Process Control and Instrumentation Flashcards
(345 cards)
1
Q
Which of the following is an undesirable dynamic characteristic of an instrument ?
A
Time lag
2
Q
Which of the following is not the triple point of water ?
A
32°R
3
Q
Pick out the one which is a first order instrument.
A
All (a), (b) and (c).
4
Q
Load cells are used for the measurement of
A
weight
5
Q
Which of the following is the dynamic characteristics of an instrument ?
A
Fidelity
6
Q
Pick out the wrong statement.
A
CO2 is the strongest paramagnetic gas.
7
Q
The __________ of a vapor pressure thermometer is a functioning element.
A
pointer
8
Q
A negative gain margin expressed in decibels means a/an __________ system.
A
unstable
9
Q
Thermistor, which has high temperature co-efficient of resistivity, is used as the sensing element in resistance thermometer. It is a/an
A
solid semi-conductor
10
Q
Flapper nozzle is used in a/an __________ controller.
A
pneumatic
11
Q
Typical specifications for design stipulates the gain margin and phase margin to be respectively
A
> 1.7 and > 30°
12
Q
Working principle of radiation pyrometer is based on the
A
Stafan-Boltzman law
13
Q
Which of the following relates the emf. generated in a single homogeneous wire to the temperature difference ?
A
Thomson effect
14
Q
Dilute wine was used as a thermometric liquid initially to develop temperature scale. First emperical temperature scale developed was the __________ scale.
A
Fahrenheit
15
Q
In a single tank system, the transfer function of level to inlet flow rate is
A
R/(TS + 1)
16
Q
Which of the following is a desirable characteristic of an instrument ?
A
High fidelity
17
Q
The operation of a rotameter is based on
A
variable flow area.
18
Q
The temperature of tempering oil baths maintained at 400°C during heat treatment of steel is measured by a/an __________ thermocouple.
A
iron-constantan
19
Q
Instrumentation in a plant offers the advantage of
A
all (a), (b) and (c)
20
Q
Which of the following temperature measuring instruments need not touch the object whose temperature is being measured ?
A
Radiation/infrared pyrometer
21
Q
Thermal conductivity measurement com-prises the working principle of a
A
CO2 analyser
22
Q
Response of a system to a sinusoidal input is called __________ response.
A
frequency
23
Q
The closed loop pole of a stable second order system could be
A
both real and negative.
24
Q
Smoke density of the flue gas going out of the chimney is measured by a
A
photo electric cell
25
Transfer function of transportation lag is
e-TS
26
Temperature measuring instruments are standardised mostly with __________ points of pure substances.
both (a) & (b)
27
Pick out the first order system from among the following.
Mercury in glass thermometer kept in boiling water.
28
The maximum service temperature for fibre glass used as thermocouple wire insulation material is __________ °C.
500
29
Which of the following controllers has the least maximum deviation ?
P-D controller
30
Volumetric expansion is the working principle of the __________ thermometers.
mercury in glass
31
Which of the following measurements can be made by the measurement of emf ?
All (a), (b) & (c)
32
A magnetic flowmeter is
all (a), (b) and (c).
33
Zirconia probe is used for the continuous measurment of __________ flue gases going out of the furnace.
oxygen in
34
Strain gage pressure transducers are used to measure __________ pressures.
both (a) and (b)
35
The transfer function for a PID controller is (where, τ i is the integral (reset) time and τD is the derivative time.)
36
Compositional analysis of __________ is done using mass spectrometer.
an isotope
37
The function of a transducer is to
convert the primary signal into a more useful quantity, usually an electric impulse.
38
Nichol's chart deals with
closed loop values vs. open loop values.
39
Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature ?
Chromel-constantan.
40
A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if
Kc is reduced.
41
The symbol for "capillary line" in instrumentation diagram is
42
__________ is undesirable in thermocouples used in industries,
Non-linear relation of emf to temperature
43
Select the correct statement from the following.
The amplitude ratio of a pure capacity process is inversely proportional to frequency.
