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Chemical Engineering :: Process Control and Instrumentation

  1. Time constant is the

  2. A.
    time taken by the controlled variable to reach 63.2% of its full change.
    B.
    same as transportation lag.
    C.
    same as dead time.
    D.
    time required by the measured variable to reach 63.2% of its ultimate change.

  3. Mercury manometer (U-tube type) exemplifies a __________ order system.

  4. A.
    zero
    B.
    first
    C.
    second
    D.
    third

  5. Emf developed by a thermocouple while measuring a temperature of 400°C is 22 mV. The type of thermocouple used is

  6. A.
    chromel-alumel
    B.
    iron-constantan
    C.
    platinum-rhodium
    D.
    platinum-platinum+rhyodium

  7. Bode stability method uses __________ loop transfer function.

  8. A.
    open
    B.
    closed
    C.
    either (a) or (b)
    D.
    neither (a) nor (b)

  9. Working principle of bimetallic thermometers is difference in linear co-efficient of thermal expansion of two strips of different metals welded together. Which of the following has the maximum thermal co-efficient of linear expansion?

  10. A.
    Nickel
    B.
    Brass
    C.
    Chromel
    D.
    Invar

  11. Which of the following is not a second order instrument ?

  12. A.
    Mercury in glass thermometer with covering.
    B.
    Bare mercury in glass thermometer.
    C.
    Pressure gauge with one bellow, two tubes and a tank.
    D.
    None of these.

  13. Small furnace draught is accurately measured by an inclined tube manometer, in which the manometric liquid used most commonly is

  14. A.
    water
    B.
    carbon tetrachloride
    C.
    paraffin
    D.
    ethylene glycol

  15. Specific conductance is defined as the reciprocal of resistance in ohms of 1c.c. of liquid at a specified temperature. Its value for distilled water is about __________ micro mho/cm3.

  16. A.
    50
    B.
    100
    C.
    10
    D.
    1

  17. A simple pitot tube measures the

  18. A.
    average velocity
    B.
    maximum velocity
    C.
    point velocity
    D.
    static pressure

  19. For a feed back control system to be stable, the

  20. A.
    roots of the characteristic equation should be real.
    B.
    poles of the closed loop transfer function should lie in the left half of the complex plane.
    C.
    Bode plots of the corresponding open loop transfer function should monotoni-cally decrease.
    D.
    poles of the closed loop transfer function should lie in the right half of the complex plane.