MERV 16 (or HEPA) Air Scrubber/ Filtration

[Peter Aeschliman]

Hi guys,

I'm trying to improve the quality of the air in my shop. I've noticed that I get a sort of tightness in my chest just behind/below my sternum after a day of working in my shop. I have a plan for upgrading my dust collection, so now I'm turning my attention to air filtration.

I have a Jet 1000B air filtration unit, but I now know that it's basically worthless for collecting the most harmful particles (less than 1 micron).

I would like to make my own air filtration units, using two filters each (outer filter for the big stuff, inner filter for the fine stuff). I'd like for the inner filter to be MERV 16, which I understand to be as close to HEPA as I can get. My concern is that the finer filter will cut down air flow too much. My shop is about 450 SQFT with 8' ceilings. The floor plan is close to square, with no solid walls in the middle.

So now, my questions... drum roll please.

What kind of blower is recommended given my MERV 16 requirement and my shop size? Meaning, how much CFM, HP, etc do I need to overcome the filter resistance, without damaging the filter media?
How many filtration units are adequate to create the proper circulation path for the air (I understand you want the air to move in a circle around the shop)?
How much filter media surface area is recommended?
What outer filter should I use? MERV 8 outer filter?


Now let me preemptively rule some things out for you guys so that we can focus on the question at hand:



Yes, I know that the best method for reducing airborne dust is to collect it at the source.
Yes, I know that air filtration units are only a last resort, and that they can have a tendency to stir up existing dust. My goal is to collect dust at the source as much as humanly possible, and catch anything that escapes via my air filtration units, so that it doesn't have time to settle and be stirred up the next time I'm in the shop.
I also know that it can tend to pull new dust (as you're making it) up toward the ceiling and thus up in front of your mouth. To me, this comes down to being smart about where you position the inlets in the shop, and if necessary, wearing a respirator while performing those tasks. But I'm not going to turn the air filtration off during those tasks only to let the dust stay suspended in the air and later settle, only to be stirred up later. Seems like cutting off your nose to spite your face.
Yes, I have read Bill Pentz's website. I have a 3HP 4-bag dust collector, with integrated Thien baffles and two huge Wynn Environmental Poly-spun (or whatever they're called) filters. The thing still leaks a lot especially around the bag clamps... and emptying the plastic bags is not fun. So, I have ordered one of the Ebay cyclones (seller name is eastcaroga- nice guy), and plan to use my 3HP motor and impeller with it, and to vent outside.

Yes, I know, it will suck the heat outside- I'm willing to make the trade off
It's a stand-alone shop, so I don't have to worry about furnaces/etc
Yes, I know, I need a gazzillion HP motor and a giant impeller, to do it right but I'm trying to save some money by using the motor and impeller I already have.
Yes, I know the Pentz design will separate the dust better, but I'm not concerned about protecting the filter since I'll be venting outside
No, I don't have nearby neighbors


I have ordered a dust deputy and have a plan for redoing my shop vac setup to capture that dust- it's also a problem for me today
I have plumbed the shop with 6" ducting.
Yes, I have searched on this topic. There very well might be a thread I missed that answers this, so please feel free to include it here!


Please, don't bring any of the above items up- I would really like us to focus on my question! I've read a lot of threads where people ask this kind of question, the thread gets overwhelmed with responses about the items above, and the question never ultimately gets answered.

Thanks in advance!!

Peter

[Alan Lightstone]

Peter:

I'm not sure why you are dismissing the Jet 1000B. I use it, and it dramatically reduces the particle count of 0.5 micron particles (if you can believe my Dylos particle counter). If a MERV 16 filter reduces its flow, wouldn't that just mean that it takes longer for every air exchange in the room (less per hour). Not optimal # of air exchanges per hour, perhaps, but still doing something.

BTW, I have to check, but I think I have been using a MERV 15 outer filter on mine. I do have a 5HP Oneida cyclone, though, but no lack of airborne particles with belt sander or table saw.

[Peter Aeschliman]

I certainly can't argue with Dylos readings- I'm making the assumption that it's inadequate since it's rated only rated for 85% efficiency for 1 micron or larger. I have no idea what it does for particles smaller than 1 micron, but I assumed it was far less efficient in that range.

But with a MERV 16 from what I read online, you can get 75% or better in the .3 to 1 micron range. With the ratings of the 1000B, it's probably in the range of MERV 12 or so.

It's definitely better than not having one at all, but I was hoping I could do better than that with a home-built unit.

[ian maybury]

Not 100% sure what's around in the US now, and what the makers are claiming re. full HEPA filters - until recently at least it seemed like properly certified items were not readily available.