44
For an input forcing function, X(t) = 2t2, the Laplace transform of this function is
4/s3
45
Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a
thermocouple
46
The __________ of a vapor pressure thermometer is a secondary element.
Bourdon tube
47
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
48
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
49
The second order system with the transfer function 4/s^2+2s+4 has a damping ratio of
0.5
50
In a shell and tube heat exchanger, the flow rate of heating/cooling fluid is the __________ variable.
manipulated
51
A non-linear chemical system is exemplified by a/an
non-isothermal CSTR
52
The transfer function for an ideal proportional plus reset controller (reset time T) is
Kc(1+ 1/TS)
53
The frequency response of a first order system, has a phase shift with lower and upper bounds given by
0, π/2
54
Gas chromatography is used for the measurement of
concentration
55
Which of the following thermocouples can measure the maximum temperature ?
Tungsten-molybdenum
56
Radiation pyrometers as compared to thermocouples
can measure higher temperature.
57
Liquid flow rate in a small channel is best measured by a/an
pitot tube
58
Specific gravity of a liquid can not be measured by a/an
anemometer
59
__________ temperature scale assigns 0° to the 'ice point' and 80° to the 'steam point'.
Reumur
60
Dead zone is the
maximum change in the variable that does not change the reading of the instrument.
61
Which of the following thermometers is not suitable for distant reading upto 60 metres?
Mercury in glass thermometer
62
Degree to which an instrument indicates the changes in measured variable without dynamic error is called its
fidielity
63
Thermistors are made of
metal oxides
64
A barometer measures the __________ pressure.
absolute
65
Humidity of air can be determined by a
sling psychrometer
66
Thermocouple in a thermal well behaves as a true
multiple first order system.
67
The transfer function for a P-D controller is
Kc(1+τD s)
68
Bode diagram is a plot of
log (AR) vs. log (f) and (Φ) vs. log (f).
69
Working principle of disappearing filament type optical pyrometer is based on the
Wien's law
70
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
71
Pick out the wrong statement
CSTR can be considered as a distributed parameter system.
72
Range of hydrogen gas constant volume themometer is __________ °C.
0 to 100
73
The initial value (t=0) of the unit step response of the transfer function [(s + 1)/(2s + 1)] is
1/2
74
The __________ of a vapor pressure thermometer is a primary element.
bulb
75
The time constant of a first order process with resistance R and capacitance C is
RC
76
A sinusoidal variation in the input passing through a linear first order system
gets attenuated (magnitude decreases).
77
Nitrogen gas constant volume thermometer is suitable for measuring a temperature of __________ °C.
> 100
78
What is the overall transfer function (C/R) of the following block diagram if G = G1. G2. G3 and H = H1.H2.
G/1+GH
79
Pick out the most suitable instrument for measuring temperature in the range of-40 to 425°C.
bimetallic thermometer
80
Accurate temperature measurement performance of a radiation pyrometer can not be affected, if the
object and surrounding are at almost the same temperature.
81
Relationship between absorption/evolution of heat at the thermocouple junctions and the current flow in the circuit is given by __________ effect.
Peltier
82
Configuration of Bourdon spring tube is never made of __________ shape.
circular
83
Thermodynamic celcius scale of temperature measurement is
both (b) and (c)
84
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°
85
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.
86
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
87
Measurement of pressure in ammonia reactor is done by
Bourdon gauge
88
The fluid used in hydraulic controller is
oil
89
Flow rate of a river is measured by a/an
vane meter
90
Which of the following thermocouple materials does not contain nickel ?
None of these.
91
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
92
Identify an unbounded input from inputs whose transfer functions are given below
1/S^2
93
"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
94
Feed forward controller accounts for the __________ changes.
load
95
Which thermocouple can be used to measure a temperature of around 1400°C ?
Platinum-platinum+rhodium
96
Which of the following filled system expansion thermometer has the capability to measure the lowest temperature ?
Alcohol in glass thermometer
97
Concentration of sugar solution can be determined by the
polarimetry
98
In a single tank system, the transfer function of __________ to inlet flow rate is 1/TS+1.
outlet flow rate
99
Which of the following can not measure a temperature of 1600°C ?
