CPT Instrumentation & Equipment Maintenance 4

Question 1

What is the purpose of a snubber on a pressure gauge?

Accepted Answer

Dampen pressure pulsations to protect the gauge internals

Answer

A snubber uses a restricted orifice or sintered filter to dampen rapid pressure pulsations, preventing gauge pointer flutter and premature mechanical failure.

Question 2

A flow transmitter using a differential pressure orifice plate reads zero flow even though the process is running. What is the most likely cause?

Accepted Answer

Both high- and low-side impulse lines are plugged

Answer

If both impulse lines are equally plugged, the transmitter sees equal pressure on both sides and reads zero differential pressure, indicating zero flow.

Question 3

What type of maintenance philosophy continuously monitors equipment condition to schedule service only when needed?

Accepted Answer

Predictive (condition-based) maintenance

Answer

Predictive maintenance uses real-time condition monitoring (vibration, temperature, oil analysis) to detect degradation trends and schedule repairs before failure occurs.

Question 4

When using a megohmmeter (megger) to test a motor winding, what does a very low insulation resistance reading indicate?

Accepted Answer

Moisture contamination or insulation breakdown in the winding

Answer

A low megohmmeter reading (typically below 1 MΩ) indicates degraded or wet insulation, which can lead to ground faults and motor failure if uncorrected.

Question 5

Which alarm function in a DCS indicates that a measured variable has exceeded its upper safe operating limit?

Accepted Answer

HH (High-High) alarm

Answer

The HH (High-High) alarm triggers when a process variable exceeds the second and more critical upper threshold, typically initiating a safety shutdown action.

(CPT) Certified Process Technician Practice Test

(CPT) Certified Process Technician Practice Test

CPT Instrumentation & Equipment Maintenance 4