CPT Instrumentation & Equipment Maintenance 2

Question 1

What is the primary purpose of a thermocouple in process instrumentation?

Accepted Answer

Measure temperature by generating a voltage

Answer

A thermocouple generates a small voltage proportional to the temperature difference between its hot and cold junctions, which is used to infer temperature.

Question 2

A control valve fails to respond to the positioner signal. Which component should be checked first?

Accepted Answer

The instrument air supply pressure

Answer

Insufficient instrument air supply pressure is the most common reason a pneumatic control valve fails to respond to its positioner signal.

Question 3

What does the term 'dead band' refer to in a control instrument?

Accepted Answer

The range of input change that produces no output change

Answer

Dead band is the range over which an input signal can change without causing a corresponding change in output, and it causes hysteresis in the control loop.

Question 4

Which maintenance strategy involves replacing components based on their predicted service life before failure occurs?

Accepted Answer

Preventive maintenance

Answer

Preventive maintenance involves scheduled replacement or servicing of equipment at predetermined intervals to prevent unexpected failures.

Question 5

A pressure transmitter reads higher than expected. After zeroing, the reading is still off-scale. What is the most likely cause?

Accepted Answer

Plugged impulse line

Answer

A plugged impulse line traps pressure and prevents the transmitter from sensing actual process pressure, causing an erroneously high or stuck reading.

(CPT) Certified Process Technician Practice Test

(CPT) Certified Process Technician Practice Test

CPT Instrumentation & Equipment Maintenance 2