Platinum resistance thermometer
100
The temperature range for which copper resistance thermometer can be used is __________ °C
-200 to 150
101
Paramagnetism method is not used for the composition determination of __________ in gases.
carbon dioxide
102
An amplitude ratio of 0.1 corresponds to __________ decibels.
-20
103
For increased speed of response of an expansion pressure spring thermometer, the thermometer bulb should have a
all'a', 'b' & 'c'.
104
Pressure of 0.0001 absolute psi can be measured by __________ gauge.
Mcloid
105
Pirani gauge is used for the measurement of
high vacuum.
106
The __________ of the fluid contained in the temperature sensing element (i.e., bulb) of filled system thermometers changes with change in temperature.
all (a), (b) and (c)
107
Transfer functions X/Y for which of the following block diagrams is
108
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
all 'a', 'b' & 'c'
109
__________ thermometer can not measure sub-zero (< 0° C) temperature,
Bimetallic
110
Starting temperature of optical radiation pyrometer is __________ °C.
800
111
Liquid argon level in a pressurised storage tank (at 3 kg/cm2 ) is measured by a/an
differential pressure gage
112
Which of the systems having following transfer functions is stable?
1/(s2 + 2s + 2)
113
What is the dynamic error in a critically damped second order instrument for a ramp input (At) ?
2 AT
114
The transfer function for a first order process with time delay is
115
An ideal PID controller has the transfer function . The frequency at which the magnitude ratio of the controller is 1, is
1/sqrt(0.2 x 0.5)
116
The deflection of the free end of the bimetallic strips in a bimetallic thermometer with temperature is nearly
linear
117
Alphatron measures pressure __________ microns.
> 3
118
What is the ratio of output amplitude to input amplitude for a sinusoidal forcing function in a first order system ?
< 1
119
The unit step response of the transfer functionreaches its final steady state assymptotically after
a monotonic increase.
120
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
1/s (1+2/s)
121
The term analogous to the electrical current in a thermal system is the
heat flow rate
122
Reset rate is the another term used for __________ time.
integral
123
Continuous measurement of moisture in paper is done by
high resistance Wheatstone's bridge circuit.
124
Psychrometer determines the
humidity of gases
125
Which of the systems having the following transfer function is stable ?
1/s^2+2S+2
126
The calibration data of a thermocouple with its cold junction at 0°C are given below.
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 ?
2.46 mv
127
A mercury barometer measures the __________ pressure.
atmospheric
128
Positioning controllers are used for
high loads
129
The amplitude ratio for the sinusoidal response of a __________ is 1.
transportation lag
130
The response of two tanks of same size and resistance in series is
critically damped
131
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
132
The amplitude ratio for the sinusoidal response of __________ is < 1.
first order system
133
Which of the following is a 'contact' pyrometer ?
resistance pyrometer
134
Which of the following is not a speed measuring instrument ?
Psychrometer
135
Measurement of sub-zero Celcius temperature in industry is done most commonly by
resistance thermometers
136
For the block diagram shown below :
The characteristic equation is1
τl S(τm S + 1) (τp S + 1) +Kc . Kp . Km (τl s + 1) e-τdS = 0
137
Use of I-control along with P-control facilitates
elimination of offset
138
Turbine flow meters are suitable for
both (b) and (c).
139
Liquid discharge from a tank or reservoir can not be measured by
orificemeters
140
Which of the following is not a mechanical pressure sensing element ?
U-tube
141
__________ are analysed using a polarograph.
Solids
142
Which of the following judges the accuracy of an instrument ?
Static error
143
On-off controllers are normally used for
low loads
144
Magnetic flowmeters are generally not used for the velocity/flow measurement of hydrocarbons due to their
low electrical conductivity.
145
Which of the following controllers has maximum offset ?
P-controller
146
Pressure of 0.01 psi (absolute) can be measured by __________ gauge.
Mcloid
147
High temperature of around 2000°C of incandescent gas mantles is measured by a/an
radiation pyrometer.