Pressure drop won't be a problem provided you install enough filter area. Sizing/square footage will be determined by the rate of recirculation of air you decide you want - but that's a bit of a double edged sword by all accounts in that if you get into high enough airflows you may also (at least temporarily) raise a lot of dust in the workshop. Effective diffusion may be important. i.e. exhausting through a bag or something over a large area so that it wouldn't create draughts.

The other issue though is that if too much fine dust is making it into the air (whatever about the effect on your lungs) because your at source dust collection system is not working very well the filters may blind up too quickly. i.e. effective at source collection is going to matter anyway.

I don't think you're going to get anybody providing genuinely definitive information for a system along the lines you are thinking of - in that even if the work has been done, and even if an effective system can be achieved via this route it doesn't seem widely published or used. There may just be a reason for this....

The other way of looking at it is that experience says that a high CFM Pentz style dust collection system seems to work pretty well as an air cleaner anyway - whether it does so by drawing in fresh air to replace that which has been exhausted, or recirculates it through a set of high quality filters. (they are easily set up so that both options are available by opening a blast gate) In a smaller workshop like i have anyway....

If you're already on the DIY road to build some sort of super air cleaner, and already committed to reworking the dust collection system by buying a cyclone to drop out chips before exhuasting the rest, and are going to need/already have properly sized ducting to get effective at source collection then maybe there's no reason why you shouldn't alternatively and for similar input build a Pentz style system - it'd only require buying a 16in Clear Vue impeller and motor to suit... (the rest can be built DIY as i did)

Which if true would bring it down to the question of which solution is likely to deliver the best results in terms of air quality and serviceability...

ian

[Jeff Duncan]

OK I know this is not exactly what you want so I'll apologize ahead of time, but some things to consider...

First, it's impossible to collect all the dust at the source, even if you have brand spanking new top of the line Euro equipment there's still going to be dust that escapes, so your right about looking to improve your air filtration. I don't know the practicality of filtering out to sub 1 micron so I'll leave that to the engineers. In fact you may want to track down an HVAC forum to ask your specific question on matching motor/fan size to Merv rating and filter area?

Second, if you feel your having some health issues related to dust now is the time to make changes before it gets worse. Optimizing your dust collection and air filtration are good steps. Another thing to think about is the types of wood you work with. If your one of those guys who loves working with exotics, you may have to reconsider. Exotics generally speaking are especially toxic for us to breathe and you'll probably want to avoid them. Other woods like cedars can also be irritating to the lungs. Many domestic hardwoods like maple, poplar, and oak are less irritating to work with.

good luck,
JeffD

[Kelly Colin Mark]

I bought a used Abatement Technologies Predator 600 air scrubber from my local Craigslist/Kijiji. It's used for containment in construction, is built like a tank, easily moved around, very quiet compared to my Steel City overhead filter I have at my cottage, has a HEPA filter and most importantly does an incredible job of reducing fine dust particles as measured by my Dylos.

I was a little worried that it would be too small for my very small shop, but it does a good job.

[David Kumm]

I would buy a good face mask for sanding as that is when the fine dust will overpower the scrubber, and buy MERV 14 inner filters for the overhead. You are filtering the shop air every 4 minutes so the submicron stuff will be passing through quickly enough that even if the filter is only 33% efficient it will clean up the air in a few passes. All the other air you breathe won't be filtered as well as the shop. Dave

[Peter Aeschliman]

Thanks everyone for the replies.

I have a P100 dust mask as well.

I like the idea of diffusing the exhaust.

I know that Merv 16 units exist, so maybe the best way for me to figure this out is to reverse engineer another unit.

[michael osadchuk]

Consider getting a Dylos .5/2.5 micron calibrated particle counter to get some empirically based information on what is working and what isn't .... perhaps have it in place after you do the cyclone/venting of the 'fines' outside and improving on the shop vac projects and before committing to the diy overhead dust filtration unit.......

about generating an air flow/circulation pattern to better convey fine particles to an overhead air filtration unit..... as far as I've read in the woodworking forums (and what you have doubtlessly read) two units seems to be recommended..... but I don't see why, as a stop gap measure one of these units couldn't a cheap 20" square box fan (with or without filters) to help create that circulation pattern.... I've read about the use of 'smoke' sticks to visually confirm the existence of such circulation.....

....another thought..... add some merv 14 or 16 filter material behind the current filtering media of your Jet.... don't know how much this would affect output flow, etc. but with a Dylos counter you would be able to assess the effect of this (or other changes)

good luck

michael

[Peter Aeschliman]

Consider getting a Dylos .5/2.5 micron calibrated particle counter to get some empirically based information on what is working and what isn't .... perhaps have it in place after you do the cyclone/venting of the 'fines' outside and improving on the shop vac projects and before committing to the diy overhead dust filtration unit.......

about generating an air flow/circulation pattern to better convey fine particles to an overhead air filtration unit..... as far as I've read in the woodworking forums (and what you have doubtlessly read) two units seems to be recommended..... but I don't see why, as a stop gap measure one of these units couldn't a cheap 20" square box fan (with or without filters) to help create that circulation pattern.... I've read about the use of 'smoke' sticks to visually confirm the existence of such circulation.....

