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process ctrl inst > section 6 > Flashcards

section 6 Flashcards

1
Q

Pyrometry refers to the measurement of
temperature
a. with the mercurial thermometer up to 350°C.
b. Directly.
c. which is of higher magnitude.
d. all (a), (b) & (c).

A

C

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2
Q

Photoelectric pyrometers are suitable in the
temperature range of __________ °C.
a. 400-1600
b. 800-1600
c. 800-2500
d. 400-1000

A

B

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3
Q

Non-metallic diaphragm used as pressure sensor in instruments is generally made of
a. Teflon
b. synthetic rubber
c. Bakelite
d. thick paper

A

B

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4
Q
  1. Response of a linear control system for a change
    in set point is called
    a. frequency response
    b. transient response
    c. servo problem
    d. regulator problem
A

C

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5
Q

Hot wire anemometer is used for the
measurement of
a. flow rates of fluids.
b. flow rates of granular solids.
c. very high temperature.
d. thermal conductivity of gases.

A

A

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6
Q

Which of the following thermocouples has the
widest temperature measurement range?
a. Iron-constantan
b. Chromel-alumel
c. Copper-constantan
d. Platinum-platinum/rhodium

A

D

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7
Q

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

a. air to open valve with the controller direct
acting.
b. air to close valve with the controller
indirect acting.
c. air to open valve with the controller indirect
acting.
d. air to close valve with the controller direct acting.

A

C

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8
Q
  1. Bourdon tube is never made of
    a. phosphor bronze
    b. monel metal
    c. stainless steel
    d. cast iron
A

D

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9
Q

“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
a. pH meter
b. Polarimeter
c. Chromatograph
d. polarograph

A

A

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10
Q

Pick out the symbol for “locally mounted
instrument” in instrumentation diagram.
A. O

A

A

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11
Q

Which of the following statement about the above
control system is wrong?
a. The transfer functions of the measuring
element and the process is represent by H
and G2 respectively
b. The overall transfer function for the change
in load (X = 0) is given by YY
XX1
= GGCC.GG1.GG2
1+GGcc.GG1.GG2.HH
c. The overall transfer function for the change
in set point (X1 = 0) is given by YY
XX1
=

GGCC.GG1.GG2
1+GGcc.GG1.GG2.HH
d. Manipulated variable is represented by C.

A

D

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12
Q
  1. 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.

a. Tank 1
b. Tank 2
c. Tank 3
d. Tank 4

A

C

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13
Q

The term analogous to voltage in a single tank
system is the
a. heat content of the system.
b. liquid volume in the tank.
c. flow rate.
d. level of liquid.

A

D

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14
Q

In a shell and tube heat exchanger, the outlet
temperature of heating/cooling fluid is the
__________ variable.
a. Load
b. Manipulated
c. Controlled
d. none of these

A

C

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15
Q
  1. Mcleoid gauge is used to measure the
    a. point velocity
    b. flow rate
    c. Vacuum
    d. pressure
A

C

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16
Q

What is the Laplace transform of impulse input
having magnitude ‘X’?
a. X
b. X2
c. 1/X
d. 1

A

D

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17
Q

Thermocouple is suitable for measuring
a. liquid temperatures only.
b. very high temperatures only.
c. very low temperatures only.
d. both high and low temperatures.

A

D

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18
Q

Bimetal strips are not used in
a. bimetallic thermometers.
b. Thermocouples.
c. Thermostats.
d. relays for opening & closing of electrical
circuits.

A

B

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19
Q

When the damping co-efficient (ξ) is unity, the
system is
a. Overdamped.
b. Critically damped.
c. Underdamped.
d. Highly fluctuating.

A

B

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20
Q

Nickel percentage in invar which is an iron-
nickel alloy, and is used as a thermocouple material

is
a. 12
b. 36
c. 54
d. 68

A

B

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21
Q

Which is the symbol for “pneumatic control
valve”?

A

A

22
Q

Silver point temperature is __________ °C.
a. 760.5
b. 860.5
c. 960.5
d. 1060.5

A

C

23
Q

A non-linear system will have __________
steady state values.
a. One
b. more than one
c. Two
d. three

A

B

24
Q

Which of the following is not a variable area
flow meter?
a. Piston type meter
b. Rotameter
c. Magnetic flow meter
d. Orifice and tapered plug meter

A

C

25
Q

With increase in temperature, the electrical
conductivity of the platinum used in the resistance
thermometer
a. Increases
b. Decreases
c. remains constant
d. increases exponentially

A

B

26
Q

Sub-zero temperature (< 0°C) can be measured
by a constant volume gas thermometer employing
a. Helium
b. Nitrogen
c. Hydrogen
d. none of these

A

A

27
Q

__________ is an example of distributed
parameter system
a. Tubular reactor
b. CSTR
c. On-off controller
d. none of these

