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Home Chemical Engineering Process Control and Instrumentation Comments

  • Question
  • 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.

  • Correct Answer
  • Kc is increased. 


  • Process Control and Instrumentation problems


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    • 1. 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
    • 2. 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
    • 3. 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
    • 4. 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
    • 5. Thermistor, which has high temperature co-efficient of resistivity, is used as the sensing element in resistance thermometer. It is a/an

    • Options
    • A. insulator
    • B. conductor
    • C. solid semi-conductor
    • D. liquid semi-conductor
    • Discuss
    • 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
    • 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
    • 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
    • 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
    • 10. The __________ of a vapor pressure thermometer is a secondary element.

    • Options
    • A. pointer
    • B. Bourdon tube
    • C. bulb
    • D. none ofthese
    • Discuss


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