and boiling point of mercury are respectively __________ °C.
- 39 and 350
- 51 and 439
- 79 and 395
- 10 and 425
- 39 and 350
Which of the following thermocouples has the least temperature measurement range?
Copper-constantan
Chromel-alumel
Platinum-platinum/rhodium
Iron-constantan
Copper-constantan
Composition of natural gas is determined by the
Haldane apparatus
mass spectrometer
chromatograph
both (b) and (c)
both (b) and (c)