A

A

28
Q

Which of the following is not classified as a
thermo electric pyrometer?
a. Resistance thermometer.
b. Thermocouple.
c. Optical pyrometer (disappearing filament
type)
d. Radiation pyrometer

A

C

29
Q

Maximum differential pressure in liquid
manometer is __________ psi.
a. 20
b. 30
c. 40
d. 50

A

B

30
Q

Phase margin is equal to
a. 180° - phase lag
b. phase lag - 180°
c. phase lag + 180°
d. phase lag + 90°

A

A

31
Q
  1. In a feed-back control system G and H denote
    open loop and close loop transfer functions
    respectively. The output-input relationship is
    a.G/1+H
    b. HH/1+G
    c.G/H
    d. H/G
A

B

32
Q

Flow rate measurement of hostile acids and
alkalis can be most suitably done by a/an
a. Venturimeter
b. Orificemeter
c. magnetic flow meter
d. hot wire anemometer

A

C

33
Q

Compositional analysis of flue gas coming out
of a furnace in respect of O2 and CO2% can be
continuously done by a/an
a. orsat apparatus
b. thermal conductivity cell
c. zirconia probe
d. chromatograph

A

B

34
Q

Thermistors which have a very high temperature
co-efficient of resistivity belong to the class of solid
called
a. Dielectrics
b. Insulators
c. semi conductors
d. conductors

A

C

35
Q

The pressure sensing element of elastic type
pressure gauge is never made in the form of a
a. Bellow
b. Diaphragm
c. Strip
d. Bourdon tube

A

C

36
Q
  1. Liquid flow rate in an open channel can not be
    measured by a/an
    a. orifice meter
    b. cipolletti weir
    c. rectangular weir
    d. V-notch
A

A

37
Q

The unit of ‘time constant’ of a system is the
same as that of
a. Velocity
b. Time
c. (time)-1
d. none of these

A

B

38
Q

Which of the following filled system expansion
thermometers has the lowest positive temperature
measurement capability?
a. Mercury in glass thermometer.
b. Alcohol in glass thermometer.
c. Fused metal (Na or K) in steel
thermometer.
d. Nitrogen in steel thermometer.

A

B

39
Q

Liquid column manometers are used for
measuring the pressure __________ kgf/cm2
a. > 2(gage)
b. < 3 (gage)
c. < 10 (gage)
d. < atmospheric

A

B

40
Q
  1. Cascade control means
    a. feed forward control.
    b. more than one feed-back loop.
    c. on-off control.
    d. one feed-back loop.
A

B

41
Q

The level of a liquid under pressure can be
determined using
a. bubbler system
b. differential pressure manometer
c. diaphragm box system
d. air-trap system

A

B

42
Q

Temperature measurement range of iron-
constantan thermocouple is 0 to 870°C. It can be

used to measure subzero temperature, because at
lower temperature
a. emf produced is very low of the order of
microvolt.
b. embrittlement of iron occurs.
c. rusting of iron takes place.
d. both (b) and (c).

A

D

43
Q

Which of the following is never used as an
element of industrial resistance thermometer?
a. Lead
b. Nickel
c. Copper
d. 30% iron + 70% nickel

A

A

44
Q

Which of the following shows maximum dip
effect (indicating reverse direction of temperature
change)?
a. Mercury thermometer
b. Radiation pyrometer
c. Bimetallic thermometer
d. Thermocouple

A

A

45
Q

A stable system is the one
a. for which the output response is bounded
for all bounded input.
b. which exhibits an unbounded response to a
bounded input
c. which satisfies the conditions for a servo
problem.
d. none of these.

A

A

46
Q

The Laplace transform of exp(at), where a > 0,
is defined only for the Laplace parameter, s > a
since
a. the function is exponential.
b. the Laplace transform of integral of exp(at)
has finite values only for s > a.
c. the Laplace transform integral of exp(at)
has initial values only for s > a.
d. the function exp(at) is piece-wise
continuous only for s > a.

A

B

47
Q

Meleoid gauge measures the __________
pressure.
a. Positive
b. Sub-atmospheric
c. very high
d. atmospheric

A

B

48
Q

Which of the following thermocouples is
capable of measuring a temperature of -50°C?
a. Platinum - platinum + rhodium
b. Chromel - alumel
c. Iron-constantan
d. Copper - constantan

A

A

49
Q

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).
a. w = 1/sqrt14, Kc = 45/7sqrt14
b. w = sqrt(7/6), Kc = 46/3
c. w = 1, Kc = 13
d. w = sqrt(7⁄8), Kc = 45/4

A

B

50
Q

Platinum resistance thermometer can be used up
to antimony point which is __________ °C, and is
the temperature of equilibrium between solid
antimony & liquid antimony at normal atmospheric
pressure.
a. 961.93
b. 630.74
c. 1064.43
d. 1261.93

A

B

51
Q
A

process ctrl inst (7 decks)

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