NCT Installation Standards & Best Practices 3

Question 1

When installing HEPA filters in a critical environment, which test is performed in-place to verify filter integrity after installation?

Accepted Answer

DOP/PAO aerosol challenge scan test

Answer

An in-place DOP (dioctyl phthalate) or PAO (poly-alpha-olefin) aerosol scan test is the industry-standard method to verify installed HEPA filter integrity and detect pinhole leaks or frame bypass.

Question 2

What is the maximum allowable installed filter penetration per IEST-RP-CC034 for a HEPA filter scan test?

Accepted Answer

0.01%

Answer

IEST-RP-CC034 specifies that the maximum allowable local penetration during a HEPA in-place scan test is 0.01% of the upstream concentration.

Question 3

According to NAFA guidelines, which type of duct liner should NOT be installed immediately downstream of the final filter in a critical application?

Accepted Answer

Exposed fiberglass duct liner

Answer

Exposed fiberglass duct liner downstream of the final filter can shed fibers into the clean air stream, contaminating areas the filtration system was designed to protect.

Question 4

What problem occurs when a filter holding frame is installed out of plumb in a vertical filter bank?

Accepted Answer

Filters may sag, causing bypass gaps at the top or sides

Answer

An out-of-plumb frame allows filters to sag or shift under gravity, opening gaps that permit unfiltered air bypass and reduce filtration efficiency.

Question 5

What is the recommended minimum overlap between a filter gasket and its mating surface on a holding frame?

Accepted Answer

1/4 inch

Answer

A minimum 1/4-inch gasket contact with the frame mating surface ensures a reliable seal against bypass under operational static pressures.

(NCT) NAFA Certified Technician Practice Test

(NCT) NAFA Certified Technician Practice Test

NCT Installation Standards & Best Practices 3