Recent questions in Instrumentation and Process Control

In the P&ID shown below, which one of the following is the function of PAH in the process?to maintain a constant pressure in the vessel by throttling the pump outletto al...

A process exhibits an inverse response to a step input. Which of the following statements is/are necessarily TRUE about the process?Its transfer function has a positive z...

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 ...

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 cl...

​​​​The vortex shedding meter is primarily used for measuringFluid Flow RateLiquid LevelFluid TemperatureFluid Pressure

​​​​Choose the transfer function that best fits the output response to a unit step input change shown in the figure $\frac{(\alpha s+1) e^{-\theta s}}{\left(\tau_{1} s+1\...

​​​​The first-order irreversible liquid phase reaction $A \rightarrow B$ occurs inside a constant volume $(V)$ isothermal CSTR with the initial steady state conditions sh...

Consider the block diagram in the figure with control input $u$, disturbance $d$ and output $y$. For the feedforward controller, the ordered pair $(K, \alpha / \beta)$ is...

​​​​​Consider the control structure for the overhead section of a distillation column shown in the figure. The composition controller (CC) controls the heavy key impurity...

​​​​​​For the block diagram shown in the figure, the correct expression for the transfer function $G_{d}=\frac{y_{1}(s)}{d(s)}$ is$\frac{-G_{p 1} G_{c 2}}{\left(1+G_{c 1}...

Consider the surge drum in the figure. Initially the system is at steady-state with a hold-up $\bar{V}=5 \mathrm{~m}^{3}$, which is $50 \%$ of full tank capacity, $V_{f u...

A $\text{PD}$ controller with transfer function $G_{c}$ is used to stabilize an open-loop unstable process with transfer function $G_{p}$, where\[G_{c}=K_{c} \frac{\tau_{...

A liquid surge tank has $F_{\text {in }}$ and $F_{\text {out }}$ as the inlet and outlet flow rates respectively, as shown in the figure below. $F_{\text {out }}$ is prop...

A cascade control strategy is shown in the figure below. The transfer function between the output $(y)$ and the secondary disturbance $\left(d_2\right)$ is defined as$$G_...

Level $(h)$ in a steam boiler is controlled by manipulating the flow rate $(F)$ of the make-up (fresh) water using a proportional (P) controller. The transfer function be...

The outlet concentration $C_A$ of a plug flow reactor $\text{(PFR)}$ is controlled by manipulating the inlet concentration $C_{A 0}$. The following transfer function desc...

The transfer function of a measuring instrument is$$G_m(s)=\frac{1.05}{2 s+1} \exp (-s) .$$At time $t=0$, a step change of $+1$ unit is introduced in the input of this in...

A control system on the jacket side of a reactor is shown in the figure. Pressurized water flows through the jacket to cool the reactor. The heated water flashes in the b...

Liquid flowing through a heat exchanger $\text{(HX)}$ is heated. A bypass stream is provided to control the temperature of the heated exit stream. From the given plumbing...

The appropriate feedforward compensator, $G_{ff}$, in the shown block diagram is$G_{ff} = \dfrac{2}{3}\dfrac{\left ( 8s + 1\right )}{\left ( 5s + 1\right )}$$G_{ff} = -\d...

Choose the option that correctly pairs the given measurement devices with the quantities they measure.$$\begin{array}{ccc} \hline\text{S No} & \text{Measurement Device} &...

A process described by the transfer function $$G_{P}\left ( s \right ) = \frac{\left ( 10s +1 \right )}{5s + 1}$$ is forced by a unit step input at time $t = 0$. The outp...

In the block diagram shown in the figure, the transfer function $G = \dfrac{K}{\left ( \tau s + 1 \right )}$ with $K 0$ and $\tau 0$. The maximum value of $K$ below whi...

Consider the tank level control system shown in the figure, where the cross-section area of the tank is $A$. Assume perfect flow controllers $\text{(FC)}$. The level cont...

Consider a single-input-single-output $\text{(SISO)}$ system with the transfer function $$G_{P}\left ( s \right ) =\frac{2\left ( s + 1 \right )}{\left ( \dfrac{1}{2} s +...

Which of the following is $\text{NOT}$ a standard to transmit measurement and control signals?$4-20 \: \text{mA}$$3-15 \text{ psig}$$0-100\: \%$$1-5 \text{ VDC}$

A feedforward controller can be used only ifthe disturbance variable can be measuredthe disturbance variable can be manipulatedthe disturbance variable can be ignoredregu...

The inherent characteristics of the three control valves $P$, $Q$ and $R$ are shown in the figure.The $\text{CORRECT}$ option(s) is/are$P$ is a quick opening valve$Q$ is ...

Which of these symbols can be found in piping and instrumentation diagrams?$(Q)$ and $(S)$ only$(P)$, $(Q)$ and $(R)$ only$(P)$, $(R)$ and $(S)$ only$(P)$, $(Q)$, $(R)$ a...

It is required to control the volume of the contents in the jacketed reactor shown in the figure.Which one of the following schemes can be used for feedback control?Measu...

Which of the following is $\text{NOT}$ a necessary condition for a process under closed-loop control to be stable?Dead-time term(s) must be absent in the open-loop transf...

A system has a transfer function $G(s)= \dfrac{3e^{-4s}}{12s+1}$. When a step change of magnitude $M$ is given to the system input, the final value of the system output i...

A person has a transfer function $G(s)= \dfrac{Y(s)}{X(s)} = \dfrac{20}{90000s^2+240s+1}$. Initially the process is at steady state with $x(t=0)=0.4$ and $y(t=0)=100$. If...

Consider the following closed loop system with $G_p$ and $G_c$ as the transfer functions of the process and the controller, respectively.For a unit step change in the set...

Flow of water thorough an equal percentage valve is $900 \text{ litre } h^{-1}$ at $30 \%$ opening, and $1080 \text{ litre } h^{-1}$ at $35 \%$ opening. Assume that the p...

Consider the following closed loop system.$G_c, G_f$ , and $G_p$ are the transfer functions of the controller, the final control element and the process, respectively. $Y...

Hot-wire anemometer is used for the measurement ofcompositionflowpressuretemperature

A thermocouple senses temperature based on theNernst Effect Maxwell Effect Seebeck EffectPeltier Effect