HEPA Filter

 

HEPA Filter 

The HEPA filter removes particulates (generally called aerosols) such as micro-organisms, from the air. The HEPA filter does not remove vapours or gases.

HEPA filters used in clean benches and biosafety cabinets should have a minimum filtration efficiency of 99.99% against airborne particles 0.3 microns in size.

It stands for 

- High-Efficiency Particulate Air

- High-Efficiency Particulate Arrestance.

- High-Efficiency Particulate Absorbing

HEPA filters were developed in the early 1940s and used first by the Manhattan Project to contain the spread of airborne radioactive contaminants.

Standards For HEPA Filter

European Standard 

minimum efficiency of 99.95% up to of 0.3 Micron

ACME, U.S. DOE

 minimum efficiency of 99.97% up to  0.3 microns 

Testing & certification standards for HEPA filters

• IEST-RP-CC021 “Testing HEPA and ULPA Media, which governs requirements for the filter media
• IEST-RP-CC001 “HEPA and ULPA Filters”, which governs overall filter construction and labeling requirements
• IEST-RP-CC034 “HEPA and ULPA Filter Leak Tests, which governs HEPA and ULPA filter penetration (leakage) tests
• Testing and certification to meet UL900 flammability requirements

Why 0.3 Micron?

0.3 microns is a benchmark to measure the efficiency of the HEPA filter.

Studies have shown that 0.3-microns is very close to Most Penetrating Particle Size (MPPS) for HEPA filter media. For HEPA filters MPPS range is 0.15-0.25 microns. At MPPS; both impaction & interception are inefficient. 

Efficiency is typically greater than 99.97% against larger or smaller particle sizes. Particles larger than 0.3 microns are more easily trapped, or intercepted, by the media.

Is HEPA filter washable? Can we reuse it?

A washable HEPA filter should be cleaned by rinsing it under cold water.

These filters sold as a permanent filter, so cleaned properly by a vacuum cleaner to remove dust from the surface.

Avoid using water for the HEPA filter.

These filters are made of various fibre which traps dust and another impurity. So proper cleaning of these filters can increase the life of these filters.

Can we use these filters in Air Purifier which is used in Homes?

Yes

Many OEMs are selling purifiers with HEPA filters.

Types of HEPA Filter?

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