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process ctrl inst > section 4 > Flashcards

section 4 Flashcards

1
Q

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
a. 5π/12
b. π/6
c. π/12
d. π/3

A

a

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2
Q

Which of the following does not figure in the list
of seven substances selected for international
temperature scale?
a. Ice (F.P) and steam (B.P)
b. Oxygen and sulphur (B.P)
c. Antimony and silver (F.P)
d. Zinc (B.P) and mercury (F.P)

A

d

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3
Q

A constant volume gas thermometer employing
__________ is used to measure sub-zero (i.e., <
0°C) temperature.
a. Helium
b. Hydrogen
c. Nitrogen
d. none of these

A

a

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4
Q

pH meter has
a. one cell
b. two cells
c. three cells
d. no cell

A

b

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5
Q

Routh test
1. criterion provides information about the
actual location of roots.
2. cannot be used to test the stability of a
control system containing transportation
lag.
3. criterion is not applicable to systems with
polynomial characteristic equation.
4. can not determine as to how many roots of
the characteristics equation have positive
real roots.

A

2

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6
Q

The open loop transfer function of a process is
K∙ (ss+1)(ss+4)/(ss+2)(ss+3) . In the root locus diagram, the poles
will be at
1. -1, -4
2. 1, 4
3. -2, -3
4. 2, 3

A

3

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7
Q

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:

a. Q0(T0 - T) = Ac .
b. Q0T0 - QT = Ac .
c. Q(T0 - T) = Ac .
d. Q(T0 - T) = Ac .

A

a

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8
Q

When a bare thermocouple is covered by a
protective sheath, the response becomes
a. faster and oscillatory.
b. faster and non-oscillatory.
c. slower and oscillatory.
d. slower and non-oscillatory.

A

d

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9
Q

What is the normal percentage of rhodium in
platinum + rhodium element used in the
thermocouple?
a. 0.1
b. 3
c. 13
d. 29

A

c

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10
Q

Helium gas constant volume thermometer is
suitable for the measurement of a temperature of
__________ °C.
a. < 100
b. < 0
c. > 0
d. > 800

A

b

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11
Q

The transfer function of a second order system
is

a.1/T2s2+2ξTs+1
b. 1/T2s2+2Ts+1
c.1/T2s2+2ξT+1
d. None of these

A

a

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12
Q

Bode diagram are generated from output
response of the system subjected to which of the
following input?
a. Impulse
b. Step
c. Ramp
d. Sinusoidal

A

d

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13
Q

Which of the following thermocouples is the
most suitable for measuring a temperature of about
1600°C in an oxidizing atmosphere?
a. Platinum-platinum + rhodium
b. Iron-constantan
c. Copper-constantan
d. Chromel-alumel

A

a

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13
Q

The transfer function of a process is . If
a step change is introduced into the system, then the
response will be
a. under damped
b. critically damped
c. over damped
d. none of these

A

a

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13
Q

Mercury thermometer can be used to measure
the temperature up to __________ °C.
a. 100
b. 250
c. 350
d. 750

A

c

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14
Q

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
a. making the volume of thermometer bulb as
large as conveniently possible.
b. reducing the volume of the capillary to a
minimum.
c. reducing the volume of the receiving
element to a minimum.
d. all ‘a’, ‘b’ & ‘c’.

A

d

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15
Q

Which of the following is not a differential
pressure flow meter?
a. Rotameter
b. Flow nozzle
c. Orificemeter
d. Venturimeter

A

a

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16
Q

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?
a. Water
b. Mercury
c. Methyl alcohal
d. Carbon-tetrachloride

A

b

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17
Q

Bourdon gauges are used for measuring
pressure (kg/cm2)
a. < atmospheric
b. > 2 (gauge)
c. < 2 (gauge)
d. > 10 (absolute)

A

b

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18
Q

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
a. light intensity
b. Current
c. flux density
d. voltage

A

a

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19
Q

A typical example of a physical system with
under damped characteristic is a
a. U-tube manometer.
b. spring loaded diaphragm valve.
c. CSTR with first order reaction.
d. thermocouple kept immersed in a liquid
filled thermowell.

A

b

20
Q

An aneroid barometer measures the
__________ pressure.
a. Atmospheric
b. Absolute
c. Vacuum
d. gage

A

b

21
Q

A bolometer is
a. used for the measurement of thermal
radiation.
b. an element which senses optical input and
delivers thermal output.
c. both (a) & (b).
d. neither (a) nor (b).

