Fermentation Technology Multiple Choice Questions on “Instrumentation and Control – Temperature and Pressure Measurement”.
1. Which of the following sensor penetrates into the fermenter?
A. Exhaust-gas analyzers
B. pH electrodes
D. Load cellsid5fdc7db6440c4″
Clarification: The sensors which penetrate into the fermenter are pH electrodes, dissolved-oxygen electrodes, etc. Exhaust gas analyzers work on samples which are continuously withdrawn from the fermenter. Tachometers and Load cells are sensors which do not come in contact with fermentation broth or gases.
2. Which of the following sensor is used to measure the acid/alkali addition?
Clarification: The pH is defined as the potential of the hydrogen atom. It is used to measure the concentration of hydrogen or hydroxide ions in a solution. pH electrodes are normally used to measure the acid/alkali addition.
3. Which of the following sensor is used to measure the change in flow rate?
C. Medium analysis
D. Exit-gas analysisid5fdc7db6440f3″
Clarification: Weight sensors are used to measure the change in flow rate. Along with weight sensors the flow rate sensors are also used to measure the change in flow rate. Temperature is used to measure the hotness or coldness of the medium. Whereas the medium and exit-gas analyzers are used to measure the change in feed rate.
4. The heat control at large-scale in the fermenter is carried out by _________
A. Inter heating coils
B. Heating jacket
C. Controlled bath
D. Cold-water circulationid5fdc7db6440fe”
Clarification: The heat control at large-scale in the fermenter is carried out by cold-water circulation or internal coils. The heat control at small-scale in the fermenter is carried out by a silicone heating jacket, controlled bath, etc.
5. Which of the following temperature sensors is not used for a temperature measurement?
A. Non-electrical type
B. Electrical type
C. Magnetic type
D. Radiation typeid5fdc7db644107″
Clarification: There is no such magnetic type used for the measurement of temperature in the fermentation. The non-electrical type, electric type, radiation types are usually used to measure temperature in fermenters.
6. The resistance _________ with increase in temperature.
C. Becomes constant
D. Becomes zeroid5fdc7db644110″
Clarification: The resistance of the material increases with an increase in temperature. This happens because the temperature is directly proportional to the change in temperature.
7. Which of the following is made up of mixtures of pure oxides of iron and nickel?
B. Mercury thermometers
C. Radiation thermometers
D. Metallic thermometersid5fdc7db64412e”
Clarification: Thermistors are the semiconductors that are made up of pure oxides of iron, nickel or other metals. They exhibit a large change in resistance with a small temperature change. They are highly sensitive with small temperature changes.
8. Which of the following devices is not used for pressure measurement?
A. Diaphragm gauge
B. Pressure bellows
C. Strain gauge
Clarification: The devices used for the measurement of pressure is diaphragm gauge, strain gauge, pressure bellows, piezoelectric transducer, etc. The dynamometer is useful in agitation measurement and control.
9. Who invented the Bourdon tube?
Clarification: Eugene Bourdon in 1949 invented the Bourdon tube. It has been used in pressure measurement in many processes like fermentation. It is used as a direct indicating gauge.
10. Which of the following measures the pressure with change in electrical resistance?
A. Bourdon tube
B. Pressure bellows
C. Strain gauge
D. Diaphragm gaugeid5fdc7db64414c”
Clarification: The strain gauge measures the pressure with a change in electrical resistance. It uses a wire subjected to strain result in the change in electrical resistance which can be measured.
11. Which of the following sensor is not a part of the fermenter?
Clarification: Offline sensors are the sensors that are not an integral part of the fermenter. The measured value must be entered for data collection. The on-line and in-line sensors are the integral parts of the fermenter.
12. Which of the following parameters is not useful in the construction of pressure bellows?
B. Sensitive to changing pressures
Clarification: The parameters which are kept in mind while constructing pressure bellows are Hysteresis, sensitive to changing pressures, corrosion, range of pressure, fabrication ease, fatigue on the dynamic operation.
13. Ion-specific sensors are the types of on-line sensors.
Clarification: The ion-specific sensors are the type of on-line sensors and are an integral part of the fermenter. The measured value is entered into the control system for controlling the process.
14. Antifoam probe is a type of off-line sensor.
Clarification: The antifoam probe is a type of in-line sensors. They are an integral part of the fermenter. It is used to check the foam formation in the fermenter and control it.
15. If the two metals have different temperature coefficient then, they are useful in making _________
A. Manometric thermometer
B. Gas thermometer
C. Bimetallic thermometer
D. Digital thermometerid5fdc7db64417b”
Clarification: The bimetallic thermometer consists of a bimetallic strip which has a different temperature coefficient. It is used to convert temperature into mechanical displacement.