[OP]
Member
What does it mean when a dust collector is advertised to have a "1 micron" filter? I don't know what a "1 micron" filter is. I can't find any industry or government standards or test methods that define a micron rating for air filters. Everything I've seen rates collection efficiency.
So, I'd really like to hear your opinion on the meaning of a "micron rating" for a dust collector filter. My opinion is that it's just marketing fluff that has no defined meaning.
What do you think?
Beranek's Law:
It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.
Moderator
What the term refers to is the smallest particles that can go through the filter. A 1 micron filter will "catch" particles that are at least 1 micron in diameter (or equivalent odd-shaped) and anything smaller will pass through. The lower the number, the finer the filtration.
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The most expensive tool is the one you buy "cheaply" and often...
Member
It is confusing because some reference material says a micron is .000001 of a meter and some says .001 of a meter. One Micro is .000001 but micron does seem to have a life of its own depending on what you read.
Contributor
That's the way I've always understood it, but since it's not qualified it's basically marketing fluff. (Does it capture 95%, 99%, 99.9% of the 1 micron particles?)Originally Posted by Jim Becker
That's just wrong. Micron is very well defined. Some of the references you are remembering are incorrect, I can't say whether typo or ignorance. 1 micron is 0.000001 meter, or 0.001 millimeter.
Contributor
Most such filters get better as a dust cake builds up and plugs any bigger holes. With N95 masks there is a static electric effect or something like that. The physical holes are larger then the particles that can get through. Washing in fabric softener cancels that out and they no longer filter as well.
I think pressure differential and velocity also play into the filters ability as well. I have never noticed a filter rated for pressure except for liquid filters.
Bil lD
Contributor
Try to get OSHA approval or meet some regulatory standard, you'll find it is a definite definable, measurable standard.
Member
You may find the information below useful
https://en.wikipedia.org/wiki/Minimu...eporting_value
[OP]
Member
Yes, that is the spec normally used for rating air filters in the US. The output of the test procedure is not a micron rating but rather a MERV rating. It does not define a micron rating.
As far as I can tell, a dust collector filter claims say, 2 micron filtering is using a made up number. There's no defined test standard for that "rating".
Beranek's Law:
It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.
[OP]
Member
You've seen a government standard that defines a micron rating for an air filter? Please identify it. I'd like to read it.
Beranek's Law:
It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.
Member
A micron rating means nothing without the efficiency at that size. For example polyester felt is rated 99% @ 2.0 micron. PTFE is rated 99.5% @ 0.5 micron. There may be a "micron rating standard" but I'm not aware of one. Most people are interested in performance at 2.5 micron and below for most dust collection applications.
A micron is 1x10-6 meters.
A 10 micron particle is the smallest individual particle that can be seen by the unaided human eye. Human hair is about 70 micron in diameter.
MERV rated filters are primarily for HVAC applications not dust collection. HEPA is 99.97% @ 0.3 micron. MERV 15 is close.
Felted fabrics usually do not need a dust cake to reach their stated efficiencies. Cloth fabrics (think of a tablecloth type material) usually require a dust cake to reach their efficiency.
Filters do have an efficiency curve although not as gradual as a cyclone. A polyester felt that is 99% @ 2 micron will still get some of the 1 micron particles, but a much lower percentage, and it will probably approach 100% @ 3-4 micron.
I hope this helps.
Contributor
I'm not Johnny, nor does he need me to defend him. However, I believe you're misreading him. He's agreeing with you. You started this thread asking what a micron rating means in this context and have pointed out that there's no meaningful standard for the use of such a term. All Johnny was saying is to ignore the 'micron rating' and buy a filter that does meet a regulatory standard.
David Walser
Mesa, Arizona
[OP]
Member
Oh, sorry. I was hoping he might be aware of a spec that had a default efficiency number or something to further define "micron rating". No snark intended.
Beranek's Law:
It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.
Contributor
I believe the purpose of this thread is to sort out whether or not there is an actual formal specification for a 'micron rating' & what it actually is. The problem is that the marketing wanks have way to much free rein in composing product literature & end up creating confusion and mis(dis)information with their made up terms & specs. Correct me if I'm wrong David.
Contributor
I must be having a hard time understanding this subject as I have yet to see anyone come forward with a published definition, specification sheet or other documentation of "micron rating"
Seems like all responses have been personal opinions and no hard factual written information.
Would really like to see something in published writing about "micron rating"
Not trying to be a hard__s, just want to see cold hard facts instead of opinions and marketing fluff about an important matter that effects our personal health.
I work with Merv ratings at primary job and have for last 30 yrs, still waiting on anyone especially the salesmen I have asked to provide the written spec's that define "micron rating"
Get lots of fancy talk with marketing fluff and no hard cold facts.
Ron
Contributor
That's my point exactly.
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