....another thought..... add some merv 14 or 16 filter material behind the current filtering media of your Jet.... don't know how much this would affect output flow, etc. but with a Dylos counter you would be able to assess the effect of this (or other changes)

good luck

michael

That's very sound advice. As an analyst by trade, your approach makes lots of sense! I'll see about ordering a dylos.

[Lornie McCullough]

Hi Peter

I enjoyed the specificity of your question. If I didn't already have four of the pictured units, I would build them.

(first) I would go to my favorite filter supplier, and buy the largest, most common, best value MERV 16 filters they stocked. Then buy MERV 8 filters, and also some bulk filter material that I could custom cut myself.

(second) I would source the largest, most common, best value, 'used' if I could find them, HVAC squirrel cage fans I could get.

(third) Build an open-ended plywood box sized to hold the squirrel cage fan, and the generic (non-proprietary) filters stacked in each end of the box.

(fourth) Mount them at the ceiling arranged to blow the air in a circular pattern.

(fifth) Add an inexpensive ($10) wireless remote controller to each unit.

260798

I accept that I make a lot of dust that will never be captured by my cyclone dust extraction system. I too can feel 'consequences' after working all day in a less-than-perfect dust-free shop. And I know that sweeping raises all kinds of dust that cannot be seen. What I have described here is the best-value non-proprietary system I can imagine. Please share any improvements you can make.

Lornie

[Jim German]

First thing I would do is get a particle counter, you may find that with the cyclone dumping outside you're circulating enough air through the shop you don't need anything else. With a 3HP DC in a fairly small shop you're going to be emptying all the air in 3600 cubic foot shop pretty darn frequently. As long as you are pulling 'clean' air in in such a way that you get decent circulation, you may very well not need anything else.

That being said, if you still do need further filtration, you could probably get away with modifying the Jet to accept a higher quality two stage filtration system.

Also, just saying Merv 16 doesn't really matter. The real question is what is the overall pressure drop of the filter(s) You can have a Merv 16 filter with a lower pressure drop than a Merv 14 filter. (for instance if the Merv16 has significantly more filter area). More filter area is almost always better (up to a point at least) but more filter area takes up more room and costs more.

Merv 8 is typical of a pre-filter.

[Julie Moriarty]

Before I retired I was talking to some HVAC guys on the jobsite about shop air filtration. That's when I first learned about MERV and HEPA. Their recommendation was to start with a furnace rated squirrel-cage fan, since MERV 12 and over filters are often used with these fans. They then recommended as large a surface area I could create, given the dusty conditions, and placing a cheap filter in front of the HEPA filter. But static air pockets within the shop would not be affected by anything I built or bought so I would have to create an air flow within the shop that would ultimately direct the dust into the air filtration unit.

By the time we were done talking about it, I realized that any thoughts of an air filtration unit keeping me from breathing in dust was a dream. While I'm standing there creating dust, by the time that dust made it to the ceiling mounted air filtration unit, I would have inhaled just as much dust as if the filtration unit wasn't there.

A couple of months ago I took two box fans and built boxes on them on the intake side for (1) 5"x20"x20" MERV 13 filter and (1) 1"x20"x20" cheap filter. If I'm sanding at the workbench, I can place one fan blowing into the sander and one on the other side blowing away. Filtered air comes in across the workbench and pushes the dusty air into the second fan filter. I was surprised how much dust it captured, and I was using a Festool RO sander connected to a Festool dust vac.

I take those fans and I place them where they do the most good, wherever the most dust is being spewed out. And when I'm done, I set them up to move air around the shop while I'm gone. When I return, it's as if I can smell the clean air. And the dust that used to make it into the rest of the house seems noticeably absent. Even with all this, I still wear a dust mask, because nothing is perfect.

[Peter Aeschliman]

Thanks again everyone for your responses.

Lornie, ideally I'd do exactly as you've said. From some very light research, I'm finding it difficult to locate a squirrel cage blower with enough CFM at a reasonable price. At the prices I'm seeing, it would be just as expensive to buy a new air scrubber and take it apart. I haven't tried calling any furnace installer companies to see if they'd sell me any used ones, though.

Jim, I think it does make sense to start with a dylos after I finish my cyclone setup, and then see what happens. As for modifying my existing unit (Jet 1000B), Wynn Environmental does sell better filters for them... but they only go to MERV 14. It's definitely better than nothing, and this might be because MERV 16 would be too restrictive. I might call Mr. Wynn to discuss.

