Four Mechanisms of HEPA Filters

HEPA stands for High Efficiency Particulate Air. It is an air filter that provides a very high level of

filtration efficiency. It can capture at least 99.97% of air contaminants at 0.3 micron size. It can trap the

largest and smallest particulate contaminants to ensure a pure and clean air for you. It will filter

harmful pollutants and allergens of the air. This filter works by circulating the air to purify it. HEPA

was introduced by the U.S. Atomic Energy Commission with the aim to remove the airborne

radioactive particles from the air. An air filter is necessary because whether you are indoor or outdoor,

the air is polluted. It can cause allergic reactions including headaches, red eyes, digestive problem,

dizziness, congestion and other chronic diseases. But with HEPA filters you can sleep better and have

more energy to live a healthier life.

What are HEPA filters?

It is composed of a mat of randomly arranged borosilicate fibers. The fibers are composed of fiberglass

and has a diameter between 0.5 and 2.0 micrometers. HEPA filters are designed to trap air particles

that contaminate the air and circulate pure and clean air. It is made possible with the following

mechanisms:

Inertial Impaction

◦ It works on large and heavy particles that are suspended in a flow stream. It is a direct way

of blocking the particulates via the medium filter. The particles are heavier than the fluid

that surrounds them. This mechanism is intended for heavy particles because it is unable to

adjust to the abrupt changes in the streamline direction. The heavy particles will move in a

straight line (inertia) and hit the filter fiber. Hence, air particles are trapped releasing only

clean air.

Diffusion

◦ It works on the smallest particles that are not held in place by the viscous fluid and simply

diffuses within the flow stream. It works on the kinetic theory of gases in which molecules

behave like ridged spheres that collide with each other and move in random like a zigzag

path called the Brownian motion. Diffusion is dominant with low gas velocities and the

slower the motion of the molecules is the greater is the chance that it will have to zigzag

around, hence, providing a higher chance of hitting and colliding with a filter fiber.

Interception

◦ It works with mid-range size particle that are not large (no inertia) and not small (to diffuse)

enough to be captured with inertial impaction and diffusion. The mid sized particles will

bend through the fiber space and will be captured once they pass through it.

Sieving

◦ It is a mechanism that happens when the particle is big enough to fit between fiber spaces. It

is a simple way of separating unwanted particles in the air.

HEPA filters are known to be the most efficient air filter. With the mechanisms it uses to ensure that

you get a clean air, you can breathe confidently. HEPA filters from cleanairplus.com ensure a healthy,

clean and pure indoor air to keep you safe from air contaminants that cause diseases.