NCT Air Filtration Fundamentals & Filter Media 3

Question 1

For a hospital operating room requiring the highest level of particle control, which filter rating is most appropriate for the final filtration stage?

Accepted Answer

ULPA (U15 or higher)

Answer

ULPA filters capture 99.999% of particles ≥0.12 microns and are used in the most demanding cleanroom and surgical environments where HEPA alone may be insufficient.

Question 2

When selecting a pre-filter upstream of a high-efficiency final filter, what is the primary design goal?

Accepted Answer

To extend the service life of the more expensive final filter

Answer

Pre-filters capture larger particles first, protecting the costly high-efficiency final filter from premature loading and extending its replacement interval.

Question 3

According to NAFA guidelines, what is the recommended action when measured static pressure drop across a filter exceeds the manufacturer's specified terminal pressure drop?

Accepted Answer

Replace the filter immediately

Answer

Exceeding the terminal pressure drop means the filter is fully loaded; continued use reduces airflow and system performance, so replacement is required.

Question 4

Which standard governs the test method for HEPA and ULPA filter efficiency using a polydisperse aerosol?

Accepted Answer

ISO 29463

Answer

ISO 29463 (and its predecessor EN 1822) defines the test methods for high-efficiency air filters (HEPA and ULPA) using a polydisperse aerosol challenge.

Question 5

A filter bypass occurs when air travels around rather than through the filter media. The most common cause is:

Accepted Answer

Improper filter fit or damaged filter frame gaskets

Answer

Improper fit or damaged gaskets allow unfiltered air to flow around the filter, rendering even a high-efficiency filter ineffective.

(NCT) NAFA Certified Technician Practice Test

(NCT) NAFA Certified Technician Practice Test

NCT Air Filtration Fundamentals & Filter Media 3