148
The unit step response of the transfer function 1/(s2 + 2s + 3)
has a damped oscillatory characteristics.
149
The experimental response of the controlled variable y(t) for a step change of magnitude P in the manipulated variable x(t) is shown below :
The appropriate transfer function of the process is
150
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
151
Which of the following does not figure in the list of seven substances selected for international temperature scale ?
Zinc (B.P) and mercury (F.P
152
A constant volume gas thermometer employing __________ is used to measure sub-zero (i.e., < 0° C) temperature.
helium
153
pH meter has
two cells
154
Routh test
cannot be used to test the stability of a control system containing transportation lag.
155
The open loop transfer function of a process is . In the root locus diagram, the poles will be at
-2, -3
156
Water is entering a storage tank at a temperature T0 and flow rate Q0 and leaving at a flow rate Q and temperature T. There are negligible heat losses in the tank. The area of cross-section of the tank is A0. The model that describes the dynamic variation of temperature of water in the tank with time is given as :
Q0(T0 - T) = Ac . h dT/dt
157
When a bare thermocouple is covered by a protective sheath, the response becomes
slower and non-oscillatory.
158
What is the normal percentage of rhodium in platinum + rhodium element used in the thermocouple ?
13
159
Helium gas constant volume thermometer is suitable for the measurement of a temperature of __________ °C.
< 0
160
The transfer function of a second order system is
161
Bode diagram are generated from output response of the system subjected to which of the following input?
Sinusoidal
162
Which of the following thermocouples is the most suitable for measuring a temperature of about 1600°C in an oxidizing atmosphere ?
Platinum-platinum + rhodium
163
Mercury thermometer can be used to measure the temperature upto __________ °C.
350
164
The transfer function of a process is . If a step change is introduced into the system, then the response will be
under damped
165
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
all 'a', 'b' & 'c'.
166
Which of the following is not a differential pressure flow meter ?
Rotameter
167
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 ?
Mercury
168
Bourdon gauges are used for measuring pressure (kg/cm2 )
> 2 (gauge)
169
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
170
A typical example of a physical system with under damped characteristic is a
spring loaded diaphragm valve.
171
An aneroid barometer measures the __________ pressure.
absolute
172
A bolometer is
both (a) & (b).
173
Thermal wells are used in the temperature measurement to
guard against corrosive and oxidising action on thermocouple materials
174
The offset introduced by proportional controller with gain Kcin response of first order system can be reduced by
introducing integral control.
175
A system with a double pole at the origin is unstable since the corresponding term in the time domain
grows linearly with time.
176
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
177
In a second order under damped system, the
overshoot (which is a measure of how much the response exceeds the ultimate value) increase with the decrease of damping co-efficient e.
178
In an exothermic chemical reactor, the manipulated variable is the flow rate of
coolant
179
Very low pressure is expressed in microns(μ), which is equal to __________ mm of Hg coloumn (absolute) at 0°C.
0.001
180
The inverse Laplace transform of the function is
1 - e^-t
181
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
182
Emf generated in a thermocouple depends on the temperature
difference between hot and cold junctions.
183
Working principle of mercury in glass thermometer is based on the __________ of mercury with increase in temperature.
volumetric expansion
184
The Laplace transform of a sinusoidal function (eg; sin at) is represented by the curve
185
Number of poles in a system with transfer function is
3
186
Radiation thermometer can not measure the temperature
of liquid oxygen.
187
Temperature measurement by optical pyrometer is done above __________ point, which is 1063°C.
gold
188
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
189
Dilatometer is used to measure
contraction/expansion due to changes in temperature
190
Mass spectrometer is used for the composition analysis of
isotopes
191
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°
192
__________ stability method uses open loop transfer function.
Nyquist
193
A pyranometer is an instrument used for measuring the
global radiation.
194
All the thermocouples used for temperature measurement use dissimilar metal
wires
195
The transfer function of a first order system is
1 /Ts+1
196
Composition of alloys can be determined by
polarograph
197
Optical activity of a solution can be determined using a
polarimeter
198
Stability of a control system containing a transportation lag can be best analysed by
frequency response methods
199
Stabilising time for the controllers is the time required for the response to reach __________ percent of its ultimate value.
