Protection from dust

[Dale Critchlow]

I have been showing symtoms of allergy to wood dust, to I talked with a Professor of Environmental Engineering at the local university today about wood dust control. He does research on pollutants and has a room full of rats which he uses for testing, so he is an hands-on engineer.

Repirators: He says that the full-face respirator made from a soft material is the best. The half-face is next in effectiveness.

The battery powered respirators are not as effective. The main advantage is comfort. He does not allow his graduate students to use these units.

The fit of the respirator is critical. He has each student tested by an expert with the respirator in place to make sure it has a good fit.

Cyclones: He says that the common cyclone configuration with the filter after the blower typically allows significant leakage of very small dust (a few microns and less in diameter). Therefore, using a filter rated at 0.2 microns is not effective unless you can somehow seal the leaks between the blower and the filter. Apparently, this is very difficult to accomplish for very small particles. According to him, the only sure way is to use high quality welded joints.

So I have to rethink dust control in my shop. One thing I have already done is replace the 0.2 micron filter stack with a 6" HVAC flex-hose going directly to the outside for warm weather use.

Are there some experts out there with comments and suggestions?

Dale

[Frank Pellow]

The best expert that I found is Bill Pentz and he is a member of the Saw Mill Creek forum.

You should check his extensive web site at:

http://cnets.net/~eclectic/woodwork...clone/index.cfm

[Dale Critchlow]

Frank: Thanks for the suggestion.

Yes, I am very familiar with Bill Pentz's website. I built my cyclone following his design a couple of years ago. In fact, he has my description of the construction on his site.

Bill's website is quite extensive and covers many of the questions. However, I think there is a lot more to the dust control problem than even he has on his website.

I know several people who have given up woodworking because of allergies. These include two engineering students in my classes who are in their late 30's. They had to change career paths.

I am hoping that if I can learn enough about how to control the dust, I may be able to continue with woodworking for the long term. For example, I now understand that I must make some major modifications the ductwork leading from the blower on my cyclone to the filters. However, I am not sure of the best way to do it. If the Environmental Engineer I referred to in my first post is correct, I will have to do something special to stop the leaks.

Suggestions would be appreciated.

Dale

[Jim Becker]

Dale, in addition to taking all the obvious precautions, including those you spoke of in your initial post, consider that you really need to eliminate specific species from your woodworking as part of your sensitivity mitigation. Keeping those species, whatever they may be, out of the loop will help you stay more comfortable. For example, many folks are very sensitive to black walnut and continued exposure actually increases their sensitivity. My locksmith had to stop woodworking years ago because of this...and he was a carver.

So if you have any idea about specific woods that affect you a lot, stop using them in addition to wearing personal protection and insuring you are collecting as much dust at the source as you can.

[Dale Critchlow]

Jim: Thanks for the note. I don't do much work with the more toxic woods. I work mostly with cherry and maple. I have noticed some sensitivity to mahoney and walnut in the past.

I have come to understand that there is a lot more to the wood dust problem than is commonly understood. In fact, there seem to be a lot of myths out there.

There must be professionals (in health, engineering, etc) working with wood who really understand the issues in depth. I would like to hear what they have to say.

Dale

[Jim Becker]

Dale, I was thinking about this thread as I was on the train into NYC this morning; specifically about the comments that your professor friend made about the dust leakage between the blower and the filters. I guess I have a little issue with that, at least theoretically. In my case, the connection between the blower on my Oneida cyclone and the external filter has a heavy rubber gasket. There is no perceivable leakage and I have those bolts cranked down tight. I think there is far greater danger from the fine particles that get into the air directly from the milling or sanding operation than from leakage post-blower if one takes care in assembling their system...and that includes both commercial offerings and shop-built systems like yours. I'm not saying it's a perfect situation, but Terry and Bill and Don Beale and others who council about hood design and CFM have the right idea, IMHO. The more you stop at the source, the better off you will be. Leaks at the other end can be dealt with through effort, sealant, tape, etc.

[Jamie Buxton]

Cyclones: He says that the common cyclone configuration with the filter after the blower typically allows significant leakage of very small dust (a few microns and less in diameter). Therefore, using a filter rated at 0.2 microns is not effective unless you can somehow seal the leaks between the blower and the filter. Apparently, this is very difficult to accomplish for very small particles. According to him, the only sure way is to use high quality welded joints.


