Instrumentation & Equipment Maintenance Flashcards
7 cards from real CPT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Instrumentation & Equipment Maintenance flashcards as text
What is the purpose of a snubber on a pressure gauge?
Answer: Dampen pressure pulsations to protect the gauge internals
A snubber uses a restricted orifice or sintered filter to dampen rapid pressure pulsations, preventing gauge pointer flutter and premature mechanical failure.
A flow transmitter using a differential pressure orifice plate reads zero flow even though the process is running. What is the most likely cause?
Answer: Both high- and low-side impulse lines are plugged
If both impulse lines are equally plugged, the transmitter sees equal pressure on both sides and reads zero differential pressure, indicating zero flow.
What type of maintenance philosophy continuously monitors equipment condition to schedule service only when needed?
Answer: Predictive (condition-based) maintenance
Predictive maintenance uses real-time condition monitoring (vibration, temperature, oil analysis) to detect degradation trends and schedule repairs before failure occurs.
When using a megohmmeter (megger) to test a motor winding, what does a very low insulation resistance reading indicate?
Answer: Moisture contamination or insulation breakdown in the winding
A low megohmmeter reading (typically below 1 MΩ) indicates degraded or wet insulation, which can lead to ground faults and motor failure if uncorrected.
Which alarm function in a DCS indicates that a measured variable has exceeded its upper safe operating limit?
Answer: HH (High-High) alarm
The HH (High-High) alarm triggers when a process variable exceeds the second and more critical upper threshold, typically initiating a safety shutdown action.
A globe control valve with an equal-percentage trim is best suited for which process application?
Answer: Flow control where the pressure drop across the valve varies widely
Equal-percentage trim provides a constant percentage change in flow per unit valve travel, making it ideal when the valve pressure drop changes significantly across the operating range.
What is the first action a process technician should take before performing any maintenance on rotating equipment?
Answer: Verify the equipment is properly locked out/tagged out (LOTO)
Lockout/tagout (LOTO) procedures must be applied before any maintenance on rotating equipment to prevent unexpected energization and ensure worker safety.