95
200
Time constant is the
time taken by the controlled variable to reach 63.2% of its full change.
201
Mercury manometer (U-tube type) exemplifies a __________ order system.
second
202
Emf developed by a thermocouple while measuring a temperature of 400°C is 22 mV. The type of thermocouple used is
iron-constantan
203
Bode stability method uses __________ loop transfer function.
open
204
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
205
Which of the following is not a second order instrument ?
Bare mercury in glass thermometer.
206
Small furnace draught is accurately measured by an inclined tube manometer, in which the manometric liquid used most commonly is
paraffin
207
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.
1
208
A simple pitot tube measures the
static pressure
209
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.
210
A mercury thermometer can not be used to measure the temperature below the freezing point of mercury, which is __________ °C.
-38.9
211
__________ controller has the maximum stabilising time.
PI
212
Out of the following temperature measuring instruments, the measurement accuracy will be minimum for the
optical pyrometer.
213
Stalagmometer is used for the measurement of
surface tension
214
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^4
215
Working principle of radiation pyrometer is based on the
stefan-Boltzman law
216
Liquid levels in autocalves are measued by
differential float type manometer
217
E.m.f. generated by thermocouples is of the order of
millivolts
218
A pyrheliometer is an instrument used for measuring the
beam radiation.
219
Flow rate through an orifice is __________ the pressure differential.
proportional to the square root of
220
Thermistors are used in __________ devices.
both(b)&(c)
221
__________ is the static characteristics of an instrument,
Drift
222
Phase lag of the frequency response of a second order system to a sinusoidal forcing function
approaches 180° asymptotically
223
Dead zone in an instrument must be less than __________ percent of the scale.
0.2
224
Emission spectroscopy is used for
solids and metal analysis.
225
Gas analysis is commonly done using the
thermal conductivity cell
226
The open loop transfer function of a control system is KR/1+TS. This represents
a first order system.
227
Thermal conductivity measurement is used for the determination of
CO2 percentage in the flue gas.
228
Presence of a small amount of water in the organic systems can be determined by the __________ method.
dielectric constant end loss factor
229
The transfer function of a pure dead time system with dead time τd is
e^-τss
230
Thermal conductivity cell is the primary element of a/an __________ analyser.
carbon dioxide
231
Zirconia probe is used for the measurement of
% O2 in flue gas.
232
The root locus method, a pole of a transfer function G(s) is the value of s for which G(s) approaches
∞
233
__________ type of element is normally not used in the bimetallic thermometers.
Bourdon tube
234
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
235
Process degree of freedom indicates __________ number of controllers to be used.
the maximum
236
Characteristic equation is the denominator of __________ loop transfer function.
closed
237
Operating range of a temperature measuring instrument is 800 to 1600°C. It could be a/an __________ pyrometer.
photoelectric
238
Polarograph is meant for the analysis of
solids
239
Which of the following fluid flow measuring devices can measure the largest flow rate ?
Weir
240
Flow rate of sludge is not measured by a/an
both(b)&(c)
241
In a shell and tube heat exchanger, the inlet temperature of heating/cooling fluid is the __________ variable.
load
242
Which of following error integral is considered as the best criterion in controller settings ?
243
Polarisation of light forms the working principle of a
polarimeter
244
A bimetallic thermometer as compared to industrial mercury in glass thermometer has almost the same
all a, b & c.
245
Thermal wells used in temperature measurements should have
high transmissivity of radiation.
246
Which of the following flow-metering instru-ments is an areameter ?
Rotameter
247
Out of the following themocouple wire insulating material, the highest temperature rating is for
ceramic fibre
248
Which is the most suitable instrument for measuring pressure below 3 microns ?
Ionisation gauge
249
Routh stability method uses __________ loop transfer function.
closed
250
Pyrometry refers to the measurement of temperature
which is of higher magnitude.
251
Photoelectric pyrometers are suitable in the temperature range of __________ °C.
