Talk:HEPA/Archive 1

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clarification
as defined by the DOE That's not clear whether its the definition of the abbreviation or the definition of filtering efficiency.

The three mechanisms in "In a HEPA filter, particles are trapped (they stick to a fiber) by one of three mechanisms; diffusion, interception or impaction" don't explain themselves. Looking the words up won't help. Perhaps they have specialised meanings in context, but that isn't made clear here. --ToobMug 16:57, 29 December 2005 (UTC)

I agree. The three mechanisms are explained here: [Mechanisms of Filtration http://www.tsi.com/AppNotes/appnotes.aspx?Pid=33&lid=439&file=iti_041] User: Zaytran 23:28, 29 December 2005 (UTC)

Someone suggested adding more information on "the original HEPA filter." Superm401 - Talk 17:41, 23 April 2006 (UTC)

In the first paragraph a flow rate is quoted as 85 L/min. I'm sure these filters come in a variety of sizes and they'll all handle a different flow rate.


 * 85 L/min is the theoretical flow rate for purposes of testing whether a filter meets HEPA qualification. Mention of this in the 2nd paragraph was not intended to specify the operational limits of HEPA filters, though there is likely some bearing.  Do reword this if you find it misleading or augment the content with more detail from other references than the one given.


 * I wouldn't mind seeing some information/references, ideally based on graphs, regarding how the efficiency varies with air flow, and how this applies to different applications such as HVAC (uni-directional) vs. respirators (bi-directional, though either both directions or solely inhalation can be of interest).


 * Of minor concern is that the HEPA mechanisms more or less duplicate content in the article respirator. I couldn't think of how else to add the content at the time so just left it that way.  The respirator list is more extensive as not just HEPA is discussed. -Onceler 00:34, 30 September 2006 (UTC)

HEPA-type/HEPA-like
The air purifier article basically says "BEWARE of those that say 'HEPA-type'", but can anything be known about a filter that is labeled as such? What do they mean by "HEPA-type"? It seems they would be limited in saying that by false advertising laws unless it had something in common with real HEPA filters. What is that something? — Omegatron 21:21, 25 October 2006 (UTC)
 * "HEPA-like" or "HEPA-type" filters are just as you said: non-conventional advertising practice. That "something" is maybe only the shape (pleated) and these filters actually yield a lower efficiency. True medical HEPA filters are all laser-tested and should remove 99.97% of all particles greater than 0.3 microns. The test is done using DOP and if not passed, they are not issued a certificate. Usually, "HEPA-like" filters have an efficiency of 95% (as advertised by some "fairer" companies) but no one really knows the actual efficiency unless tested. The Vindictive 08:27, 12 April 2007 (UTC)
 * Blueair has a proprietary brand called HEPAsilent. Its essentially a MERV 8 or 9 filter once the carbon runs out, and the electrostatic charge in the filter medium is depleted. And since their purifiers lacks any form of ionizers, static or any form of ground to the filter medium, quality is going to be different the first 2-3 weeks and rest of the filters lifetime without functional carbon. There is nothing unique about Blueair. The primary sales purpose of a Air Filter for home usage is to get rid of visible floating dust, while the secondary purpose is to get rid of particles of building materials or pollen. A better filter means you need a bigger fan, or make the device silly loud. Skimping on the filter is the simplest way to fix the problem, but it also means you can't trust the device's rating if its not HEPA or MERV.--Stalkerkun (talk) 21:56, 9 August 2021 (UTC)

Graph
So it picks up particles above and below 0.3 um? We should have a graph of that, like — Omegatron 21:41, 25 October 2006 (UTC)

hepafilter.com
Perhaps we should delete this link? It does not provide any information about hepa filters, but seems mostly to be a commercial site. VitaminE 23:35, 17 December 2006 (UTC)

correct expansion of the abbreviation
Correct expansion of the abbreviation (acronym) is "high-efficiency particulate-arresting" (filter).