Julie, you raise good points. The concern that ceiling-mounted units will pull the dust past my face is fair. My plan for this is to position the exhaust of one of my ceiling units such that it blows across my assembly table. I'm thinking that I would use an exhaust duct that directs the air at a slight downward angle across the table where I do my sanding. To Jim's and Michael's points, it makes sense to start with my DC and shop vac upgrades, get a Dylos, and measure results. If I find that my .5 micron particle count reaches dangerous levels while sanding, then I'll need to come up with a solution. Your solution of using fans on either side of the workpiece makes a lot of sense- I would prefer to avoid dealing with that setup and the storage space required for the fans, but it might be worth the trade off to protect my lungs.

What I don't want to do is turn the air scrubbers off while sanding. This would allow the fine particles to get suspended in the air, and perhaps settle in the shop, only to get stirred up and breathed in later. So if it came down to it, I'd rather wear my P100 respirator and run the air scrubbers while sanding. But I think the dylos would help take the guesswork out of the whole thing.

[Jery Madigan]

Bill Pentz has a plan for one. Looks simple to put together and cost is about the same as the jest with much larger filter area. I already bought the blower on ebay and I will be ordering the filter in the next few days. pm for detail if interested.

http://billpentz.com/woodworking/cyclone/air_cleaner.cfm

[Peter Aeschliman]

Now that is awesome. I already have two big Wynn Environmental filters that won't have a purpose for after I start venting my DC outside. I was wondering what I was going to do with them. This might be the ticket, and it will involve far less work to build.

I also like that the air flow isn't as direct on the inlet side with a round filter. With two of these suckers, and maybe a few well-placed fans in the shop to direct the air toward them, I might be in luck.

Thanks for pointing that out, Jery! I've spent a lot of time on Bill Pentz's site, but I didn't see that.

[Phil Thien]

Now that is awesome. I already have two big Wynn Environmental filters that won't have a purpose for after I start venting my DC outside. I was wondering what I was going to do with them. This might be the ticket, and it will involve far less work to build.


Just make sure the airflow wouldn't reverse in the new application.

You don't want the blower pulling from the dirty side.

[Peter Aeschliman]

Yeah, good point. I was thinking about that- currently the dust accumulates on the inside of the filters as configured on my DC. If I go Bill's route and pull the air through the filter, I'll be sucking the dust from the previous setup out of the filter and into the shop... So I'll have to push the air into the filters I guess. Or wash the filters out really well... I bought the washable kind.

[David Kumm]

Filters are made to filter either from outside in or inside out and can't necessarily be reversed so find that out. Cartridge filters were originally designed as outside in and it is only recently that companies have used them inside out. Even if designed that way they aren't as easily cleaned. The dylos will really give you great info as to air quality and to some extent change the way you think about MERV ratings and airflow. They also give you an excuse to never sweep the floor. Those numbers are scary. Dave

[Steve Milito]

Hi guys,

I'm trying to improve the quality of the air in my shop. I've noticed that I get a sort of tightness in my chest just behind/below my sternum after a day of working in my shop. I have a plan for upgrading my dust collection, so now I'm turning my attention to air filtration.



Maybe what you really need is a stress test . . .

[Peter Aeschliman]

You mean a cardio stress test, or a test of emotional stress?? ;-) My cholesterol and blood pressure are all normal, so I'm confident it's related to wood dust.

The tightness I refer to only lasts for 4-5 hours after I'm in the shop... accompanied with very slight shortness of breath. The signs are pretty minor at this point, but I do notice them. They got particularly bad after I tried using some new plastic bags on my DC that were over-sized. I've been using them for about a month and a half. They leak like crazy, and every time I run the DC I start to feel it. Hence this round of changes.

It made me realize that I won't be doing this hobby for much longer if i don't think long term and get my air quality sorted out. I'm only 32 years old, and I want to keep doing this hobby until I'm pushing around a walker! ;-)

[Peter Aeschliman]

Filters are made to filter either from outside in or inside out and can't necessarily be reversed so find that out. Cartridge filters were originally designed as outside in and it is only recently that companies have used them inside out. Even if designed that way they aren't as easily cleaned. The dylos will really give you great info as to air quality and to some extent change the way you think about MERV ratings and airflow. They also give you an excuse to never sweep the floor. Those numbers are scary. Dave

Good to know. I'll just assume the flow direction needs to go inside out, since that's what Wynn designed them for. Right now I'm also glad that I sprung for the washable filters.

[ian maybury]

I'd not noticed Bill's piece on using a cartridge filter as an air cleaner. It's a nice set up - minimal space is taken up. Depending on what the numbers look like you could consider running two cartridges stacked on top of each other to minimise pressure drop and slow the build up of dust.

