Process Control and Instrumentation for Chemical Engineering - Set 10 - ObjectiveBooks

Process Control and Instrumentation for Chemical Engineering - Set 10

Practice Test: Question Set - 10

1. Emf developed by a thermocouple while measuring a temperature of 800°C is about 31 mV. The type of thermocouple used is
    (A) Chromel-alumel
    (B) Iron-constantan
    (C) Platinum-platinum + rhodium
    (D) None of these

2. Feed forward controller accounts for the __________ changes.
    (A) Set point
    (B) Load
    (C) Both (a) & (b)
    (D) Neither (a) nor (b)

3. Hot wire anemometer is used for the measurement of
    (A) Flow rates of fluids
    (B) Flow rates of granular solids
    (C) Very high temperature
    (D) Thermal conductivity of gases

4. Thermal wells are used in the temperature measurement to
    (A) Guard against corrosive and oxidizing action on thermocouple materials
    (B) Reduce measuring lag
    (C) Increase the fidelity
    (D) Increase the sensitivity

5. Phase lag of the sinusoidal response of a first order system is
    (A) 120°
    (B) 30°
    (C) 180°
    (D) 90°

6. Liquid flow rate in a small channel is best measured by a/an
    (A) Weir
    (B) Pitot tube
    (C) Vane meter
    (D) Venturimeter

7. When the damping co-efficient (ξ) is unity, the system is
    (A) Overdamped
    (B) Critically damped
    (C) Underdamped
    (D) Highly fluctuating

8. A first order system with a time constant of 1 min is subjected to frequency response analysis. At an input frequency of 1 radian/min, the phase shift is
    (A) 45°
    (B) -90°
    (C) -180°
    (D) -45°

9. A system with transfer function [(2S/4S) + 1] is of ________ order.
    (A) Zero
    (B) 1st
    (C) 2nd
    (D) 3rd

10. Pick out the most suitable instrument for measuring temperature in the range of-40 to 425°C.
    (A) Mercury thermometer
    (B) Bimetallic thermometer
    (C) Radiation pyrometer
    (D) None of these

11. Flow rate measurement of hostile acids and alkalis can be most suitably done by a/an
    (A) Venturimeter
    (B) Orificemeter
    (C) Magnetic flow meter
    (D) Hot wire anemometer

12. What is the normal percentage of rhodium in platinum + rhodium element used in the thermocouple?
    (A) 0.1
    (B) 3
    (C) 13
    (D) 29

13. Platinum resistance thermometer is the international standard for temperature measurement between
    (A) Triple point of hydrogen and freezing point of antimony
    (B) 13.81°K to 903.9°K
    (C) Both (a) and (b)
    (D) Neither (a) nor (b)

14. Pick out the wrong statement.
    (A) There is no transfer lag for a single first order system
    (B) Stirred tank with a water jacket exemplifies an interacting system
    (C) Transfer lag is a characteristic of all higher order systems (other than first order systems)
    (D) Transfer lag decreases as the number of stages decreases

15. Which of the following thermocouple materials does not contain nickel?
    (A) Alumel
    (B) Chromel
    (C) Constantan
    (D) None of these

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