A

c

22
Q

Thermal wells are used in the temperature
measurement to
a. guard against corrosive and oxidising
action on thermocouple materials
b. reduce measuring lag.
c. increase the fidelity.
d. increase the sensitivity.

A

a

23
Q

The offset introduced by proportional controller
with gain Kcin response of first order system can be
reduced by
a. reducing value of Kc.
b. introducing integral control.
c. introducing derivative control.

A

b

24
Q

A system with a double pole at the origin is
unstable since the corresponding term in the time
domain
a. is a constant.
b. grows exponentially with time.
c. grows linearly with time.
d. decays linearly with time.

A

c

25
Q

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
a. Air
b. a metal powder or graphite
c. Oil
d. mercury

A

a

26
Q
  1. In a second order under damped system, the
    a. time required for the response of first reach its ultimate value is called the response time.
    b. overshoot (which is a measure of how much the response exceeds the ultimate value) increase with the decrease of
    damping co-efficient e.
    c. decay ratio (which is the ratio of the sizes of successive peaks) is equal to the reciprocal of overshoot.
    d. characteristics of a step response is represented by
A

b

27
Q

In an exothermic chemical reactor, the
manipulated variable is the flow rate of
a. Coolant
b. Reactants
c. Product
d. none of these

A

a

28
Q

Very low pressure is expressed in microns(μ),
which is equal to __________ mm of Hg column
(absolute) at 0°C.
a. 0.0001
b. 0.001
c. 0.01
d. 0.1

A

b

29
Q

The inverse Laplace transform of the function
is f(s) = 1/S(1+S)
a. 1 + et
b. 1 - et
c. 1 + e-t
d. 1 - e-t

A

d

30
Q

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?
a. CO2
b. N2
c. O2
d. CO

A

a

31
Q

Emf generated in a thermocouple depends on the temperature
a. of cold junction only.
b. of hot junction only.
c. difference between hot and cold junctions.
d. difference between cold junction and
atmospheric temperature.

A

c

32
Q

Working principle of mercury in glass thermometer is based on the __________ of mercury with increase in temperature.
a. increase of pressure
b. increase of thermal conductivity
c. volumetric expansion
d. differential linear expansion

A

c

33
Q

The Laplace transform of a sinusoidal function (eg;
sin at) is represented by the curve

A

a

34
Q

Number of poles in a system with transfer
function 1/s2+2s2+1
is
a. 2
b. 5
c. 3
d. 1

A

c

35
Q

Radiation thermometer can not measure the temperature
a. inside a pressure vessel.
b. of an object without coming in contact with it.
c. of liquid oxygen.
d. of moving objects at high temperature.

A

c

36
Q

Temperature measurement by optical pyrometer
is done above __________ point, which is 1063°C.
a. Antimony
b. Gold
c. Silver
d. nickel

A

b

37
Q

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?
a. CO2
b. O2
c. NO
d. NO2

A

a

38
Q

Dilatometer is used to measure
a. Stress
b. Strain
c. Deflection
d. contraction/expansion due to changes in
temperature

A

d

39
Q

Mass spectrometer is used for the composition
analysis of
a. Alloys
b. Solids
c. Isotopes
d. none of these

A

c

40
Q

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
a. 45°
b. -90°
c. -180°
d. -45°

A

d

41
Q

__________ stability method uses open loop
transfer function.
a. Nyquist
b. Mikhalov
c. Ruth
d. none of these

A

a

42
Q

A pyranometer is an instrument used for
measuring the
a. beam radiation.
b. global radiation.
c. bright sunshine period.
d. none of these.

A

b

43
Q

All the thermocouples used for temperature
measurement use dissimilar metal
a. Strips
b. Bars
c. Wires
d. beads

A

c

44
Q

The transfer function of a first order system is
a.1/Ts +1
b. 1/Ts
c. S/TS+1
d. none of these

A

a

45
Q

Composition of alloys can be determined by
a. Polarograph
b. Chromatograph
c. Refractrometer
d. none of these

A

a

46
Q

Optical activity of a solution can be determined
using a
a. Polarimeter
b. Polarograph
c. Dilatometer
d. refractrometer

A

a

47
Q

Stability of a control system containing a
transportation lag can be best analysed by
a. Routh test
b. root locus methods
c. frequency response methods
d. none of these

A

c

48
Q

Stabilising time for the controllers is the time
required for the response to reach __________
percent of its ultimate value.
a. 63.2
b. 87.5
c. 95
d. 100

A

c

49
Q
A

process ctrl inst (7 decks)

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