Replies

1. 
   forestgirl | Apr 06, 2008 06:53am | #1

   Doug, there's a parallel thread going here <click>.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 
   
2. 
   GRW | Apr 06, 2008 01:20pm | #2

   I have the Jet. They have a washable prefilter you can buy. You need to ask for it. They would rather have you buy the disposable one many times over. I really like the Jet unit. I have no experiance with other air cleaners.

1. 
   forestgirl | Apr 06, 2008 07:01pm | #3

   "They have a washable prefilter you can buy."  The review I found (Wood, #172) addressed the washable v. disposable prefilter question.  It seems that the washable filters actually let significantly more dust go through to the main bag filter.  A surprise to me, but as expensive as the bag filters are, I'd stick with a disposable prefilter and just tap/blow it out a few times before replacing it.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

   Edited 4/6/2008 12:06 pm by forestgirl

1. 
   GRW | Apr 06, 2008 09:54pm | #4

   FG,I've had my Jet for about 6 years. I've had the washable filter for most of those years. The fine inner filter seems to be as good now as the day I bought it. I expect to get a few more years of use from it. If that filter lasts 6+ and maybe up to 10 years, I'll be happy.My observations (no real data here) is that the washable filter clogs up faster than my old disposable filter. This might imply that the washable filter catches more particles than the disposable filter. All I know is that I haven't bought a filter in years, and my air cleaner seems to work fine in my shop.I don't question the data you have read. I'm sure it's better than my observations. But I have already saved enough $$ (not counting time and shipping cost)to pay for a new fine inner filter. Yet I don't think I'll need one for years. By then I may have saved enough money for a complete new air cleaner.

1. 
   forestgirl | Apr 07, 2008 06:44am | #5

   Does the Jet have a bag filter for the inner filter?  I just checked on the JDS web site to see what the recommendation is for the bag filter in my 750ER, and they say average life is 1.5 years when "used regularly."  A rather loose term "used regularly" LOL.  I'm sure mine will last several years.  Good luck with yours!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

1. 
   GRW | Apr 07, 2008 01:26pm | #6

   FG,

   The Jet has the inner filter. I can't tell you if the Jet is the best air cleaner available. I do know it seems to work in my shop. I have dust collection on most tools. Though my tablesaw DC is only about 50% effective, and I don't have a downdraft table yet. I keep investing in my shop, and dust colection. Recomendations are aways welcome.

    

2. 
   forestgirl | Apr 07, 2008 04:31pm | #7

   What kind of tablesaw do you have, GR?  They are such dust producers! forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

3. 
   GRW | Apr 07, 2008 05:38pm | #8

   FG,

   I have a Powermatic 64A. I have a small Penn State DC with a dust separator under the extension wing. I'm on a slab and don't want 4" hose running across the floor. I have most of the back of the saw blocked off. (75% maybe) I put a 1 micron bag on the DC but it clogs fast, so I went with a 5 micron. I'd like to hook up one of my JDS's with a canister filter to it. I just have to work out how I'll run the hose. I've also been looking for a good DC that can replace the Penn State unit under the TS extension with 1 micron filtration.  No luck yet... Open to ideas....

4. 
   dougmeyer | Apr 07, 2008 07:01pm | #9

   Yeah TS are not good about dust colection. I wanted to put on an overarm gaurd with DC but the cost is just not in the budget at this point.

   Doug

3. 
   HowardAcheson | Apr 07, 2008 07:13pm | #10

   Here's some info that may help as you decide on getting an air filter. It's relevant whether you build one or buy one.

   The two most important criteria for an air cleaner are the CFM and the filters. You want a CFM factor that will clean the size of your shop and a filter that removes the particle size that you are concerned about.

   To determine the size or required air flow, use this formula: Volume of your shop (Length x width x Height) times Number of air changes per hour (typically 6 - 8) divided by 60. This will give you an answer in Cubic Feet per Minute which is how air cleaners are measured. MOST AIR CLEANER MANUFACTURERS RATE THE CFM OF THE FAN ONLY, but there are losses due to the filters. If you are building your own or if the air cleaner you are purchasing rates only the fan, figure you will lose about 25 - 40% for filtering losses.

   As important as the air cleaner size is how and where you mount it. Try to mount at about 8-10 feet above the floor (no lower than 6'or 2/3 of the floor to ceiling distance if less than 8' ceiling). Mount along the longest wall so the intake is approximately 1/3 the distance from the shorter wall. Mount no further than 4-6 inches from the wall.

   The exhaust is the largest determiner of the circulation pattern. You are trying to encourage circulation parallel to the floor/ceiling so ceiling mounting is not recommended. Use a smoke stick (or a cigar) to observe and maximize circulation. Use a secondary fan to direct air to the intake if necessary. Also, consider that a standard 24" floor fan moves a lot of air and, in some shops, just positioning it in a doorway with a window or other door open can accomplish as much or more than an air cleaner. It's all in the circulation patterns.

   The exhaust is the clean air so that is where you want to position yourself. Do not place the air cleaner over the a dust producer. That will guarantee that the operator will be in direct line between the dust producer and the air cleaner. The operator wants to be in the clean air stream. If the dust has to pass your nose to get to the air cleaner, you get no benefits. If you have an odd shaped shop, two smaller units may be better than one large one.

   DO NOT RELY ON A AIR CLEANER TO ACT AS A DUST COLLECTOR. The purpose of and air cleaner is to keep airborne dust in suspension and reduce airborne dust as quickly as possible AFTER THE DUST PRODUCER HAS BEEN TURNED OFF.

   Finally, if you are looking for health benefits, you will not find any air cleaner manufacturer that makes health claims because there are few health benefits. CATCHING DUST AT IT'S SOURCE IS THE BEST LONG TERM GOAL. Rick Peters', author of "Controlling Dust in the Workshop", makes the point that spending your money getting the dust at its source is a better investment than trying to capture it after it is already airborne. If the dust is in the air, it's going to be in your nose and lungs too. Robert Witter of Oneida Air Systems has noted that "overhead cleaners can only lower ambient dust levels AFTER THE SOURCE OF EMISSIONS IS SHUT DOWN, and they take several hours to do this. This is why they are not used in industry." The absolute best answer, if health is the primary concern, is to use a NIOSH approved respirator. The dust cleaner will help keep your shop cleaner but have minimal or no health benefits. OSHA takes this position too. They measure the number of particles per a volume and most air cleaners will not satisfy their specs.

   Howie.........