BASIC INSTRUMENTATION AND CONTROL QUESTION ANSWER

BASIC INSTRUMENTATION AND CONTROL QUESTION ANSWER (PART-I)

1. What is an instrument?

• Instrument is a device which is used for measurement, monitoring, controlling, and display of process variables. 

2. What is instrumentation?

• Instrumentation is a branch of engineering which deals with measurement, monitoring, controlling, and display of process variable.

3. What are the process variables?

• Temperature, pressure, level, flow

4. What are the types of permits?

• Cold work permit, hot work permit, confined space permit

5. What are the cold work permits?

• Installation, loop checking, field calibration, function test, troubleshooting

6. What are the hot work permit?

• Welding, cutting, drilling

7. What are the type of fire extinguisher?

• Water, powder,  foam, carbon dioxide

8. What is temperature measurement?

• It is to be measure hotness or coldness od the process medium

9. Units of temperature

• Degree Celsius, degree Fahrenheit, kelvin, ranking

10. Conversion of temperature units

◦C = 

◦F = 

11. What are the temperature sensor elements?

• RTD, Thermocouple

12. What is means by PT 100?

• When temperature is 0 degree Celsius, resistance is 100 ohms

13. What are type of RTD?

• Two wore RTD, Three-wire RTD, Four-wire RTD

14. What is the output of RTD?

• Output of RTD is Resistance in Ohm

15. What will be the resistance at 100 degrees Celsius?

• 138.5 ohm

16. What is the output of thermocouple?

• Millivolts(mv)

17. What is the principle of thermocouple?

• Seebeck effect, Peltier effect, Thomson effect

18. RTD PT 100 Charts

19. What is the Seebeck effect?

• When heat is applied to the hot junction, millivolts is generated at the cold junction 

20. What are the types of thermocouple?

21. What is the specially of thermocouple lead wire?

• lead wire should be of the same material as the thermocouple metal material.

22. How to check TT(T/C input) without connecting thermocouple or millivolt source?

• connect short link at the thermocouple input terminal(+) and(-) of TT. TT should show temp if TT shows room temp TT is ok.

23. What is a skin Thermometer?

• skin thermometer are those which directly connected to the process without any thermowell. It is used for measuring the skin temperature of the heater, furnace, and boiler.

24. How to calibrate temp RTD and Thermometer?

• Keep temp sensor (RTD or T/C) in temp bath
• Connect multimeter at the sensor terminal.
• Set temp on temp controller in temp bath
• check resistance or millivolt in multimeter according to set temp.
• For RTD, if temp is 100 degree Celsius then check resistance on multimeter138.5 ohms
• For thermocouple, if temp is 100-degree celsius then check millivolts on multimeter.

25. Why thermowell is used?

• Thermowell is used to avoid direct exposure to the process to protect from corrosion, erosion, and high-pressure process. Also to protect from physical damage during handling and normal operation.