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Instrumentation and Process Control

30 Questions
GATE→2026→Instrumentation and Process Control→Instrumentation and Process Control
Q1
MCQ[1 Mark]
In the P&ID shown below, which one of the following is the function of PAH in the process?
Figure for Question 1
GATE→2026→Instrumentation and Process Control→Instrumentation and Process Control
Q2
MSQ[1 Mark]
A process exhibits an inverse response to a step input. Which of the following statements is/are necessarily TRUE about the process?
GATE→2026→Instrumentation and Process Control→Instrumentation and Process Control
Q3
MCQ[2 Marks]
A control valve with hyperbolic characteristics has a turndown ratio (ratio of maximum flow to minimum controllable flow) of 50. The flow rate through the valve at 70% open is 5 m3s−15~\text{m}^3\text{s}^{-1}. Assuming constant fluid density and pressure drop across the valve, which one of the following is the flow rate (in m3s−1\text{m}^3\text{s}^{-1}) through the valve at 30% open?
GATE→2026→Instrumentation and Process Control→Instrumentation and Process Control
Q4
MCQ[2 Marks]
Consider three identical non-interacting first order processes in series, each having unit gain and a time constant of 2 min. Tuning of proportional controller using closed loop Ziegler-Nichols technique is considered. Which one of the following is the ultimate period of sustained cycling (in min per cycle)?
GATE→2026→Instrumentation and Process Control→Instrumentation and Process Control
Q5
NAT[2 Marks]
A thermometer initially at a steady temperature of 30 ∘C30~^\circ\text{C} is inserted in a water bath maintained at 90 ∘C90~^\circ\text{C}. The initial rate of temperature rise of the thermometer is 2 ∘C s−12~^\circ\text{C s}^{-1}. Assuming first order behavior, the thermometer reading (in ∘C^\circ\text{C}) after one minute is ______ (rounded off to one decimal place).
GATE→2025→Instrumentation and Process Control→Instrumentation and Process Control
Q6
MCQ[1 Mark]
The vortex shedding meter is primarily used for measuring
GATE→2025→Instrumentation and Process Control→Instrumentation and Process Control
Q7
MCQ[1 Mark]
Choose the transfer function that best fits the output response to a unit step input change shown in the figure
Figure for Question 7
GATE→2025→Instrumentation and Process Control→Instrumentation and Process Control
Q8
NAT[1 Mark]
The residence-time distribution (RTD) function of a reactor (in min−1^{-1}) is given. The mean residence time of the reactor is ______ min (rounded off to 2 decimal places).
GATE→2025→Instrumentation and Process Control→Instrumentation and Process Control
Q9
MCQ[2 Marks]
The first-order irreversible liquid phase reaction A→BA \to B occurs inside a constant volume (VV) isothermal CSTR... The gain, in kmol/m3m3/h\frac{\text{kmol/m}^3}{\text{m}^3\text{/h}}, of the transfer function is
Figure for Question 9
GATE→2025→Instrumentation and Process Control→Instrumentation and Process Control
Q10
NAT[2 Marks]
Consider a process with transfer function Gp=2e−s(5s+1)2G_p = \frac{2e^{-s}}{(5s+1)^2}. A FOPDT model is to be fitted using maximum slope method. The value of τmθm\frac{\tau_m}{\theta_m} is ______ (rounded off to 2 decimal places).
GATE→2025→Instrumentation and Process Control→Instrumentation and Process Control
Q11
NAT[2 Marks]
The block diagram of a series cascade control system is shown. For τI=8\tau_I = 8 min and Kcs=1K_c^s = 1, the maximum value of KcmK_c^m below which stability is maintained is ______ (rounded off to the nearest integer).
GATE→2024→Instrumentation and Process Control→Instrumentation and Process Control
Q12
MCQ[1 Mark]
For the feedforward controller block diagram, the ordered pair (K,α/β)(K, \alpha/\beta) is
Figure for Question 12
GATE→2024→Instrumentation and Process Control→Instrumentation and Process Control
Q13
MCQ[1 Mark]
The sign of the controller gain for the pressure controller (PC) and composition controller (CC) are, respectively,
Figure for Question 13
GATE→2024→Instrumentation and Process Control→Instrumentation and Process Control
Q14
MCQ[2 Marks]
For the block diagram shown in the figure, correct expression for transfer function Gd=y1(s)/d(s)G_d = y_1(s)/d(s) is.