One advantage if you can find suitable filters and run the airflow from the inside to the outside of the filter is that it would be about as effective a diffuser as you can imagine. Presuming a decent fan you'll get a strong draught if you exhaust the fan through say an elbow.

The in line fan is a neat idea too, but axial flow fans don't make much by way of pressure compared to say a BC radial as used on dust systems, so it'd be worth digging out filter manufacturer's data to make sure that the pressure drop the filters will deliver in use (including when a bit dirty) will be comfortable within the pressure capability of the fan...

ian

[michael osadchuk]

You mean a cardio stress test, or a test of emotional stress?? ;-) My cholesterol and blood pressure are all normal, so I'm confident it's related to wood dust.

The tightness I refer to only lasts for 4-5 hours after I'm in the shop... accompanied with very slight shortness of breath. The signs are pretty minor at this point, but I do notice them. They got particularly bad after I tried using some new plastic bags on my DC that were over-sized. I've been using them for about a month and a half. They leak like crazy, and every time I run the DC I start to feel it. Hence this round of changes.

It made me realize that I won't be doing this hobby for much longer if i don't think long term and get my air quality sorted out. I'm only 32 years old, and I want to keep doing this hobby until I'm pushing around a walker! ;-)

Peter,

I'm not a doctor..... but it sounds from the above that your immune system has been comprised.....

the bad news is, of course, if this is the case, that it could get worse if you don't track down what is attacking it and deal with the 'triggers'; you may have to give up or significantly modify activities you enjoy like woodworking....

the good news is that you can recover some or most of the losses to your immune system, etc.

ironically, another small piece of the good news is that given that your body appears to be 'sensitized' to the triggers that are affecting your breathing, to an extent your body can act as a dust particle counter/monitor ........ you already seem to know some of the triggers in the workshop (eg. breathing immediately affected when turning on DC with the oversized/leaking plastic bags).......
... this is the opposite of many self reports where people say "I don't see any dust in the air and my body isn't being discomforted at the moment and conclude the air quality in their workshop must be fine" just like people attending a lot of rock concerts/use headphones at too loud a setting and say their hearing is fine (hearing loss has not yet become subjectively apparent)......

..... if you make one change at a time in your workshop dust collection/air filtration and workshop activities, the signals your body is giving off may be sufficient to guide you in improveing the air quality in your workshop

I've had a Dylos particle counter (the cheapest, base model calibrated for 1/5 microns) now for 5 years and have used it to track down problems with dust collection or when I do something new in the shop that might generate excessive dust particles.... otherwise I no longer use it continuously when I'm in the shop because I've come to know, with the dust collection setup I now have and with routine shop work activity, I won't have an air quality problem

good luck

michael

[Peter Aeschliman]

Ian, you raise good points.

On the one hand, I like the idea of the filter acting as a diffuser (won't stir up as much dust), but on the other hand I worry that it won't adequately contribute to the circular air flow I need in the shop. That could be solved by adding some hanging fans in strategic locations I suppose... but then we circle back to the concern about stirring up dust. I tend to think that if I'm doing a good job of collecting dust at the source, and collecting dust that escapes my DC via air filtration, there shouldn't be much dust left over to stir up. So I want to approach the "dust stirring" issue by solving the root cause, which is, don't let the dust settle in the first place- capture it!. So long story short, I've talked myself into wanting that circular air flow in the shop, which means that I'll need to overcome the diffuser effect by via additional fans.

As for the pressure drop, this is definitely a concern. Interestingly, one of the fans I saw while looking around actually comes with a cartridge style filter attachment:

http://www.amazon.com/247Garden-Inline-Carbon-Filter-Outlet/dp/B009BC1570/ref=sr_1_7?ie=UTF8&qid=1366994585&sr=8-7&keywords=8%22+inline+fan

Amazon doesn't provide much detail on the filter, but it's way smaller than my Wynn filters. I'm not sure how it would compare to my Wynn filters in terms of static pressure impact, but if I were a betting man, I would assume my Wynn filters will do a better job due to their size.

The good news is that the expensive part of this is already done- the filters. This fan is pretty inexpensive, so I'm tempted to just take the risk on Bill Pentz's recommendation:

http://www.amazon.com/inch-inline-high-efficiency-blower/dp/B004YXDR22/ref=sr_1_12?ie=UTF8&qid=1366994585&sr=8-12&keywords=8%22+inline+fan

[Peter Aeschliman]

Peter,

I'm not a doctor..... but it sounds from the above that your immune system has been comprised.....

the bad news is, of course, if this is the case, that it could get worse if you don't track down what is attacking it and deal with the 'triggers'; you may have to give up or significantly modify activities you enjoy like woodworking....

the good news is that you can recover some or most of the losses to your immune system, etc.

ironically, another small piece of the good news is that given that your body appears to be 'sensitized' to the triggers that are affecting your breathing, to an extent your body can act as a dust particle counter/monitor ........ you already seem to know some of the triggers in the workshop (eg. breathing immediately affected when turning on DC with the oversized/leaking plastic bags).......
... this is the opposite of many self reports where people say "I don't see any dust in the air and my body isn't being discomforted at the moment and conclude the air quality in their workshop must be fine" just like people attending a lot of rock concerts/use headphones at too loud a setting and say their hearing is fine (hearing loss has not yet become subjectively apparent)......

