Is Air Filtration with .3 micron Hepa Filters possible without spending thousands?

[ed mendenhall]

Does anybody have any experience or knowledge of using hepa filters in a typical small shop air cleaner such as the jds, delta, jet, etc?

I've been doing a lot of research but just getting more confused, (same for dust collection) so I figured I would just ask directly.

The best I've seen mentioned was 1 micron at the inner filter, but most agree that .3 microns is where it's at for lung health. I can't afford to spend thousands on an industrial hepa unit for the basement. So far the only reasonable one is made by grizzly for $589 with shipping. http://www.grizzly.com/products/Larg...r-Filter/G0573 They also carry a Shop Fox fine air unit but it is only 200cfm. I've seen them for $99.

Would it do any good to buy a regular unit (1 micron) and add the Shop Fox for the really fines for a total of around $350-$400?

Or should I just build my own using hepa filters? Anyone seen or built their own? BTW, I plan to install Pentz style Cyclone as well.

Thanks,
Ed

[Kent Chasson]

If your goal is to reduce the number of small particles that you breath, I would suggest you forget the air cleaner and use that extra money and time on your dust collection (or just wear a respirator). In my experience, once the small particles get in the air, an air cleaner will never collect a high percentage of them. They filter the air close by quite well but the fan tends to spread the rest of the particles all over the shop and a lot of dust eventually settles out only to get kicked up again later. It's possible they will actually be harmful because they can make the air feel cleaner and you less likely to wear a respirator even though there are a lot of small, harmful particles still floating around.

Keeping small particles out of the air is no small task. I just spent several thousand dollars and a solid month putting new dust collection in a 600 sq ft shop and I'm still not finished. I am now able to use many of the tools without wearing a respirator but even with consistent effort and patience, I still end up wearing a respirator half the time. If I get it down to 20%, I'll be thrilled.

[David Hostetler]

filter efficiencies are a tough nut to crack for sure. For example the Wynn 35A Spun Bond cartridge filter for single stage dust collectors is rated at 1 micron, but if you look at the MERV rating, it is a higher MERV rating than the .5 micron rated paper blend model... Why is that? Part of it has to do with the testing methodology, and certification process for various filtration media.

If you are truly concerned with HEPA filtration, you might want to contact Dick Wynn and Wynn Environmental directly. Dick has worked with Bill Pentz in the area of woodworking filtration, and is a veritable library of knowledge on the subject.

Generally speaking though, your 1 micron rated filter captures 97+% of all particles 1 micron and larger, they also typically capture somewhere in the high 80% range of particles .3 to 1 microns... Combined with the multiple changes of air in a given volume, and while you will never, not even with HEPA get completely 100% particle filtration, you will get as close as you can...

Mind you, that air filter is not to be used while you are in the shop. That is NOT what they are for. They are there to clean the air AFTER you are done working, so that the next time you enter the shop, you are entering clean air... If you are worried about while you are in the shop, capture the dust before it gets airborne with a proper dust collection system, including proper separation, and filtration.... Again read Bill Pentz' work on the subject. While the subject is deep enough, and Bill goes all the way into it, so there is enough there to melt a brain surgeon's head, if you take your time and digest it bit by bit, his ideas for the most part are dead on...

[Van Huskey]

Mind you, that air filter is not to be used while you are in the shop. That is NOT what they are for. They are there to clean the air AFTER you are done working, so that the next time you enter the shop, you are entering clean air...

Although, they certainly aren't the first line of protection (removal as close to the source is) I have never heard they were not for use DURING work. The manufacturers certainly market them as such and the magazine articles testing them assume they are being used while working. It seems very odd not to use them the entire time you are in the shop. Most are designed with a timer to continue to scrub the air after you leave but I am still at a loss to understand the logic of not running them when you are in the shop, please illuminate me.

[David Hostetler]

Think about it, if you are producing dust around waist level, and you are pulling that dusty air up to ceiling level to get to the filter, what does it have to pass? Your mouth and nose. Also the air movement tends to kick up dust that has settled in the shop....Both the Wood Whisperer and Fine Woodworking had videos on the subject a few years ago... Check out The Wood Whisperer videos for video #88 I believe it was...

Having said that, I tend to run mine prior to my entry into the shop, while I work and afterwards... I know I am not supposed to while I work, but it helps keep the air in my shop cooler, and it REALLY helps the A/C move the cooled air around my shop! I don't know that it is THAT much of a danger, but if you are going to be ultra paranoid about dust, then best to avoid it as much as possible... I am trying to take the as good as possible while staying sane approach... I don't think the last bit is working too well though.

[Van Huskey]

Think about it, if you are producing dust around waist level, and you are pulling that dusty air up to ceiling level to get to the filter, what does it have to pass? Your mouth and nose. Also the air movement tends to kick up dust that has settled in the shop....Both the Wood Whisperer and Fine Woodworking had videos on the subject a few years ago... Check out The Wood Whisperer videos for video #88 I believe it was...

Having said that, I tend to run mine prior to my entry into the shop, while I work and afterwards... I know I am not supposed to while I work, but it helps keep the air in my shop cooler, and it REALLY helps the A/C move the cooled air around my shop! I don't know that it is THAT much of a danger, but if you are going to be ultra paranoid about dust, then best to avoid it as much as possible... I am trying to take the as good as possible while staying sane approach... I don't think the last bit is working too well though.

