GATE CH topic:instrumentation-and-process-control PYQs & Answers — Page 5

Questions 41–50 of 54. Imported answers require independent review unless marked reviewed.

The liquid flow rate through an equal percentage control valve, when fully open, is 150 gal/min and the corresponding pressure drop is 50 psi. If the specific gravity of the liquid is 0.8, then the valve coefficient,

(in gal/(min psi

)) is ______ (rounded off to two decimal places).

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Consider two non-interacting tanks-in-series as shown in figure. Water enters TANK 1 at

/s and drains down to TANK 2 by gravity at a rate

(cm

/s). Similarly, water drains from TANK 2 by gravity at a rate

(cm

/s) where

and

represent levels of TANK 1 and TANK 2, respectively (see figure). Drain valve constant

/s and cross-sectional areas of the two tanks are

. At steady state operation, the water inlet flow rate is

/s. The transfer function relating the deviation variables

(cm) to flow rate

(cm

/s) is,

Diagram for Chemical Engineering question 30

Your answerChoose one option.

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Choose the option that correctly matches the step response curves on the left with the appropriate transfer functions on the right. The step input change occurs at time

Diagram for Chemical Engineering question 31

Your answerChoose one option.

P – II, Q – IV; R – II, S – I

P – III, Q – I; R – IV, S – II

P – IV, Q – III; R – II, S – I

P – III, Q – II; R – IV, S – I

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For the closed loop system shown in figure,

Diagram for Chemical Engineering question 49

the phase margin (in degrees) is __________ (rounded off to one decimal place).

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A first-order process having a transfer function, Gₚ = 2/(7s + 1) is controlled by a proportional controller with gain of 3.2. The process time constant is in minutes. Addition of the integral control action with an integral time constant of 5 minutes leads to increase in

Your answerChoose one option.

offset

speed of response

order of the closed loop system

proportional band

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The decay ratio for a system having complex conjugate poles as (−1/10 + j 2/15) and (−1/10 − j 2/15) is

Your answerChoose one option.

7×10⁻¹

8×10⁻²

9×10⁻³

10×10⁻⁴

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Match the items in Column A with the items in Column B

Column A	Column B
(P) Pure dead-time	(I)
(Q) Pure capacitive	(II) with
(R) Inverse response	(III)
(S) First-order process with unit gain	(IV)

Here,

denotes the phase shift,

and

the process gains,

the time constant, and AR the amplitude ratio.

Your answerChoose one option.

P-II, Q-III, R-IV, S-I

P-II, Q-II, R-IV, S-I

P-I, Q-IV, R-II, S-III

P-IV, Q-I, R-II, S-III

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Consider the following transfer function:

where, the natural period of oscillation is in min. The amplitude ratio at a frequency of 0.5 rad/min is ____________ (rounded off to second decimal place).

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For a closed-loop system, consider the following transfer functions: process

, controller

, measuring device

, and final control element

The offset in the closed loop response due to a unit step change introduced in the set point of the output variable is ________.

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Match the variables in Group-1 with the instruments in Group-2.

Group-1 P) Temperature Q) Liquid level R) Vacuum S) Concentration

Group-2 I) Capacitance probe II) McLeod gauge III) Chromatograph IV) Thermistor

Choose the correct set of combinations.

Your answerChoose one option.

P-IV, Q-III, R-II, S-I

P-I, Q-II, R-IV, S-III

P-IV, Q-I, R-II, S-III

P-III, Q-II, R-I, S-IV

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GATE CH topic:instrumentation-and-process-control PYQs

Question 24

Question 30

Question 31

Question 49

Question 18

Question 31

Question 32

Question 44

Question 45

Question 20