..... if you make one change at a time in your workshop dust collection/air filtration and workshop activities, the signals your body is giving off may be sufficient to guide you in improveing the air quality in your workshop

I've had a Dylos particle counter (the cheapest, base model calibrated for 1/5 microns) now for 5 years and have used it to track down problems with dust collection or when I do something new in the shop that might generate excessive dust particles.... otherwise I no longer use it continuously when I'm in the shop because I've come to know, with the dust collection setup I now have and with routine shop work activity, I won't have an air quality problem

good luck

michael


Hi Michael- I think you and I were posting at the same time.

I hear you, and I really appreciate your concern. These symptoms are only very recent. I've been working with Black Walnut almost exclusively over the last few years. The first time I cut into the stuff, it bothered my respiratory system. Nothing extreme, just obnoxious. Much worse than the Cherry and Maple I was accustomed to. What I haven't said is that I've also dabbled in metalworking recently. At one point a few weeks ago, after using my angle grinder on some steel, I noticed my lungs were really irritated. There was somewhat of a cloud of grinder dust in the air. I actually had to leave the shop and let my air scrubber work for a few hours. I also have a sandblasting cabinet that is ventilated using my shop vac. I use aluminum oxide media. I wear my respirator while I do that, so it hasn't really bothered me.

Over the last month or two, my lungs have been a bit more sensitive. Again, nothing extreme here. I'm just trying to pay attention to what my body is telling me.

I think I might be communicating my symptoms in this thread in such a way that it's coming across as far more extreme than it is. But frankly, it's the catalyst for my dust collection/air quality projects. So it is significant enough for me to take action.

Of course I hope I haven't permanently screwed up my respiratory system. Whether my symptoms are temporary or permanent, I need to take action. I just hope I haven't taken action late enough that I have to walk away from woodworking altogether (I highly doubt that though).

[Michael W. Clark]

So long story short, I've talked myself into wanting that circular air flow in the shop, which means that I'll need to overcome the diffuser effect by via additional fans.

As for the pressure drop, this is definitely a concern. Interestingly, one of the fans I saw while looking around actually comes with a cartridge style filter attachment:

http://www.amazon.com/247Garden-Inline-Carbon-Filter-Outlet/dp/B009BC1570/ref=sr_1_7?ie=UTF8&qid=1366994585&sr=8-7&keywords=8%22+inline+fan




Hi Peter,
I know you are concerned about direction of flow through the cartridge filter, but I think if you clean your filter adequatly, you could reverse the flow without any issues. This being said, you could put the cartridge filter on the inlet of an axial fan as shown in the BP link, then discarge through a straight piece of duct. This would give you the most filter area in the smallest space and still promote your air currents. I just looked at the picture in the BP link and didn't read the text, this may be what he is suggesting.

The carbon filter in your filter fan link, will not be good for your intended purpose. The carbon filter is for odor control and will plug with significant particulate levels, thus limiting airflow and your circulation effect.

If you are going to build the air scrubber box arrangement, look for envelope style filters with the media/filtration requirements you want. The envelope style will give you more filter area. You can include a framework inside your box to increase the number of filters if you desire, but there are a lot of sizes commercially available. You may have to go to a commercial/industrial filter manufacturer for more choices. The prices should be competitive. A regular furnace filter will work for the intake or a register grill. The furnace filters will reduce the loading on the more expensive envelope filters, but it may be minimal depending on your dust size. The register grill would at least act as a safety guard over the fan intake.

Mike

[Peter Aeschliman]

Hi Peter,
I know you are concerned about direction of flow through the cartridge filter, but I think if you clean your filter adequatly, you could reverse the flow without any issues. This being said, you could put the cartridge filter on the inlet of an axial fan as shown in the BP link, then discarge through a straight piece of duct. This would give you the most filter area in the smallest space and still promote your air currents. I just looked at the picture in the BP link and didn't read the text, this may be what he is suggesting.

The carbon filter in your filter fan link, will not be good for your intended purpose. The carbon filter is for odor control and will plug with significant particulate levels, thus limiting airflow and your circulation effect.

