Process Control and Instrumentation pdf MCQ Practice - Set 03 - ObjectiveBooks

Process Control and Instrumentation pdf MCQ Practice - Set 03

Practice Test: Question Set - 03

1. 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:
Process Control - Set 03, Question No. 01
    (A) Q0(T0 - T) = Ac . h (dT/dt)
    (B) Q0T0 - QT = Ac . h (dT/dt)
    (C) Q(T0 - T) = Ac . h (dT/dt)
    (D) Q(T0 - T) = Ac . (dTH/dt)

2. The root locus plot of the roots of the characteristics equation of a closed loop system having the open loop transfer function K (s + 1)/[2 (2s + 1) (3s + 1)]  will have a definite number of loci for variation of K from 0 to ∞. The number of loci is
    (A) 1
    (B) 2
    (C) 3
    (D) 4

3. Nitrogen gas constant volume thermometer is suitable for measuring a temperature of _________ °C.
    (A) 0-100
    (B) < 0
    (C) > 100
    (D) > 50

4. 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

5. Mercury thermometer can be used to measure the temperature upto _________ °C.
    (A) 100
    (B) 250
    (C) 350
    (D) 750

6. Working principle of mercury in glass thermometer is
    (A) Volumetric expansion
    (B) Pressure rise with temperature
    (C) Linear expansion
    (D) None of these

7. In a closed loop system, the process to be controlled is an integrating process with transfer function 1/2s. The controller proposed to be used in an integral controller with transfer function 1/T1s. When a step change in set point is applied to such a closed loop system, the controlled variable will exhibit
    (A) Overdamped response
    (B) Underdamped response
    (C) Undamped response
    (D) Unstable response

8. 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

9. 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

10. Temperature of _________ cannot be measured by an optical or radiation pyrometer.
    (A) Hot blast (air) from stoves
    (B) Molten slag flowing out of blast furnace
    (C) Combustion space in boilers
    (D) Rotary limestone calcination kiln

11. "A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency." This is _________ criterion.
    (A) Bode stability
    (B) Nyquist
    (C) Routh stability
    (D) None of these

12. Platinum resistance thermometer can be used upto 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

13. 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
    (C) Decay ratio (which is the ratio of the sizes of successive peaks) is equal to the reciprocal of overshoot
    (D) None of these

14. Which of the following thermocouples has the least temperature measurement range?
    (A) Copper-constantan
    (B) Chromel-alumel
    (C) Platinum-platinum/rhodium
    (D) Iron-constantan

15. Which is the symbol for ‘pneumatic control valve’?
Process Control - Set 03, Question No. 15

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