I think you are mis-applying the theory. The problem with the really harmful sized particles is that they stay in suspension in the air even with little to no air movement. I think what Marc was trying to say is it does not negate the need for a respirator. I am open to others input but my firm belief is that on balance the air cleaners make the workshop better for your lungs on a whole by running them while you work and after compared to JUST running them after. The harmful particle sizes just don't settle and ANY air movement in the shop are going to keep a significant amount of them in suspension at nose level. Take a look around after a long ROS sanding session and you will see the amount of VISIBLE particles in suspension at well above nose level, if these large particles are in suspension you can guarantee the small ones are as well in an even bigger percentage. These filters work and in my opinion not running them while you work is reducing their efficacy and increasing the particle load on your longs both small and large. In the end capture all the dust you can at the source (and make sure you are not reintroducing it) but no matter how effective this is it isn't 100% on any tool/DC system I have seen, you still have to treat the ambient air.

[David Hostetler]

I won't argue with you on that, I run mine while I work and had assumed I was doing something bad... But I figure it swaps the air how fast? And honestly, I won't get anything done if I am sweating to death in there...

So I guess I can stop feeling stupid about using my air filter while I work then?

[Van Huskey]

So I guess I can stop feeling stupid about using my air filter while I work then?

I would! If you look at the recent I think FWW test of these (where I think the Jet won) they showed the times it took each of these to reduce the fine particle size by some percentage, I don't remember the exact time periods but they were far shorter than my typical shop time. I think running them while you work is good, but assuming they keep the air 100% safe all the time is the bad idea since they don't and even if they make it WORSE for a short time (I am not sure about that given the particle size we are concerned with) on the whole they make the air safer.

[Van Huskey]

BTW this rewritten article may shed some light for the OP and others:

http://www.finewoodworking.com/fwnpdfFREE/011213054.pdf

[phil harold]

I think the OP is concerned about creating dust in his house
Shop is in the basement and will migrate into the rest of the house
I would consider venting the Pentz style Cyclone outdoors
Just need to make sure if you are pumping air out of the house with the cyclone you need to have a source of make-up air

[Carl Babel]

I strap a Filtrete Ultimate filter onto a box fan, set it next to where I am working, and work away.
This is in addition to my DC system (Oneida).

[Neil Brooks]

I strap a Filtrete Ultimate filter onto a box fan, set it next to where I am working, and work away.
This is in addition to my DC system (Oneida).

Me, too.

Lots of "us," actually, from what I've seen.

In my case, I actually go one step farther. My whole-house air cleaner uses a 5" thick pleated media filter:



It gets sandwiched on there, too, along with the Filtrete, and sits on my sanding table, while I'm sanding. It's also on a cheap Harbor Freight programmable timer, and runs, on "HI," about 3hrs, in the middle of the night.

AND ... a hanging JDS unit, and a pretty effective DC, AND ... one of these jobbies in my shop window:



But ... because I just enjoy this DC stuff ... I picked up a used bomb-proof fan, for a hundred bucks, and am building a 30 x 30 x 30" rolling air filtration cube that will use one 5" pleated media filter, and TWO 3M Filtrete filters.

I'll install a threaded insert into the top panel, so I can add or remove a big eye hook, and hoist it into the air, by pulley on the joists, if necessary.

I'm using a 12-hr attic-fan timer, with a "hold" feature, as the switch.

I do NOT aim for an ISO 14644-1 cleanroom (), but ... my shop's in the basement, and want to do what I can to keep the mess at bay.

[ed mendenhall]

Hey everyone, sorry it took so long to chime in but I must have missed the check box to get email notifications for replies. I have been checking my email every few hrs with no responses (feel like an idiot) so I checked into the forum tonight. Glad I did....

Let me clarify a bit... I am setting up my first workshop in the basement. I do intend to go all out with the "Bill Pentz" style cyclone system. So i hope to catch most at the source. Of course with the expense and work involved it will be a while before it is complete. (Not to mention the research, after reading Bill's site, my head is spinning....)

Anyway, from what I read people tend to agree that fine dust under 1 micron is the true danger. However, with all of the popular ambient air filtration units out there, there doesn't seem to be any that address or offer filtration at that level. (at least not at the "hobbyist" or under $2k level) So for the not so wealthy people like myself who want to protect our lungs including a good cyclone system what do we do?

Is it possible to find a hepa filter that will fit into an existing, name brand unit, or are we stuck making our own. I know it is usually less expensive to make our own, but I don't want to spend a year building all my own safety equipment (Cyclone, air filter, downdraft stations, etc) before even starting the actual wood working projects. It would be nice to buy a $300 name brand unit and fit hepa filters.

That is my first priority to sort through, then it looks like a few other good points were brought up as well. When do you run the air filters? How about the performance difference between ceiling mounted and floor units.

David, I will try contacting people at Wynn, thanks. I'm surprised with all the wonderful work Bill Pentz has done with cyclone design that he didn't design a great air filtration unit to go with it...hmm just a thought, I'm sure he is busy though, I think He mentioned helping out his son with the business.

Sorry to be so long winded I'm off to check out the fine woodworking article. Thanks Van.


Ed

[Rod Nikkel]

Generally speaking though, your 1 micron rated filter captures 97+% of all particles 1 micron and larger, they also typically capture somewhere in the high 80% range of particles .3 to 1 microns...

Not really. It will capture 97+% by weight, but not particle numbers, right off the bat. That means that, according to this graph on the Wynn site itself, http://www.wynnenv.com/filter_efficiency.htm less that 1/2 the 1 micron dust gets caught and less than 1/3rd of the .3 micron dust is trapped. Most goes right through till the filters have enough dust in them that the dust cake makes them more efficient at trapping particles, but less efficient at letting the air through. Here's what a few hours of research, including talking to the technical people at the filter companies, taught me. http://www.sawmillcreek.org/showthre...and-don-t-mean) If you really want to start off with clean air through the filters, you have to go at least MERV 16.

[phil harold]

Bill Pentz recommends exhausting the cyclone to the outside
this will eliminate the fines being recirculated in the structure