Replies

1. 
   forestgirl | Sep 13, 2004 11:37pm | #1

   Frank, my main suggestion would be to find and read different reviews before selecting a brand.  They differ greatly in ease of use (read: changing filters), how well the different stages work, and how they perform after the filters are partially covered with incoming dust.

   I lucked out at a summer auction and got an older but un-used JDS system for $85.  Am happy about this, because if memory serves JDS does better in tests than either Jet or Delta.

   I can look tonight for a couple of reviews if you'd like.  Don't be surprised if you get a response that includes the opinion that air filters cause more problems than they solve.  It pops up every time this discussion arises.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
   Another proud member of the  "I Rocked With ToolDoc Club" .... :>) 

2. 
   BArnold | Sep 14, 2004 12:20am | #2

   Mbiker,

   Good idea.  I have one box fan hanging from my garage ceiling with the lower edge pulled back to tilt it a little.  All I have to do is lay a filter as you describe on the plastic grille and it works great.  A frame like you built is just what I need to do with a second fan I move around!

   Bill Arnold - Custom Woodcrafting

   Food for Thought: The Ark was built by amateurs; the Titanic by professionals.

3. 
   knothole | Sep 14, 2004 02:14am | #3

   I made mine from an old air cond. fan. There were plans in one of the woodworking mag's. a few years ago.  Mine uses 20x30 filters and works great. If you can find an old a.c. blower cheap it doesn't cost much to make.

4. 
   RandMCapozzi | Sep 14, 2004 03:41pm | #4

   The Febuary 2002 issue of WOOD Magazine did a comparison test of six air filtration units. This may help you formulate which features you find the most important.

   I believe most of the filtration units are very similar. I happen to have the JDS 750ER. Features I looked for were remote, timer, easy filter access, Filtered CFM ratings (many of the manufactures provided unfiltered CFM which to me is useless since I'm gonna use the unit with the filter in).

   Good luck,
   --Rob

5. 
   nikkiwood | Sep 14, 2004 05:03pm | #5

   Here's the warning that FG was talking about, and it should probably be factored into your decision:

   http://www.oneida-air.com/techarea/health_haz.htm

   Oneida, in case you don't know, is one of the big mfgs of dust collection systems. This piece was written by one of their tech people, and it should be noted that Oneida does not make air cleaners.

1. 
   RandMCapozzi | Sep 14, 2004 07:35pm | #6

   I've seen this article before. While lurking on another WW forum this article was also brought up. Thought I would include two responses from a poster on that forum. I found the responses to be a good counter-point to the article. Hopefully with both sides discussed everyone will be better able to make their own decision on air cleaners in WW environments.  

    

   Response #1

    

   "Before everyone starts trashing their air cleaners I would like to point out a few things in the "article" cited. 1) Oneida is in the Dust Collector business, not the air cleaner business. They want you to buy their expensive dust collection systems rather than an air cleaner. The article is, by definition, biased. 2) The article does not cite a single valid source for its so-called "scientific approach". There is no peer-review, no experiments were conducted and no data were collected. 3) The article does not state what the collection efficiencies were for the air cleaners that it attacked. Most systems now offer 1 micron or even 0.3 micron filters. 4) The article incorrectly states that "It is the 1-10 micron particle size range industrial hygienists consider the most damaging to human health." While this is generally true for most airborne contaminants, the primary threat to woodworkers is naso-pharyngeal cancer. Particles from about 5 to 50 microns deposit in the naso-pharyngeal compartment. There are numerous other inconsistencies in the "article" (diatribe is probably a more appropriate term) that make its conclusions worthless. This is a subject that I know a good deal about. The bottom line is that effective dust collection and air cleaning involves several factors. The primary factor is source reduction. This is done with a dust collector system. However, even an Oneida dust collection system does not collect all dust created by woodworking activities. An ambient air cleaner *will* help remove the remiaining airborne dust. If I get some time, I will cite some peer-reviewed technical journal articles that support my point. They exist and their conclusions are real. Mr. Witter's treatise is a cheap-shot marketing op-ed piece, not a scientific reference. It should be treated as such. "Tim -- Woodnet.net forum

    

    

    

   Response #2: Italics are from a posting another forum made:

    

    

