chemical engineering process control and instrumentation MCQs – Page 8

Practise multiple-choice questions from chemical engineering process control and instrumentation for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering process control and instrumentation Mcqs
141. Which of the following is an undesirable dynamic characteristic of an instrument ?
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A. Static error

B. Dead zone

C. Time lag

D. Reproducibility

142. The pressure sensing element of elastic type pressure gauge is never made in the form of a_________________?
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A. Diaphragm

B. Bellow

C. Strip

D. Bourdon tube

143. Which of the following relates the emf. generated in a single homogeneous wire to the temperature difference ?
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A. Seebeck effect

B. Peltier effect

C. None of these

D. Thomson effect
144. The function of a transducer is to _______________ ?
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A. Convert the primary signal into a more useful quantity, usually an electric impulse

B. Modify the input signal

C. Amplify the input signal

D. Codify/decodify the input signal

145. Operating range of a temperature measuring instrument is 800 to 1600C. It could be a/an _____________ pyrometer?
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A. Photoelectric

B. None of these

C. Optical

D. Radiation

146. Ordinary mercury in glass thermometer is used for measuring temperature upto 120C. However, for measuring higher temperature upto __________ C, thermometer is made by filling nitrogen under pressure above the mercury, which stops the evaporation of mercury and reduces the chance of broken thread of mercury?
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A. 250

B. 700

C. 550

D. 350

147. Stability of a control system containing a transportation lag can be best analysed by_______________?
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A. Frequency response methods

B. None of these

C. Routh test

D. Root locus methods

148. The offset introduced by proportional controller with gain Kc in response of first order system can be reduced by ____________________?
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A. None of the above

B. Reducing value of Kc

C. Introducing integral control

D. Introducing derivative control

149. Pressure of 0.01 psi (absolute) can be measured by ______________ gauge?
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A. Pirani

B. None of these

C. Mcleod

D. Ionisation

150. Continuous measurement of moisture in paper is done by_______________?
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A. Sling psychrometer

B. High resistance Wheatstone bridge circuit

C. Weighing

D. Hair-hygrometer

151. Smoke density of the flue gas going out of the chimney is measured by a __________________?
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A. Thermal conductivity meter

B. Polarograph

C. Chromatograph

D. Photo electric cell
152. What is the ratio of output amplitude to input amplitude for a sinusoidal forcing function in a first order system ?
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A. < 1

B. 1

C. None of these

D. > 1

153. Pressure of 0.0001 absolute psi can be measured by _____________ gauge?
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A. None of these

B. Thermocouple

C. Pirani

D. Mcleod
154. The temperature of tempering oil baths maintained at 400C during heat treatment of steel is measured by a/an _____________ thermocouple?
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A. Iron-constantan

B. Chromel-alumel

C. None of these

D. Platinum-platinum/rhodium

155. The deflection in diaphragm (which is used as pressure sensor in pneumatic and electronic instruments) is dependent on the metal thickness, its diameter D. and shape & number of corrugations. Its deflection is proportional to_______________?
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A. d2

B. d

C. d3

D. d4
156. According to Bode stability criterion, a system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at frequency for which phase lag is_________________?
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A. 90

B. 45

C. 180

D. 0

157. A simple pitot tube measures the___________________?
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A. Average velocity

B. Point velocity

C. Maximum velocity

D. Static pressure
158. Gas analysis is commonly done using the___________________?
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A. Mass spectrometer

B. Emission spectrometer

C. X-ray diffraction

D. Thermal conductivity cell
159. Which of following error integral is considered as the best criterion in controller settings ?
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A. None of these

B. ?0 ? |e| dt

C. ?0 ? e2 dt

D. ?0 ? |e2| dt

160. The transfer function of a second order system is _____________________?
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A. 1/(T2s2 + 2Ts + 1)

B. 1/(T2s2 + 2?T + 1)

C. 1/(T2s2 + 2?Ts + 1)

D. None of these