Yes, and when I corrected the article to the correct acronym, it was reverted. What gives? —Preceding unsigned comment added by 128.2.161.180 (talk) 17:41, 31 October 2007 (UTC)


 * I suggest finding a modern, authoritative reference giving that expansion. The expansion used most commonly, and therefore most likely correct in the absence of a clearly authoritative source to the contrary, is "High Efficiency Particulate Air." Since "HEPA is commonly followed by the word "filter" this certainly makes sense.  Pzavon 00:20, 1 November 2007 (UTC)

When I first encountered the acronym and term decades ago, it was "High Efficiency Particulate Arrestor" without the need to append 'filter' as "Arrestor" says most if not all it needs to say. Arrestance isn't even an English word. — Preceding unsigned comment added by 220.235.226.215 (talk) 06:04, 17 March 2016 (UTC)

links
This is helpful: the CFR that covers N100 filters http://www.cdc.gov/niosh/pt84abs2.html comment added by User talk:Quincy8Boy on 20 June 2007


 * Both N/P100 and N/P99 would have been called "HEPA" in the past. This NIOSH regulation establishes a designation scheme for particulate filters that moves away from, and in fact does not use the term "HEPA" at all.  Pzavon 02:53, 21 June 2007 (UTC)

HEPA 11, 12 and 13
In many cases vacuum cleaner manufacturers add a number after the HEPA designation: 11, 12 or 13. Anyone know what this refers to? Benkeboy (talk) 10:02, 19 December 2008 (UTC)
 * In an email from Electrolux I got the answer that HEPA 12 removes 99.5% of particles larger than 0.03 micron, HEPA 13 filtrates even smaller particles. The extension "W" means washable. But still have not found any standards for this or any other document with same or similar info. Benkeboy (talk) 10:58, 30 December 2008 (UTC)
 * That seems unlikely as a general proposition. HEPA is defined as a filter that will remove 99.97% of particles 0.03 microns in size.  Since that size is the most difficult to filter, a basic HEPA filter will be more that 99.97% effective at removing particles larger than 0.03 microns AND less than 0.03 microns in size.  This has been confirmed through testing and even seems to hold true into the nanoparticle range.  Perhaps the HEPA 12, HEPA 13, etc., designations are one manufacturer's method of marketing a "not quite HEPA" product.  Pzavon (talk) 20:53, 30 December 2008 (UTC)
 * According to the article a HEPA filter can remove at least 99.97% of particles larger than 0.3 micron. According to the manufacturer HEPA 12 removes particles a factor 10 smaller, although at 99.5 rather than 99.97%. 193.137.16.117 (talk) 21:39, 2 January 2009 (UTC)
 * Thanks. I read that as sales hype by the manufaturer since all HEPA filters will do that.  Pzavon (talk) 16:42, 3 January 2009 (UTC)

A possible explaination is that the number is refering to the filter's MERV rating. AKA a MERV 12, MERV 13, or MERV 14 filter. A HEPA boosts a MERV 17 ranking. A MERV 12 removes roughly 90% of particles while a MERV 15 will remove >95%. —Preceding unsigned comment added by 131.204.140.40 (talk) 20:37, 19 June 2009 (UTC)

As Electrolux is an European company they use the classification of HEPA 10, 11....14 according to an European Standard EN1822. The HEPA 13 class is near by the DOE used HEPA specification. This EN1822 will come in a new revision end of 2010. The class 10-12 will be called EPA then. Additional they will change the test methods, so that it will be impossible to use polymer filter media in advance. (nobody understands this, but may be the glass fibre industry had too large influence.) 如何解决hepa使用效果逐渐递减的问题. — Preceding unsigned comment added by 60.2.179.150 (talk) 01:06, 17 December 2013 (UTC)

Washable HEPA
I've noticed that some companies are selling washable HEPA filters in their various uses and I'm curious about how they compare to the kind that are disposed of. If anyone can find more info on them I think it should go in the main article. —Preceding unsigned comment added by 66.27.124.108 (talk) 22:47, 31 December 2008 (UTC)

