Why Do HEPA Filter Have 0.3 Micron Pore Size?
High efficiency particulate air filters are used to maintain the area cleanliness in classified area. Pore size of these filters is always 0.3 microns.
HEPA filters use a four-step process to purify air:
- Initial Particle Removal: Larger particles are captured through sieving and inertial impaction as air flows into the filter.
- Fine Particle Filtration: Air passes through a finer mesh of fibers, trapping smaller particles effectively.
- Collision Filtration: As air continues through the filter, remaining particles collide with the fibers and become trapped.
- Final Output: The air that exits the HEPA filter is highly purified, removing up to 99.97% of particles, including those as small as 0.3 microns.
The smaller the micron, the harder it is to filter out of the air.To understand, the human eye detects particles around 10 microns, like pollen or plant spores. Bacteria, however, can measure as small as 0.3 microns—far beyond the reach of standard filters. Industrial HEPA filters, capable of capturing particles at this microscopic level, are essential in environments like pharmaceutical companies, where maintaining sterile air is critical. Bacteria can be as small as 0.3 microns, which is why 0.3 micron industrial HEPA filters are used in pharma companies.
What is MPPS in a HEPA filter?
The MPPS is the “most penetrating particle size.” It’s the hardest size of particle to capture.
It’s NOT the smallest particles. The smallest particles (like .01-micron particles) are SUPER easy to capture (because of Brownian motion). And it’s not the biggest particles either. Big particles like a grain of sand or a human hair are also really easy to capture (because of the net).
The hardest particle to capture is in between those two—around 0.3 microns. Those particles are small enough to fit through the filter fibers, but they’re large enough to fly in relatively straight lines. The most penetrating particle sizes (MPPS) for HEPA filters is the hardest particle size to capture, often around 0.3 microns.
Read also: HVAC Qualification Process
Resource Person: Vikas Bedi