Dale

A lot of what you reported makes good sense to me, but the requirement for welded joints strikes me as strange. It is not difficult to make water-tight joints without welding. A seal that can hold water will hold dust particles, even small ones.

[Bob Hovde]

Have you checked the information at http://www.zianet.com/calexander/index.html in regards to capturing the dust at the source?

Bob

[Dale Critchlow]

Bob: Thanks for the link to Alexander's website. It is interesting. I guess you have to buy the tapes to get the full story.

I did notice some negative comments about the effectiveness of filters to remove small particles. In fact, he mentions venting outside instead.

Dale

[Dale Critchlow]

Jim: In reference to you note about your Oneida cyclone. I will have to talk to the professor more about this. Perhaps, he is not familiar with the Oneida system. I suspect that the duct work on the Oneida system is welded.

I see now that one problem with my homebuilt cyclone is that I simply used the 6" hose and clamps that came with the original Delta DC to connect to the filter. It looks like I should rebuild these. Perhaps, I can buy some fittings.

The 0.2 micron Torit filters I used do have a thick gasket on one end. I suspect if they will not leak if really clamped tightly.

By the way, which train do you take into NYC? I lived in Westchester County for 23 years, but luckily I didn't have to commute. This was before they electrified the Harlem Division.

Thanks,


Dale

[Terry Hatfield]

Dale,

I don't know about this one. I feel ceratin that I have a very good seal post blower on mine. I agree that the ideal situation is to exhaust outside. One thing very seldom mentioned about exhausting outside is that you have to make sure some of the exhausted dust is not coming back in open windows and doors.

Atleast 6 months of the year here have to have heated or cooled air to be able to work in the shop comfortably so exhausting outside is not really an option for me. Honestly, I feel perfectly safe filtering my air and I don't see making an air tight seal between the filter and the blower is a problem. I Would think that some combination of mastic backed foil tape and caulking could be used to seal just about any configuration of outlet pipe/hose/filter.

Are you getting leakage on yours? With particles sup-micron sized would you be able to see a buildup at the leak? I really don't know for sure. I know I did have a leak at the filter connection when I first built mine. It didn't take very long to be able to see the dust buildup on the outside of the pipe. I caulked it and have not seen any more leaks.

Terry

[Jim Becker]

By the way, which train do you take into NYC?
Amtrak out of Trenton NJ.

[Allan Johanson]

Hi Dale,

Maybe this is a crazy idea, but hopefully someone here can quickly shoot it down or confirm it might work:

Acoustical sealant

Maybe you can apply an extremely liberal amount of acoustical sealant on the pipe - between the pipe and the flex hose - and use that as a way to stop the fine dust from leaking between the flex hose and the pipe. Acoustical sealant is used in vapour barriers in homes to stop air leaks. It never truly hardens, which seems to me anyhow, a desireable feature to help stop leaks.

Thoughts anyone?

Allan

[Mike Cutler]

Dale. I do not claim to be an expert on cyclone construction, but I have to agree with the rest. It should not be difficult to achieve an airtight seal between the blower and the cyclone. Perhaps the unit that he is used to is quite abit larger and more powerful than the typical "home Shop" cyclone.
However, I do claim to be quite knowledgable on repirators. I've spent 25 years in the Nuclear Power industry wearing all types of respirators to protect from airborne radioactive "particles" being inhaled, or ingested.
At one end of the scale you have a common 3M dust mask, this mask has a NIOSH rating of 50 ( This means that for every 50 particles of airborne contaminants, 1 particle will get through the mask) At the other end of the scale you would have an SCBA( Self Contained Breathing Apparatus) this is the rig that you see fire fighters wearing, it has a NIOSH rating of 15,000. The respirator that your friend is speaking of is a negative pressure full face respirator, it has a NIOSH rating of 1000. An airfed positive pressure full face repirator has a NIOSH rating of 5000. The half mask repirator has a NIOSH rating of 500/1000. These number represent the use of a respirator in a moving working enviorment, obviously if you were sitting in place the SCBA would be substantially higher in rating but in it's actual use, fire fighters/ rescue teams running up and down stairs and in and out of buildings the rating comes down due the exertion and activity level.
I have a respirator fit test yearly, and have to undergo a Pulmonary Function Test in addition to meeting all OSHA training requirements on a yearly basis to maintain the respirtator qualification. The proper fit of a repirator is paramount to it's proper operation.
The ideal setup would be to have the cyclone exhaust outside, but only our friend from California could get away with this long term.
There is no 100% solution, so we have to do the best we can. I currently have a Jet DC 1100 but it will soon be replced with a cyclone.

