NCT Air Filtration Fundamentals & Filter Media

Question 1

What does MERV stand for in air filtration?

Accepted Answer

Maximum Efficiency Reporting Value

Answer

MERV stands for Minimum Efficiency Reporting Value, the ASHRAE standard rating system for air filter efficiency.

Question 2

Which MERV rating range is typically used for commercial buildings requiring superior particulate control?

Accepted Answer

MERV 13–16

Answer

MERV 13–16 filters capture fine particles including bacteria and smoke and are used in commercial settings requiring superior air quality.

Question 3

A HEPA filter must capture what minimum percentage of particles at 0.3 microns?

Accepted Answer

99.97%

Answer

By definition, a true HEPA filter must capture at least 99.97% of particles at the most penetrating particle size of 0.3 microns.

Question 4

Which particle size is considered the Most Penetrating Particle Size (MPPS) for standard air filtration media?

Accepted Answer

0.3 microns

Answer

0.3 microns is the MPPS because particles of this size are too large to follow airstream diffusion yet too small for effective inertial impaction.

Question 5

What filtration mechanism primarily captures large particles (>1 micron) through direct contact with filter fibers?

Accepted Answer

Inertial impaction

Answer

Inertial impaction occurs when large particles cannot follow the airstream around a fiber and collide directly with it.

(NCT) NAFA Certified Technician Practice Test