800-1600
252
Non-metallic diaphragm used as pressure sensor in instruments is generally made of
synthetic rubber
253
Response of a linear control system for a change in set point is called
servo problem
254
Hot wire anemometer is used for the measurement of
flow rates of fluids.
255
Which of the following thermocouples has the widest temperature measurement range ?
Platinum-platinum/rhodium
256
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.
257
Bourdon tube is never made of
cast iron
258
"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
259
Pick out the symbol for "locally mounted instrument" in instrumentation diagram.
O
260
Block diagram of a simple standard control system is shown below in the figure.
Which of the following statement about the above control system is wrong ?
Manipulated variable is represented by C.
261
Water is flowing through a series of four tanks and getting heated as shown in figure. It is desired to design a cascade control scheme for controlling the temperature of water leaving the tank 4 as there is a disturbance in the temperature of a second stream entering the tank 2. Select the best place to take the secondary measurement for the second loop.
Tank 3
262
The term analogous to voltage in a single tank system is the
level of liquid.
263
In a shell and tube heat exchanger, the outlet temperature of heating/cooling fluid is the __________ variable.
controlled
264
Mcleoid gauge is used to measure the
vacuum
265
What is the Laplace transform of impulse input having magnitude 'X' ?
1
266
Thermocouple is suitable for measuring
both high and low temperatures.
267
Bimetal strips are not used in
thermocouples
268
When the damping co-efficient (ξ) is unity, the system is
Critically damped.
269
Nickel percentage in invar which is an iron-nickel alloy, and is used as a thermocouple material is
36
270
Which is the symbol for "pneumatic control valve" ?
271
Silver point temperature is __________ °C.
960.5
272
A non-linear system will have __________ steady state values.
more than one
273
Which of the following is not a variable area flow meter ?
Magnetic flow meter
274
With increase in temperature, the electrical conductivity of the platinum used in the resistance thermometer
decreases
275
Sub-zero temperature (< 0°C) can be measured by a constant volume gas thermometer employing
helium
276
__________ is an example of distributed parameter system
Tubular reactor
277
Which of the following is not classified as a thermo electric pyrometer ?
Optical pyrometer (disappearing filament type)
278
Maximum differential pressure in liquid manometer is __________ psi.
30
279
Phase margin is equal to
180° - phase lag
280
In a feed-back control system G and H denote open loop and close loop transfer functions respectively. The output-input relationship is
H/1+G
281
Flow rate measurement of hostile acids and alkalis can be most suitably done by a/an
magnetic flow meter
282
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
283
Thermisters which have a very high temperature co-efficient of resistivity belong to the class of solid called
semi conductors
284
The pressure sensing element of elastic type pressure gauge is never made in the form of a
strip
285
Liquid flow rate in an open channel can not be measured by a/an
orifice meter
286
The unit of 'time constant' of a system is the same as that of
time
287
Which of the following filled system expansion thermometers has the lowest positive temperature measurement capability ?
Alcohol in glass thermometer.
288
Liquid column manometers are used for measuring the pressure __________ kgf/cm2 .
< 3 (gage)
289
Cascade control means
more than one feed-back loop.
290
The level of a liquid under pressure can be determined using
differential pressure manometer
291
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
both (b) and (c).
292
Which of the following is never used as an element of industrial resistance thermometer ?
Lead
293
Which of the following shows maximum dip effect (indicating reverse direction of temperature change) ?
Mercury thermometer
294
A stable system is the one
for which the output response is bounded for all bounded input.
295
The Laplace transform of exp(at), where a > 0, is defined only for the Laplace parameter, s > a since
the Laplace transform of integral of exp(at) has finite values only for s > a.
296
Meleoid gauge measures the __________ pressure.
sub-atmospheric
297
Which of the following thermocouples is capable of measuring a temperature of -50°C?
Platinum - platinum + rhodium
298
Find the ultimate gain and frequency for a proportional controller in the case of a process having the transfer function Gp(s) = 1/(4s + 1)(2s + 1)(s + 1).
w = sqrt 7/6, Kc = 46/3
299
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.
