NCT System Maintenance & Troubleshooting 3

Question 1

A filter housing gasket is found to be compressed and deformed during inspection. What is the primary risk if the gasket is not replaced?

Accepted Answer

Air bypass around the filter, reducing filtration effectiveness

Answer

A deformed gasket cannot create an airtight seal, allowing unfiltered air to bypass the filter media and enter the downstream system.

Question 2

Which tool is most appropriate for field-testing HEPA filter integrity after installation?

Accepted Answer

Aerosol photometer with challenge aerosol

Answer

An aerosol photometer used with a challenge aerosol (such as DOP or PAO) is the standard instrument for scanning and verifying HEPA filter integrity.

Question 3

A technician observes that pre-filters are loading much faster than expected. What operational change would most effectively extend pre-filter service life?

Accepted Answer

Investigate and control the upstream dust source

Answer

Addressing the upstream dust source reduces the contaminant burden on pre-filters, directly extending their service life.

Question 4

During a maintenance shutdown, a technician finds the final filter frame bent and warped. What is the recommended course of action?

Accepted Answer

Replace the filter with a new unit to ensure proper seating

Answer

A bent or warped frame prevents uniform seating against the housing, creating potential bypass pathways that compromise filtration.

Question 5

What is the significance of recording filter differential pressure readings at consistent airflow conditions during each maintenance visit?

Accepted Answer

It enables accurate comparison of filter loading between visits

Answer

Consistent airflow conditions ensure differential pressure readings are comparable between visits, allowing accurate tracking of filter loading trends.

(NCT) NAFA Certified Technician Practice Test

(NCT) NAFA Certified Technician Practice Test

NCT System Maintenance & Troubleshooting 3