If you are going to build the air scrubber box arrangement, look for envelope style filters with the media/filtration requirements you want. The envelope style will give you more filter area. You can include a framework inside your box to increase the number of filters if you desire, but there are a lot of sizes commercially available. You may have to go to a commercial/industrial filter manufacturer for more choices. The prices should be competitive. A regular furnace filter will work for the intake or a register grill. The furnace filters will reduce the loading on the more expensive envelope filters, but it may be minimal depending on your dust size. The register grill would at least act as a safety guard over the fan intake.

Mike

Thanks Michael- I'll call Wynn and ask about the flow direction. I definitely would prefer to pull air through the filter (outside in) for air circulation reasons. After cleaning the filters (compressed air, then water), I could always run them for a few hours outside to get anything left over.

As for the carbon filter in the link- yeah, I definitely wasn't thinking about using that for my application. I just thought it was a clue that a these fans can work with filters without burning out or having the airflow hurt too badly. But I won't know until I try it with my Wynn filters.

I'm pretty much decided at this point that I'm going to go the BP route since I already have the filters on hand. It will save me money and time, and hopefully yield the same results. Plus, I can also buy the upgraded filters for my jet unit and have three air scrubbers in the shop. Can't hurt!

[Peter Aeschliman]

I just spent about 2 hours cleaning out my Wynn filters. I'm shocked by how much dust was in them. I've cleaned them a few times over the last 3 years with compressed air... But wow. I went pleat by pleat washing them with water. It took a long time to get the water running somewhat clear.

Needless to say, I won't be reversing the air flow direction after all. I'll need to blow through the filters (inside out)... otherwise I'll be stirring up more dust than I'm catching!

I must have installed my thien baffles incorrectly because it really is amazing how much dust got through. I should probably blame my drum sander.

[Phil Thien]

I must have installed my thien baffles incorrectly because it really is amazing how much dust got through. I should probably blame my drum sander.

Drum sanders are a challenge, even for conventional cyclones.

[David Kumm]

Drum sanders are a challenge, even for conventional cyclones.

Most cyclones are not designed for fine dust. Bags are generally used rather than cartridges due to the inevitable loading. Dave

[Michael W. Clark]

I went pleat by pleat washing them with water. It took a long time to get the water running somewhat clear.

Needless to say, I won't be reversing the air flow direction after all. I'll need to blow through the filters (inside out)... otherwise I'll be stirring up more dust than I'm catchin.

So if you spent all that time cleaning them, why do you think there is a problem in pulling air outside to inside? I seriously doubt you would dislodge more dust with the fan than you did washing.

Most industrial cartridge filters go outside to inside.

Mike

[Peter Aeschliman]

They still looks pretty dirty, even after all of the cleaning... I think they'll still spew tons of dust. I'd rather not take the chance.

[Peter Aeschliman]

All,

Just thought I'd follow up on what I ended up doing. Since my last post, I installed the ebay Cyclone with my 3HP impeller and set it up to exhaust outside, got a new shop vac and rigged up a Dust Deputy in front of it, set up the pentz-style air filtration units on my Wynn filters, and picked up a Dylos (the .5 micron unit).

Re: the Wynn filters, I mentioned before that I spent a lot of time cleaning them out with compressed air and water, in the hope that I could change the configuration so that I could suck through the filters instead of blow into them. After the cleaning I was concerned that they were still so dirty that it was going to spew dust if I changed the flow direction.

The dylos demystified that. I ran the filters in that configuration as a test, and the dylos definitively showed that it wasn't a problem. The setup couldn't be simpler. I bought two 750 CFM 8" inline fans. They seal perfectly to the round gasket on the wynn filters. I mounted them vertically in the middle of the two long walls in my shop, with 8" elbows on the exhaust to aim the air flow. They work really darn well- there's a very clear circular air flow in the shop now. The downside is that they're really loud- the motor isn't loud, but the sound of rushing air is. It's not so loud that I need hearing protection, but it produces a noticeable amount of white noise.

What I love about this setup is that the filters are mounted at face level and below. Many people express concerns that ceiling-mounted air filtration units pull dust up past your face. That isn't a concern with this setup. One of the two filters is mounted on the other side of my assembly table where I do most of my sanding. The downside is that some of the filter is close to the wall, which under-utilizes the filter media. I'm okay with that trade off though.

I wired the fans together on a timer switch, which works great.

