chemical engineering process control and instrumentation MCQs – Page 13

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 Review each marked answer and report any item that may be outdated or unclear.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
241. Temperature control of an exothermic chemical reaction taking place in a CSTR is done with the help of cooling water flowing in a jacket around the reactor. The types of valve and controller action to be recommended are________________?
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A. Air to close valve with the controller direct acting

B. Air to open valve with the controller indirect acting

C. Air to open valve with the controller direct acting

D. Air to close valve with the controller indirect acting

242. Routh stability method uses ______________ loop transfer function?
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A. Open

B. Closed

C. Neither A. nor B.

D. Either A. or B.

243. Dome temperature of blast furnace stove is most accurately measured by a____________________?
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A. Platinum resistance thermometer

B. Iron-constantan thermocouple

C. Radiation pyrometer

D. platinum-platinum/rhodium thermocouple
244. For increased speed of response of an expansion pressure spring thermometer, the thermometer bulb should have a__________________?
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A. High thermal conductivity

B. Large area but small mass

C. Small specific heat

D. All A , B & C
245. Liquid flow rate in an open channel cannot be measured by a/an __________________?
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A. Rectangular weir

B. V-notch

C. Cipolletti weir

D. Orifice meter
246. Which of the following shows maximum dip effect (indicating reverse direction of temperature change) ?
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A. Radiation pyrometer

B. Thermocouple

C. Bimetallic thermometer

D. Mercury thermometer
247. Compositional analysis of flue gas coming out of a furnace in respect of O2 and CO2% can be continuously done by a/an___________________?
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A. Thermal conductivity cell

B. Orsat apparatus

C. Chromatograph

D. Zirconia probe

248. Use of I-control along with P-control facilitates ?
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A. None of these

B. Reduction of stability time

C. Reduction of offset

D. Elimination of offset
249. Thermistors which have a very high temperature co-efficient of resistivity belong to the class of solid called________________?
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A. Dielectrics

B. Conductors

C. Insulators

D. Semi conductors
250. _____________ is an example of distributed parameter system ?
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A. Tubular reactor

B. None of these

C. CSTR

D. On-off controller

251. The transfer function for a PID controller is (where, ? i is the integral (reset) time and ?D is the derivative time.) ?
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A. Kc(1 + ?is + (1/?D . s)

B. None of these

C. Kc[1 + (1/?is) + ?D . s)

D. Kc(1 + ?is + ?D ). s

252. Photoelectric pyrometers are suitable in the temperature range of ________________ C?
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A. 800-2500

B. 400-1600

C. 800-1600

D. 400-1000

253. What is the normal percentage of rhodium in platinum + rhodium element used in the thermocouple ?
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A. 29

B. 13

C. 3

D. 0.1

254. Temperature of molten pig iron (1450C) and molten slag (1500C) flowing out of a blast furnace is measured by a/an_______________?
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A. Optical pyrometer

B. Chromel-alumel thermocouple

C. Either B. or C.

D. Radiation pyrometer

255. Which of the following is a desirable characteristic of an instrument ?
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A. High drift

B. Poor reproducibility

C. High measuring lag

D. High fidelity
256. Cascade control means _______________?
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A. One feed-back loop

B. More than one feed-back loop

C. Feed forward control

D. On-off control

257. A mercury barometer measures the _____________ pressure?
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A. Absolute

B. Vacuum

C. Gauge

D. Atmospheric
258. Working principle of radiation pyrometer is based on the __________________?
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A. Stefan Boltzmann law

B. Wiens law

C. Seebeck effect

D. Kirchoffs law

259. Liquid column manometers are used for measuring the pressure ______________ kgf/cm2?
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A. < atmospheric

B. < 10 (gage)

C. > 2 (gage)

D. < 3 (gage)
260. The frequency response of a dynamic element shows a constant magnitude ratio at all frequencies. The element exhibits a negative phase shift at all frequencies. The absolute value of the phase shift increases linearly with frequency. The element has the transfer function ?
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A. (T1S + 1)/(T2S

B. (T1S/(T2S + 1)

C. (T1S + 1)/(T2S + 1)

D. e-?S