Instrumentation and Process Control Workbook Solutions - Set 20 - ObjectiveBooks

Instrumentation and Process Control Workbook Solutions - Set 20

Practice Test: Question Set - 20

1. Emf developed by a thermocouple, while measuring a temperature of 600°C is about 5.5 mV. The type of thermocouple used is
    (A) Chromel-alumel
    (B) Iron-constantan
    (C) Platinum-platinum + rhodium
    (D) Either (a), (b) or (c)

2. _________ is the static characteristics of an instrument.
    (A) Response
    (B) Tine lag
    (C) Drift
    (D) Dynamic error

3. Pressure of 0.0001 absolute psi can be measured by _________ gauge.
    (A) Mcleod
    (B) Pirani
    (C) Thermocouple
    (D) None of these

4. Pick out the wrong statement.
    (A) O2, NO and NO2 exhibit paramagnetic properties as a result of unpaired electrons
    (B) CO2 is the strongest paramagnetic gas
    (C) Paramagnetic susceptibility of gases decreases with temperature
    (D) Paramagnetic susceptibility of gases permits the measurement of their concentration

5. Process degree of freedom indicates __________ number of controllers to be used.
    (A) The maximum
    (B) The minimum
    (C) Both maximum and the minimum
    (D) Nothing about the

6. The unit step response of the transfer function (2s - 1)/[(3s + 1) (4s + 1)] reaches its final steady state asymptotically after
    (A) A monotonic increase
    (B) A monotonic decrease
    (C) Initially increasing and then decreasing
    (D) Increasing decreasing and then increasing

7. Thermal conductivity measurement com-prises the working principle of a
    (A) CO2 analyzer
    (B) Polarimeter
    (C) Spectrometer
    (D) Chromatograph

8. Thermal wells used in temperature measurements should have
    (A) Very thick walls
    (B) Low emissivity
    (C) Polished surface
    (D) High transmissivity of radiation

9. Which of the following is a 'contact' pyrometer?
    (A) Resistance pyrometer
    (B) Optical pyrometer
    (C) Radiation pyrometer
    (D) Infra red pyrometer

10. A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if
    (A) Kc is reduced
    (B) Kc is increased
    (C) Integral control action is introduced
    (D) Derivative control action is introduced

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

12. On-off controllers are normally used for
    (A) Low loads
    (B) Temperature changes
    (C) Flow rate changes
    (D) None of these

13. The _________ of a vapor pressure thermometer is a functioning element.
    (A) Pointer
    (B) Bourdon tube
    (C) Bulb
    (D) None of these

14. A pyrheliometer is an instrument used for measuring the
    (A) Bright sunshine period
    (B) Beam radiation
    (C) Diffuse radiation
    (D) None of these

15. Pirani gauge is used for the measurement of
    (A) Very high pressure
    (B) High vacuum
    (C) Liquid level under pressure
    (D) Liquid level at atmospheric pressure

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