Here are some pictures of the filter units. Please excuse the messy shop- I had to take down my clamp rack system to do this (I now have to completely redo that) and I didn't bother to clean up before taking any pictures.

http://i66.photobucket.com/albums/h255/peteraeschliman/IMAG0003.jpg (http://s66.photobucket.com/user/peteraeschliman/media/IMAG0003.jpg.html)

http://i66.photobucket.com/albums/h255/peteraeschliman/IMAG0004.jpg (http://s66.photobucket.com/user/peteraeschliman/media/IMAG0004.jpg.html)

Here's the lowest dylos reading I've seen so far. This is after running the filters for probably 30 minutes without creating any new dust. The number on the left is the .5 Micron reading. 75 and below is in the "excellent" range. It shoots way into the thousands when I use my table saw, despite above and below-table dust collection. But after about 10 minutes it comes back down to the 300 range.

http://i66.photobucket.com/albums/h255/peteraeschliman/IMAG0010.jpg (http://s66.photobucket.com/user/peteraeschliman/media/IMAG0010.jpg.html)

As for the new cyclone setup, on the one hand, I'm thrilled about venting the fines outside. No more worrying about filters. On the other hand, I've experienced a noticeable drop in suction. It still sucks really well, but my 4-bagger/thien baffle/wynn filter setup sucked noticeably harder (it spewed dust though- I never got a good seal to the bags). The cyclone is of decent enough quality for the price, although the circular part of the cyclone was very out of round (as you can just barely see in the below pic, I had to shim it to get it to sit snuggly in the ring I built). The gauge of the steel is relatively thin, so the top flat part of the cyclone pops in and out under suction. Not a major problem, but I do think it could benefit from some thicker steel. You get what you pay for though. For the price, I'm very pleased.

I can tell you that a Clear Vue cyclone is in my future though. I'll give this setup a few years, but I do have that nagging "you get what you pay for" voice in my head.

http://i66.photobucket.com/albums/h255/peteraeschliman/IMAG0005.jpg (http://s66.photobucket.com/user/peteraeschliman/media/IMAG0005.jpg.html)

All said and done, the air quality in my shop is massively better now. I've decided that I need to wear a respirator while making dust, and let the dylos readings come down into the "good" air quality range before I take my mask off. I hate wearing my respirator, but I would hate losing lung capacity even more!

Thanks everyone for your input on this project.

[michael osadchuk]

Peter

Thanks for posting your air cleaner(s) solution; it's quite interesting and, given the Dylos particle readings, pretty effective.

It's interesting to underline that maintain some kind of air circulation in the shop helps air cleaners to do their job.... on the basis of air particles will settle faster in dead air and be "unavailable" to be collected.

One outcome seems puzzling.... I would have thought that with venting the "fines" collecting by cyclone outside would have boosted "the suction" rather than diminished it a bit, on the basis of removing the back pressure a cyclone filter adds to the system.

thanks again

Michael

[Peter Aeschliman]

Micheal, I was surprised by the suction loss as well.

Before, I had thein baffles and the Wynn cartridge filters that I re-purposed for the air filtration units. I know that cyclones hurt suction, and that would explain why bill pentz recommends a 5hp motor with a 16" impeller... mine is only 12".

But the before and after aren't that different- before, I had filters and the thien baffle. After, I have no filters and a cyclone.

The body of the cyclone is 18"... from what I've read on Pent'z website, with my smaller motor and impeller, I should actually be using a 20" body, which would mean the cyclone would be too tall to fit under my 8' ceilings once scaled up.

Anyway, in a few years I'm sure I'll trade up to a clear vue cyclone. Lucky for me, they're only a 30 minute drive from my shop... so I can save a lot on shipping costs.

[Jim Neeley]

Peter,

Just in case you don't already have this covered...

You mention your DC is working harder now that it's venting outside. This is good because it gets the dust out where it belongs. :-)

What are you doing to allow make-up air to re-enter your shop? Any pressure drop between outside and the inside of your shop must be created by your DC. This makes the DC work harder and starves your system for air, especially if you have a marginal / undersized impeller/motor setup. A rule of thumb for return air ducting sizing is that it should be 10X the area of the high-pressure duct to ensure you get the full benefit of outside exhaust. For a 6" exhaust this is a bit over 2 square feet. Have you tried opening a window or door to the outside to see if this makes a difference?

Jim

[Peter Aeschliman]

Great point, Jim. The weather has been pretty nice in the Seattle area lately, so I've been working with the garage door open. I will definitely need to figure something out for the winter though- I had no idea the return air ducting needed to be 10x the area of my 6" duct. Sheesh, I'm not sure where I'm going to be able to make a hole that large. I was thinking that I'd come up with some kind of flap vent to save some heat for the times when I'm not running the DC, but it's going to take a lot of them to make 2 sqft!

[Jim Neeley]

I'm planning around a similar issue for my Clearvue cyclone. I'm not exhausing outside but plan to close-in my DC for noise purposes. I'm looking at a rectangular gable vent (search the BORG for pictures) as something that will provide the area while leaving a finished appearance to the room.

Just my $0.02..

jim