My vacuum cleaner has a HEPA filter which the instructions say traps particles by electrostatic attraction. The instruction is wash the filter under a cold tap, do not use any washing up liquid as this will destroy the attraction. The filter is a foam plastic that easily compresses. Here is a link to one page of the manufacturers website that gives a little detail for a later model of cleaner : http://www.dyson.co.uk/store/product.asp?product=DC33-IRWH and here is the most popular filter as a spare part http://www.dyson.co.uk/store/partsDetails.asp?part=ACC-DC07FILTER-WASH&product=DC07. I see two revisions to the article as necessary :- electrostatic attraction is required as a mechanism and foam plastic is required as a material. I do not know exactly how this works, but I do know that bringing a dust particle against a surface generates a strong difference of electrical potential. So the dust should be attracted to the filter. Throwing the dust at the surface introduces another mechanism ; the dust is hotter and so yields electrons. I suspect that all that is required is a very good insulator for the foam. And certainly washing up liquid would never dry as the liquid is hygroscopic, this destroys the surface insulation of anything it touches. Reg nim (talk) 19:30, 25 November 2011 (UTC)

Airline Usage
The Air Transport Association would like to add a section about how HEPA filters remove airborne contaminants on airline flights. In the interest of ensuring the page's neutrality, we would like to know if any other editors would like to work with us to update this article. If there is no interest, we will work to ensure that our revisions fall in line with Wikipedia's standards of neutrality, no original research and verifiability. Lanekedc3 (talk) 20:59, 4 May 2009 (UTC)
 * I googled about this subject and it seems that the info, that I deleted, was from a Boeing website and exaggerated how safe airplane air is. Read this WSJ article: http://blogs.wsj.com/middleseat/2009/05/01/swine-flu-and-travel-qa-on-infectious-diseases-in-airline-cabins/ Airplane air is not as safe as air in your home or in an industrial "clean room", this is corporate propaganda. Read from that link about all those flights where SARS or the flu for example spread among lots of passengers even on flights as brief as 3 hours. Wicksteed100 (talk) 15:46, 22 February 2012 (UTC)Wicksteed100

NIOSH Filter Definitions N, P, and R and MERV Information
Please note also that in NIOSH filter definitions (http://www2.cdc.gov/drds/cel/cl.htm), the N-class filters are particulate, oil-free *only*, whereas the P-class filters are for all particulates, including oil droplets (why they're so much more expensive than "mere" N-class), and the newer R-Class seem to be also against all particulates but with a time limit (due possibly to degradation?). This is the 1st I've heard of an R-class; last time I checked filters was in 2003-04, and never saw a mention, so they must be rather new?

MERV ratings seem to refer to furnace/central air conditioner filters, (http://www.furnacefiltercare.com/merv-ratings.php). Per my referencing web page, a MERV furnace filter comparable to a HEPA filter would actually be about a MERV 16, or higher, to meet HEPA's 99%+ efficiency of 0.3 micron particulates.

Ryoverde (talk) 20:08, 9 September 2009 (UTC)

hepa replacement
when hepa filter has to b replaced? —Preceding unsigned comment added by 59.92.188.250 (talk) 10:23, 10 December 2009 (UTC)

A HEPA filter is to be replaced when dirty or aged, with specific time given by manufacturer or regulatory institution. An example can be found in filters for a home heater, which have a "replace after" listed with something like "after X months" with the X replaced with what ever the filter was meant for. I personally don't believe that the idea of replacement should be discussed in the article but if someone feels diffently, then I certainly won't delete the section. Ausimeman21 (talk) 01:57, 20 November 2011 (UTC)

diagram
I like the diagram, but the explanation of the different mechanisms doesn't make sense. < 0.1 micron = < 100 nm. So which mechanism predominates? Consider correcting this and sorting the mechanisms on particle size. —Preceding unsigned comment added by 85.149.64.49 (talk) 10:12, 27 March 2010 (UTC)

Function and Specifications
I put them under separate headings. Seems more readable to me that way. Paragraph about the European Norm (copied from German Wikipedia) could do with some references.It appears that the EN is only available for purchase. —Preceding unsigned comment added by 213.23.163.134 (talk) 17:41, 5 July 2010 (UTC)

Microns or Micrometers?
A micrometer is 1000th part of a millimeter ( or 1000 000 th part of a meter) and is known as micron. There is another unit, which is very commonly used i.e. 1/1000 th part of one inch. This unit is commonly called as mil. Relationship between these units can be easily seen. one mil is equal to 25.4 microns. 39.37 (approx 40) mils are equal to 39.37x25.4 microns = 1000 microns or 1 millimeter. Devkumarbansal (talk) 11:50, 18 October 2013 (UTC)

"5.2.1 Penetration: Aerosol penetration for any HEPA filter shall not exceed 0.03% (0.0003) at 0.3 micrometer particle size."

