Process Control and Instrumentation problems
- 1. Which of the following is a desirable characteristic of an instrument?
Options- A. High drift
- B. High fidelity
- C. High measuring lag
- D. Poor reproducibility Discuss
Correct Answer: High fidelity
- 2. Zirconia probe is used for the continuous measurment of __________ flue gases going out of the furnace.
Options- A. oxygen in
- B. carbon dioxide in
- C. carbon monoxide in
- D. temperature of Discuss
Correct Answer: oxygen in
- 3. Emf developed by a thermocouple, while measuring a temperature of 600°C is about 5.5 mV. The type of thermocouple used is
Options- A. chromel-alumel
- B. iron-constantan
- C. platinum-platinum+rhodium
- D. either (a), (b) or (c) Discuss
Correct Answer: platinum-platinum+rhodium
- 4. Instrumentation in a plant offers the advantage of
Options- A. greater safety of operation
- B. better quality of product
- C. greater operation economy
- D. all (a), (b) and (c) Discuss
Correct Answer: all (a), (b) and (c)
- 5. A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if
Options- A. Kc is reduced.
- B. Kc is increased.
- C. integral control action is introduced.
- D. derivative control action is introduced. Discuss
Correct Answer: Kc is increased.
- 6. A negative gain margin expressed in decibels means a/an __________ system.
Options- A. stable
- B. unstable
- C. critically damped
- D. none of these Discuss
Correct Answer: unstable
- 7. Which of the following measurements can be made by the measurement of emf?
Options- A. pH value
- B. Degree of hydrolysis
- C. Composition of complex ions
- D. All (a), (b) & (c) Discuss
Correct Answer: All (a), (b) & (c)
- 8. Smoke density of the flue gas going out of the chimney is measured by a
Options- A. polarograph
- B. thermal conductivity meter
- C. photo electric cell
- D. chromatograph Discuss
Correct Answer: photo electric cell
- 9. The transfer function for a PID controller is (where, ? i is the integral (reset) time and ?D is the derivative time.)
Options- A. Kc(1 + ?is + ?D ). s
- B.
- C.
- D.
Discuss
Correct Answer:
- 10. The __________ of a vapor pressure thermometer is a secondary element.
Options- A. pointer
- B. Bourdon tube
- C. bulb
- D. none ofthese Discuss
Correct Answer: Bourdon tube
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