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  1. #1
    Join Date
    Sep 2009
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    How to verify a filter is HEPA?

    When buying replacement hepa filter for my air purifier, I can pay $55 for the OEM filter, or $30 for an unknown brand from amazon or ebay.

    Since non HEPA filter look similar to HEPA filter, is there a way to test a filter to see if it really is a HEPA filter?

  2. #2
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
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    To qualify as HEPA by US government standards, an air filter must remove (from the air that passes through) 99.97% of particles that have a size of 0.3 m
    put .3 m particles through it in a determined quantity and measure the remaining that pass thru. if you catch 99.97% of them ,you're good.
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"

    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

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  4. #3
    Join Date
    Apr 2005
    Location
    Australia : Queensland
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    Quote Originally Posted by HVAC_Marc View Post
    put .3 m particles through it in a determined quantity and measure the remaining that pass thru. if you catch 99.97% of them ,you're good.
    What he said.

    It should be labelled that it is a HEPA also. Or at least have the filter grade which will refer back to a filter type.
    The primary function of the design engineer is to make things difficult for the fabricator and impossible for the serviceman.

  5. #4
    Join Date
    Nov 2017
    Location
    Seattle, WA
    Posts
    19
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    Looking through this: https://www.engineeringtoolbox.com/p...zes-d_934.html

    The two promising ones I see are carbon black dust, and insecticide dust. Insecticide dust is from I assume crop dusters, but may be hard to spot. Carbon black dust is easier, available online. The particles might be slightly smaller than 0.3 microns, but an 0.3 micron filter should still catch the vast majority of it, while a less severe filter won't.

    You might find it easier and cheaper to buy the filter you trust.

  6. #5
    Join Date
    Dec 2015
    Location
    Austin
    Posts
    119
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    Quote Originally Posted by leakyduct View Post
    When buying replacement hepa filter for my air purifier, I can pay $55 for the OEM filter, or $30 for an unknown brand from amazon or ebay.

    Since non HEPA filter look similar to HEPA filter, is there a way to test a filter to see if it really is a HEPA filter?
    The only way to tell if a HEPA filter is effective is to test and cheapest way to do that is with a Dylos meter. If your looking to save 25 bucks by buying an off brand HEPA I doubt you would be willing to pay 250 bucks for a Dylos. I own one and it's amazing how effective an inexpensive HEPA device can be.

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