System Maintenance & Troubleshooting Flashcards

A technician is troubleshooting an air handling unit where downstream particle counts remain high after filter replacement. What should be inspected next?

Answer: Filter bypass gaps in the housing or rack

Persistent high particle counts after filter replacement strongly suggest air is bypassing the filter through gaps in the housing or rack rather than passing through the media.

What is the primary purpose of maintaining a filter change log with date, differential pressure, and visual condition?

Answer: To provide traceability and support predictive maintenance decisions

A detailed change log provides traceability and enables data-driven decisions about maintenance intervals by revealing loading patterns and anomalies.

A cleanroom HVAC system shows an increase in particle counts only during filter replacement activities. What precaution should be implemented?

Answer: Use bag-in/bag-out filter housings to contain contamination during changeout

Bag-in/bag-out (BIBO) housings allow filters to be removed and replaced without exposing the surrounding environment to the collected contaminants.

A carbon activated pre-filter has lost its odor-control effectiveness but shows minimal pressure drop increase. What does this indicate?

Answer: The carbon adsorbent has reached its saturation capacity

Activated carbon loses adsorption capacity as its pores fill with contaminants; breakthrough occurs before significant pressure drop changes are observed.

During a hot-work permit inspection near a filtration system, why must the maintenance technician ensure the filters are either removed or shielded?

Answer: Filter media may be flammable and pose a fire risk

Many filter media materials, especially synthetic fibers, are combustible and can ignite from sparks or radiant heat generated during hot-work operations.

Which symptom would most clearly indicate a failed fan belt is causing a filtration system malfunction?

Answer: Significant decrease in airflow volume and fan noise changes

A failed or slipping fan belt reduces fan speed, causing an audible change and a measurable drop in system airflow volume.

A technician replaces a filter in a negative-pressure isolation room and airflow arrows confirm correct orientation, yet room pressure turns positive. What should be checked?

Answer: Whether exhaust dampers or fans are functioning correctly

Negative pressure in an isolation room depends on exhaust exceeding supply; a malfunctioning exhaust damper or fan will cause the room to go positive regardless of filter condition.