630.74
300
Change of angle of refraction with composition comprises the working principle of a
refractrometer
301
Which of the following instruments is not used for measuring sub-zero (<0°) temperatures ?
Radiation pyrometer
302
Which of the following is not suitable for measuring the temperature of a red hot object in the range of 800 - 1600°C ?
Thermocouples
303
Find the Laplace transform of the following input function shown in figure.
304
Flame photometry is used for the determination of compositional analysis of
alkali metals
305
Reference points i.e., ice point and steam point in Reaumer temperature scale are respectively
0° & 80°
306
Which of the following is not a composition measuring instrument ?
Hot wire anemometer
307
Emf developed by a thermocouple while measuring a temperature of 800°C is about 31 mV. The type of thermocouple used is
chromel-alumel
308
Which of the following thermocouples is incapable of measuring sub-zero (i.e., < 0°C) temperature ?
Platinum-platinum + rhodium
309
Platinum resistance thermometer is the international standard for temperature measurement between
both (a) and (b)
310
0n-off control which is a special case of proportional control, has a band width of about __________ percent.
0
311
The thermal emf-temperature relationship of most thermocouples is
parabolic
312
Which is the strongest paramagnetic gas?
O2
313
In Bode plot, A.R. vs. w is plotted on a/an __________ graph paper.
log-lag
314
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/sqrt2
315
A control system has the following transfer function
The initial value of the corresponding time function is
1
316
For measuring the temperature of a red hot furnace, which is the most suitable instrument ?
Optical pyrometer
317
Continuous measurement of specific gravity of a liquid is done by
both (a) and (c)
318
Stroboscope is used for the measurement of
rpm of a flywheel
319
The root locus plot of the roots of the characteristics equation of a closed loop system having the open loop transfer function will have a definite num-ber of loci for variation of K from 0 to ∞. The number of loci is
3
320
In second order underdamped system,
decay ratio = (overshoot)2
321
Dome temperature of blast furnace stove is most accurately measured by a
platinum-platinum/rhodium ther-mocuple.
322
Phase lag of the sinusoidal response of a first order system is
90°
323
Continuous measurement of moisture content of paper in paper industry is done by measuring the
electrical resistance through the paper
324
Thermal well made of __________ gives the fastest speed of response, while measuring temperature by thermocouples.
vycor (a glass)
325
What is the Laplace transform of sin t ?
1/s^2+1
326
Pick out the wrong statement.
Transfer lag decreases as the number of stages decreases.
327
Working principle of mercury in glass thermometer is
volumetric expansion.
328
The frequency at which maximum amplitude ratio is attained is called the __________ frequency.
resonant
329
Which of the following can measure temperatures in the range of - 20 to 300°C ?
None of these.
330
If response of a control system is to be free of offset and oscillation, the most suitable controller is
proportional integral-derivative (PID) controller.
331
Conversion formula for converting amplitude ratio (AR) into decibels is
Decibel = 20 log10 (AR)
332
A manometer measures the __________ pressure.
gauge
333
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.
334
Minute depression of freezing point of a liquid solvent on addition of a solid solute can be best measured by a
Beckman thermometer
335
For the time domain function f(t) = t, the Laplace transform of is given by
1/S3
336
Temperature of __________ can not be measured by an optical or radiation pyrometer.
hot blast (air) from stoves
337
Gain margin is equal to the
reciprocal of amplitude ratio
338
A system with transfer function is of __________ order.
1st
339
In Bode plot, Φ vs ω is plotted on a/an __________ graph paper.
log-log
340
Temperature of molten pig iron (1450°C) and molten slag (1500°C) flowing out of a blast furnace is measured by a/an
either (b) or (c)
341
For two non-interacting first order systems connected in series, the overall transfer function is the __________ of the individual transfer functions.
product
342
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.
550
343
Mercury thermometer is commonly used for low temperature measruement. The freezing point and boiling point of mercury are respectively __________ °C.
- 39 and 350
344
Which of the following thermocouples has the least temperature measurement range?
Copper-constantan
345
Composition of natural gas is determined by the
both (b) and (c)
