Predictive Maintenance Techniques Flashcards

In lubricant oil analysis, a sharp increase in iron particle count combined with a high particle size distribution skewed toward larger particles most likely indicates:

Answer: Severe adhesive or abrasive wear in progress

Large iron particles in high concentration signal active, severe wear (adhesive or abrasive), which requires immediate investigation, unlike the fine particles typical of normal run-in.

Infrared thermography on an indoor low-voltage switchgear panel is most effective at identifying which type of defect?

Answer: Loose or corroded electrical connections causing resistive heating

Loose or corroded connections increase contact resistance; IR thermography detects the resulting heat signature before the connection fails, making it the primary electrical PdM tool for connection integrity.

Airborne ultrasonic inspection is particularly useful for detecting which condition in compressed air systems?

Answer: Small leaks at fittings, valves, and hoses

Gas leaks through small orifices generate broadband turbulence with strong ultrasonic components; an ultrasonic detector can locate these leaks that are inaudible to the human ear.

Ferrography (analytical ferrography) in oil analysis provides information that routine spectroscopy does NOT, specifically by:

Answer: Allowing visual examination of wear particle morphology and size

Analytical ferrography separates and deposits wear particles on a substrate for microscopic examination, revealing particle shape, size, and surface features that identify the wear mechanism.

During an infrared inspection of a steam trap, which thermal condition indicates a failed-open (blowing) steam trap?

Answer: High inlet temperature with similar high outlet temperature

A failed-open trap continuously passes live steam, so the outlet pipe temperature approaches the inlet temperature instead of showing the expected temperature drop across a functioning trap.

A lubricant's viscosity index (VI) is a measure of:

Answer: How much the viscosity changes with temperature variations

Viscosity index quantifies the sensitivity of a lubricant's viscosity to temperature change; a high VI means viscosity changes little across a wide temperature range.

When using contact ultrasound to inspect rolling element bearings, what does a loud, irregular crackling or 'frying' sound in the headset typically indicate?

Answer: Early-stage bearing damage such as spalling or pitting

Irregular crackling or frying sounds in ultrasonic bearing inspection are caused by stress waves generated when rolling elements strike defects such as spalls or pits on race surfaces.