[Jim Becker]

Alan's post brings another thought to mind...the flex hose in the blower to filter path. I'd eliminate it. Hard-piping it with appropriate materials should provide a much better opportunity to seal this portion of the system. The flex to pipe/hood/adapter junction will always be hard to seal no matter how much you crank down the compression bands. Nature of the beast.

[Jim Taylor]

Although I have some minor medical training, I am not a doctor... so take this for what it is worth.

I have a significant allergy to shell fish, and have had a small number of accidental contacts, which have sent my body into long bouts with Asthma type conditions. After the first incident occured, I spent almost two years getting back to "normal". During that time, I seemed to be allergic to almost everything. Initially, I accepted that I needed to use a common Asthma medication. But over time, I came to believe that my body was becoming addicted to the medication, and that I might never return to my "normal" state. As a result, I spent a substantial amount of time reading up on allergies, and paying attention to how my body reacted to various substances. along with lots of doctors.

I have concluded that my allergies are not really based upon any one simple substance (with the exception of shell fish), and that I can control my bodies reactions through broader attention to my personal behavour. By and large, the type of reactions I have, seem to be connected to my bodies over-reactive immune system. I also have come to conclude that the immune system is never really on or off, but rather at any of a series of alert levels. The more components which are in the system, the higher the alert level, and the greater the risk of reaction. Immune system activity causes inflamation in tissue. If this inflamation is not dealt with, it will gradually escalate into a larger problem for me. For me the following are important factors in avoiding allergies:

- avoidance of big problem substance (shell fish)
- regular aerobic style exercise
- reduction of allergy increasing dietary items (diary, red meat...)
- increase of immune system improvers ( vitamins, fish oil, anti-oxidants)

I don't need to keep on track of all these items, all the time (expect the shell fish). However, as I start to recognize the symptoms, taking the steps above has always brought be back into a lower alert level (as I see it).

My current alert level indicators are:

1. can't pet the cat
2. can't be in the same room as the cat
3. can't pet the dog
4. It is time to get things back in line

After a lot of trial and error my "normal" regiment is:

1. no red meat
2. minimze dairy, especially milk
3. no special exercise other than occassional walks and work
4. 1 cup of green tea a day

If this does not work, my only recourse is back to the treadmill or elliptical workout for 45 mins a day.... or back to the medication (which I may do occassionally 1-2 times a year for a day or two... just being lazy).

I'm posting this, not to suggest that you needn't maximize your dust collection. Rather to suggest that there are additional things which could improve your overall allergy status.

-Jim

[Dale Critchlow]

Mike: Thanks for the info on NIOSH ratings. This gives me some numbers to work with as I search the web for respirators.

Do you have any recommendations?



Jim (and others): My present thinking is that I will get rid of the flex hose between the blower and the filter. Now I have to figure out how to build it.

Dale

[Jim Becker]

Jim (and others): My present thinking is that I will get rid of the flex hose between the blower and the filter. Now I have to figure out how to build it.
Dale, one thing to consider is that there is "rule" that says your filter(s) need to be next to the cyclone/blower. That aspect should make it easier for you to deal with making the connection between the filters and the blower more robust. Although many folks are very pro-PVC for duct work, this is one place that it might be easier to use metal as you can leverage adjustable elbows to get the exact angles you need, etc. Of course, you'll need to use a judicious amount of foil tape and HVAC mastic to seal things up at that point. Do use long-radius elbows, too. You can also increase the size of the duct between the blower and the filter(s) with no problem. That further reduces any remaining back-pressure, if any exists.

[Scott Coffelt]

I have and control my asthma through proper medication. I have found the best is ADVAIR, since I have taken this medication, I have had 0 (ZERO) incidents (for about 10 months). I have tried to seal my system, use the DE Cyclone, .02 micron Torit filters, all sanding is now done with the Mini-Fein attached. I don't but should use a better mask.

Try to take extra care when working with more intense woods (i.e., Wlanut, Exotics, etc.). I am not sure I like the idea of venting outside, seems kind of like factors dumping waste into streams. :rolleyes:

But I guess if the system is wokring right very little escapes and the crude in the air is worse anyways, right?