Basic instrumentation Interview questions?



1.What is instrumentation ?

Instrumentation is a study of instruments used for indicating ,measuring,recording ,controlling the process variable is called instrumentation .The process variables commonly used in industries are Temperature, Humidity, Flow, Level, Pressure,pH,density etc

2.Define range?

Distance between zero and span is called range.

3.Define zero?

Minimum value of range is zero.

4.Define span?

Maximum value of range is called span

5.What is absolute pressure?

It is the total pressure in the system
absolute pressure =Gauge pressure + atm pressure.

6.What are the types of pressure measuring methods in electronics transmitter?

Resistance type,capacitance type,inductance type

7. An electronic pressure transmitter range 0-60psi .what will be the output at 24 psi?


step: (24/60)*16+4=10.4ma

8.What are the commonly used manometer liquids ?


9.Explain calibration procedure of DP transmitter?

a) Adjust zero of the transmitter
b) Static pressure test:give equal pressure on both side of the transmitter .
zero should not shift .if it is shifting carry out static alignment.
c) vacuum test :apply equal vacuum on both side the zero should not shift.
d)Calibration procedure:give 20psi air supply to the transmitter ,vent LP side to atmosphere.
e) apply required pressure to HP side of the transmitter an adjust span
f) adjust zero again if necessary.

10.Generally for a temprature control _________action will be suitable.
Derivative action