Figure for Question 14
GATE→2024→Instrumentation and Process Control→Instrumentation and Process Control
Q15
NAT[2 Marks]
Surge drum hold-up control with P-only controller. Step increase in feed from 11 to 2 m3h−12 \text{ m}^3\text{h}^{-1}. Minimum controller gain KcminK_c^{min} ensuring hold-up never exceeds VhighV_{high} is h−1^{-1}.
Figure for Question 15
GATE→2023→Instrumentation and Process Control→Instrumentation and Process Control
Q16
MCQ[1 Mark]
Which one of the following quantities of a flowing fluid is measured using a rotameter?
GATE→2023→Instrumentation and Process Control→Instrumentation and Process Control
Q17
MCQ[1 Mark]
Liquid surge tank parameters given. Time constant (in seconds) is
Figure for Question 17
GATE→2023→Instrumentation and Process Control→Instrumentation and Process Control
Q18
MCQ[1 Mark]
An isothermal jacketed CSTR shown in figure... Which statement is the CORRECT action to increase TT?
Figure for Question 18
GATE→2023→Instrumentation and Process Control→Instrumentation and Process Control
Q19
MCQ[2 Marks]
For the cascade control strategy shown, the transfer function Gd2(s)=y(s)d2(s)G_{d2}(s) = \frac{y(s)}{d_2(s)} is
Figure for Question 19
GATE→2023→Instrumentation and Process Control→Instrumentation and Process Control
Q20
MCQ[2 Marks]
Level control transfer function given. Correct controller gain for decaying oscillations under servo mode is
GATE→2023→Instrumentation and Process Control→Instrumentation and Process Control
Q21
NAT[2 Marks]
PFR dynamics transfer function given with V=1V=1, F=0.1F=0.1, k=0.5k=0.5. Ultimate gain for proportional controller is.
GATE→2023→Instrumentation and Process Control→Instrumentation and Process Control
Q22
NAT[2 Marks]
Measuring instrument transfer function given. Time taken to show an increase of 1 unit in output for +1 step change is.
GATE→2022→Instrumentation and Process Control→Instrumentation and Process Control
Q23
MCQ[1 Mark]
Jacketed reactor control system diagram. Select the option that correctly specifies the action (direct/reverse) of controllers PC, LC, TC.
Figure for Question 23
GATE→2022→Instrumentation and Process Control→Instrumentation and Process Control
Q24
MCQ[1 Mark]
Liquid heated in HX with bypass stream plumbing options. Most effective temperature control configuration avoiding vaporization is
Figure for Question 24
GATE→2022→Instrumentation and Process Control→Instrumentation and Process Control
Q25
MCQ[1 Mark]
Appropriate feedforward compensator GffG_{ff} in the block diagram is
Figure for Question 25
GATE→2022→Instrumentation and Process Control→Instrumentation and Process Control
Q26
MCQ[1 Mark]
Choose option that correctly pairs measurement devices with quantities they measure.
GATE→2022→Instrumentation and Process Control→Instrumentation and Process Control
Q27
NAT[1 Mark]
Process transfer function Gp(s)=10s+15s+1G_p(s) = \frac{10s+1}{5s+1} forced by unit step input at t=0t=0. Output value immediately after step input (t=0+t=0^+) is.
GATE→2022→Instrumentation and Process Control→Instrumentation and Process Control
Q28
NAT[2 Marks]
Feedback control loop block diagram. Maximum value of KK for system stability is.
Figure for Question 28
GATE→2022→Instrumentation and Process Control→Instrumentation and Process Control
Q29
NAT[2 Marks]
Tank level control system with PI controller tuned for critical damping. Value of KcτIA\frac{K_c \tau_I}{A} is.
Figure for Question 29
GATE→2022→Instrumentation and Process Control→Instrumentation and Process Control
Q30
NAT[2 Marks]
SISO system transfer function given, forced by unit step input. Time at which output response reaches maximum is minutes.