   "I have no intention of trying to change your mind on this issue. However, I do think that it is very important that people who are considering an ambient air cleaner know the actual facts, not some marketing propaganda. So, my remarks are not necessarily argumentative, just illustrative.I don't want to go into how scientific or factual the article is, but it is what it is. I am not sure at all what you mean by "it is what it is". The article "is" neither scientific, nor factual. The author makes several specious points with no basis in fact or scientific principle, yet he claims a "scientific approach". Assuming the 1-10 micron particles pass through the air cleaner, they will remain airborne, and the air cleaner will continue to circulate those particles within your shop over and over again. If you can get these particles out of the air, than you should do it. There are several severe flaws with this argument. First, your initial assumption is false, which pretty much blows the rest of the argument. Most air cleaners have an efficiency of at least 85% for 1 micron particles, and efficiencies approaching 100% for 10 micron particles. This is well documented. Therefore, your assumption that "1-10 micron particles pass through the air cleaner" is false. You also said that the air cleaner will continue to circulate the particles over and over again. It is probably important at this point to understand a little bit about small particle aerodynamics. A 10 micron particle of wood (assuming a density of 700 kg/m^3 and typical values for air density and viscosity) has a settling velocity of about 2 mm/sec. A 1 micron particle has a settling velocity of about 0.02 mm/sec. The 10 micron particles will eventually settle in still air (after about about an hour for a height of 6 feet), but shop air is never still. A good guess is a settling time of 2 to 3 hours for a shop with some HVAC air movement and casual people movement. For 1 micron particles, the settling velocity is so low that they essentially act as a gas and for the time frames of concern (hours) they never settle. As a result, particles 1 to 10 microns in mean aerodynamic diameter essentially never settle for a typical shop session. This would be true whether there is air stirring (by an air cleaner for example) or not. So, while it is true that an air cleaner that was transparent (not correct as I have shown) to particles of this size would redistribute them, they would remain airborne anyway. So, the argument that an air cleaner would redistribute these particles has no merit.Now instead of blowing air, I will be sucking air. I assume by this that you mean you are using a dust collection system. Let me just point out that they suck *and* blow. Furthermore, while air cleaner filters are typically efficient at collecting dust particles in the 1 to 10 micron range, most DC bags are pretty much completely transparent to particles under 30 microns. What these systems do is collect most of the dust from the source, trap the big particles, and spew the small particles into the air. This is in contrast to air cleaners, which do not add anything to the airborne dust load, but only serve to reduce it. If you are only relying on your DC, you should be using upgraded bags that filter to 1 micron or better. Just to summarize (since I tend to get a bit wordy on these issues), the article is specious for the following reasons (among many):1) It assumes that ambient air cleaners have zero collection efficiency in the 1 to 10 micron range. In actuality, most units are at least 85% efficient for those particles - meaning that they will remove 85% of the particles that enter them.2) It assumes that ambient air cleaners contribute to the redistribution and resuspension of small particles. This is incorrect. Particles this small will remain suspended for many hours regardless of whether the air is stirred or not. The physics of this is undeniable. I suppose one could argue that if the exhaust vent is directed at dusty surfaces, the air movement could stir up particles that have already settled. However, if the unit is placed properly, this should not be a problem. Moving about the shop would tend to stir up much more dust than air movement, and if you use an air cleaner, there would be much less dust to stir.Ambient air cleaners can be an important part of dust mitigation. However, it should not be relied upon as the only means of dust control. A good DC system (with a 1 or 0.3 micron bag) combined with an air cleaner can dramatically reduce the amount of airborne dust in a shop. "Tim -- Woodnet.net forum

    

    

   --Rob

1. 
   Teddy523 | Sep 14, 2004 09:09pm | #7

   Thanks to all on their feedback on air cleaners.  From what I've read hear I've decided to go with the shop built scrubber designed & kindly provided by Dan Kornfeld, imporve my initial dust and chip collection & start using a fan when weather permits.

1. 
   chillywilly | Sep 14, 2004 09:57pm | #8

   I built Dan's model about six months ago and love it! 

   On occasion, I like to have a cigar in the shop.  The air scrubber makes a world of difference in removing that post-cigar stench.

1. 
   Teddy523 | Sep 15, 2004 06:46am | #9

   Thanks Ron.  I acutally found a old blower unit today for 10 bucks so I guess I'm set.  I like to have more than an occasional cigar in the shop, so it's good to hear it deodorizes as well.

   Teddy

2. 
   forestgirl | Sep 15, 2004 06:50pm | #12

   I was just thumbing through the Penn State catalog and noticed they sell electrostatic "smoke filters" -- just for you?  Too funny.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the  "I Rocked With ToolDoc Club" .... :>) 

2. 
   nikkiwood | Sep 15, 2004 10:17am | #10

   Thanks for posting these responses to the Oneida article.

   I am in no position to judge the "science" of all this. But three things struck me here.

   One guy claims that Oneida is biased because they are in the dust collector business. He fails to understand that no one (not even the manufacturers) claim that an air cleaner might be used in place of a DC. Furthermore, it was my interpretation that if Oneida wanted to produce a line of air cleaners, they certainly have the capability of doing so. They also have the brand name that could give such air cleaners a real marketing punch.

   Second, the Oneida piece claims that air cleaners cause more dust to be suspended in the air as they do their work. In my own shop, I could witness this phenomenon; as a consequence, I put the air cleaner on a timer, and turn it on when I leave the shop area.

   Finally, one of the problems of these anonymous internet forums is that we usually don't know anything about the credentials or biases of the respondents. The remarks here sound suspiciously like the words one would hear from a marketing person from one of the air cleaner companies.

   Even around Knots, I occasionally pick up the whiff of a company man touting the virtues of his product. I am not bothered by this, if indeed it does happen, but it does seem prudent to maintain a healthy sense of skepticism as we process the information brought to these threads.

1. 
   RandMCapozzi | Sep 15, 2004 03:54pm | #11

   Yes. I've witnessed this "marketing" bent to responses as well. I don't have anyway of verifying the qualifications or intentions of the responder nor do I have anyway to verify the qualifications or true intentions of the "Oneida" article. What I did find compelling (made sense to me as a layman in particulate aerodynamics) was the response to the article's main claim that air cleaners simple continue to distribute particules.

   "[The Oneida article] assumes that ambient air cleaners contribute to the redistribution and resuspension of small particles. This is incorrect. Particles this small will remain suspended for many hours regardless of whether the air is stirred or not. The physics of this is undeniable. I suppose one could argue that if the exhaust vent is directed at dusty surfaces, the air movement could stir up particles that have already settled. However, if the unit is placed properly, this should not be a problem. Moving about the shop would tend to stir up much more dust than air movement, and if you use an air cleaner, there would be much less dust to stir."

   I too can attest to this. I am able to continue to see dust floating in the air regardless of whether the filter is on or not. In fact the smell of dust lingers far longer in the shop when I have the air cleaner off versus when I leave the air cleaner running while I'm in the shop.

   My belief is therefore that a DC (capturing dust at the point of production) should be the primary form of dust control in a WW environment. Air filters are capable of helping (not hurting) control the dust levels when positioned correctly and can be run while you are in the shop without increasing your danger to dust exposure.

   --Rob