Going on the assumption that this is the correct spec, I shall endeavor to make the necessary corrections to the article, replacing all instances of "micron" with "micrometer".

Only once instance found and corrected. Onerock (talk) 04:08, 15 September 2011 (UTC)

Please confirm your conversion between microns and micrometers. According to two sources I accessed, including another page in Wikipedia, the two units are one in the same and can be used interchangeably. The Wikipedia link I refer to is: http://en.wikipedia.org/wiki/Micrometre  — Preceding unsigned comment added by 72.49.96.68 (talk) 20:32, 18 November 2012 (UTC)

Broken links
US Department of Energy HEPA website US Department of Energy Specification for HEPA Filters Used by DOE Contractors, 1997 Onerock (talk) 04:01, 15 September 2011 (UTC)

How the same and how different from automotive engine air cleaners?
I've just looked at a Honeywell home HEPA filter, and it looks a lot like an air cleaner for a car engine: basically of the same gross structure. I suppose the difference is in the material used. Could we get some text in the article explaining how the two are the same and how they are different? Thanks.CountMacula (talk) 07:17, 23 April 2014 (UTC)

Acronym expansion
At various times, the expansion of HEPA has been given as "high-efficiency particulate arrestance", "high-efficiency particulate arresting", or "high-efficiency particulate air", among others. The article currently features two of the alternative names. Please do not change or remove any of them without first discussing the choices here. I don't hold a dogmatic position on the names, but think that all commonly-seen names should be given in the article. If you believe that a given one is more "correct" or others are "erroneous", please cite some WP:RS to back your claim. Do not remove an alternative name without discussing it with other editors. Reify-tech (talk) 23:07, 14 July 2015 (UTC)

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Mathmatical relation for efficiency and volume flow rate — Preceding unsigned comment added by 59.185.105.29 (talk) 04:55, 3 October 2016 (UTC)

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Copied Portion of Intro to Air filter
SKay (talk) 11:19, 3 March 2019 (UTC)

Clarification needed: we don't see the difference between Diffusion - Interception - Impaction
We are two (educated) people, and we don't understand the differences. The text and the pictures don't help. If you understand it, please try to make it clear for the others. User67QH (talk) 07:18, 14 April 2020 (UTC)
 * I can see where you are coming from. In addition, in the "Mechanism" section, three mechanisms are mentioned. In the "Filtration Mechanisms" illustration however, four mechanisms are mentioned. Thus in addition to a more comprehensive respectively more comprehensible explanation of its modes of operation, it would be helpful for said discrepancy to be dispelled. lmaxmai, 31 May 2020 (UTC)

Commons files used on this page or its Wikidata item have been nominated for deletion
The following Wikimedia Commons files used on this page or its Wikidata item have been nominated for deletion: Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 12:06, 8 February 2021 (UTC)
 * Display VSON WP6910 (air detector) - pm2,5 at Verona (Borgo Milano) Italy - (particulate pollution, polveri sottili) - 2020 01 30 (hour 22-37) - OUTdoor and INdoor (HEPA H13 filter) - first publication commons.wikimedia.org.webm
 * Filtro HEPA protetto da prefiltro estratto dal VMC - Dopo 10 giorni - Ogni lato era bianco (lato nero è smog fine) - 2020 01 14 a Verona (Borgo Milano) by Paolo Villa.webm

HEPA filter image/description
I’m not certain if “material” is the best word… “matrix” might be more accurate. I changed “matra” to “material”, but I’m wondering if “matrix” might not be more accurate… thoughts anyone? Jd.varner44 (talk) 22:23, 30 September 2021 (UTC)