Wood Dust & Welding Fume Extractor

[diarmaid]

Hi all.

1) Can anyone suggest a workshop extractor that when set up with ducting will take wood chips and dust particles from a cnc router and woodworking machines, but will also take welding fumes and fumes/dust from a cnc plasma table.

1a)These seem to be suitable for fumes etc but say nothing about wood dust and chips.
http://www.acs-ltd.com/acsmf12-15.htm

1b)There are a huge amount of wood extractors so Im not going to post a link to one example, but suffice to say they say nothing about welding and metal working fumes.

2)Can one unit be got to do both jobs....even by changing the filter although this would be unwanted hassle? Or do you just have to buy two and turn on whichever one you need at the time.

Thanks.

[ger21]

I'd say that you need 2 different units.

[2muchstuff]

There is a major difference between the two. The first one that you linked to is strictly used for fumes and airborne dust particles. They consist of several filter elements progressing from coarse to finer and finer. Some have an activated charcoal/carbon as the last one for odor removal. They are usually hung from the ceiling, have a small fan and recirculate the room air.

A wood/chip extractor has a much larger fan that will be able to pick up larger pieces. From there they go into a cyclone and or some kind of collection container. The air then is usually discharged outside or can be run thru a filter and returned back into the room. A cyclone can extract a fair amount of dust out of the airstream.

A wood/chip extractor can be used as a fume extractor if it is vented to the outside. The one disadvantage to the wood/chip extractor is the noise level. This is due to the larger more powerful fan, if it can be put in another roon or outside then all you will hear is air moving.

If I had my choice I would use a wood/chip extractor to do both jobs. There is a thread here where someone built a cyclone and I believe he used it with mdf and had good results.

[diarmaid]

Thanks. That makes it a bit clearer. I have already sourced a variety of extraction equipment to deal with the wood dust problem, and really didn't want to have to also invest in more equipment for the metal working side. The kit will be venting outside so should do fine. I saw the info about the mdf cyclone and visited bill pentz site.

[Mcgyver]

I was puzzling about this today as well, for welding and silver soldering, I think I'll have to make a hood with a blower to outside. There's some good threads and links herein on wood particle filtration, strikes me that if you want safety, you need to either where the correct mask (properly fitted as they always suffix it) OR spend some very serious dollars (ie felder is that i've seen that meets the specs) All they other bag, filtration, cyclone etc home shop stuff is not of much use - it just doesn't have the ability to either/or handle the air volumes in real time or filter out the fine particles. because its expensive to properly address these issues, many people seem to be able convince themselves that they diy units are ok, but you do only get one set of lungs - worth doing some objective investigation imo

another type of dust extraction we need to be aware of, for grinding, For me its primarily off the t&c grinder and surface grinder. esp if you are grinding carbide, it its a real concern.

[diarmaid]

I've been doing quite a bit of research on this. Have you visited bill pentz site McGyver at http://billpentz.com/woodworking/cyclone/Index.cfm

There are quite a few industrial extractors available for under $1000 with rates approximating about 2000m3 per hour and .5micron filtration which I think is fairly good if its venting all particles below .5microns outside. But 1k is probably too much for a lot of DIY'ers so they go for the $200 range. Yet they wouldn't think twice about 1k for a good piece of equipment.

Something else Im looking for info on....I was going to get a Triton powered respirator for woodworking http://www.onlinetoolreviews.com/rev...respirator.htm

This however doesn't provide any protection from welding fumes. The respirators I've seen that can be fitted with welding filters, or wood dust filters, are not fitted with dark tinted glass for use while welding....whats the story with this. Is there an extractor for welding fumes that can actually be used 'while' welding?

[Mcgyver]

diarmaid, that was the site i was thinking of - Bill's done a great service in putting that together. He was the one that endorsed the Felder. from his recommendations section.

I recommend you build or buy my cyclone and blower design and then use the recommended 5 hp Leeson motor and 15” impeller to move a real working 1000 CFM needed for the best fine dust collection. If you are unable or unwilling to do the cyclone and blower construction yourself, then I recommend you buy a system kit from Clear Vue Cyclones. The only other viable option I know of for good indoor dust collection is to buy a Felder Dust collector.

I've been familiar with Felder for a while and doesn't surprise me that they make the best - I thought it was a lot more the 1G though (not to belittle 1G mind you). these are expensive hobbies to begin with, but it beats the heck out of lung disease.

don't know much about welding fumes, except that one of the bad parts is the ozone (O3) that welding produces - not good stuff and the worst offender is plasma! Its criminal that companies sell ozone producing machines under the guise that it good for you, although the quanities may be negligible! Anyway, the point is that you'd be trying to filter out molecules vs (albeit very small) pieces of wood by using the same system. That plus the fact that welding fume extraction isn't picking up particles, just venting volumes of air, makes me think a hood & large blower vented out side is the way to go.

[diarmaid]

I was looking at getting a Unit DustFilter Solution from this company, but thanks for the Felder link. Im going to have to run up some comparisons for the two.

http://www.airplants.co.uk/unit.html

Felder Link: http://mk.felder-gruppe.at/?page=shop_node&node=154

[Geof]

Originally Posted by Mcgyver welding fume extraction isn't picking up particles, just venting volumes of air, makes me think a hood & large blower vented out side is the way to go.

To conserve on heat in cold weather you can use activated carbon filters. Commercially available welding fume extractors which have a smallish hood on the end of a flexible nozzle discharge back into the workspace and they just use filters to trap the bad stuff.

[Mcgyver]

Geof, they still don't remove the ozone, do they? that was why i thought even a really good filtration system wouldn't be as good as exhaust, but i hear you on the air exchange/heat loss issue for us northerners! as a hobbyist i have the luxury of waiting for warmer weather for the welding projects, obviously not an option for a business

[diarmaid]

Hi all. Have a look at this welding fumes video analysis I found. Its quite good.

http://www.cdc.gov/eLCOSH/abstracts/...0/a000076.html

[Geof]

Originally Posted by Mcgyver Geof, they still don't remove the ozone, do they? that was why i thought even a really good filtration system wouldn't be as good as exhaust, but i hear you on the air exchange/heat loss issue for us northerners! as a hobbyist i have the luxury of waiting for warmer weather for the welding projects, obviously not an option for a business

Yes activated carbon does remove ozone. I stole this from a link I found via Google:

1: Am Ind Hyg Assoc J. 1999 Sep-Oct;60(5):589-600. Related Articles, Links


Evaluation of activated carbon filters for removal of ozone at the PPB level.

Lee P, Davidson J.

University of Minnesota, Department of Mechanical Engineering, Minneapolis 55455, USA.

Performance of filters for the removal of ozone at ambient concentration is characterized. The removal efficiency and pressure drop of 10 commercial filters--including 8 made of granule or powdered activated carbon, 1 activated carbon fiber filter, and 1 packed bed made of an ozone catalyst--were measured for an influent ozone concentration of 120 ppb at 50% relative humidity and 2.54 m/sec face velocity. Activated carbon filters can be very effective at ozone removal, although not indefinitely because chemical reactions of ozone and carbon change the carbon. Initial efficiencies of the 1.27-cm thick flat samples varied from 4.6 to 98.3%. Analysis of the structure and composition of the filters with scanning electron microscopy and X-ray photoemission spectrometry showed chemical reactions permanently changed the composition of the carbon and decreased the surface area. Consequently, removal efficiency decreased with use. Moreover, it was not feasible to regenerate the filters by simply removing them from ozone-laden air. Changes in relative humidity, from 20 to 80%, had no measurable effect on the performance of a granule activated carbon filter. However, because the rate of adsorption of water is faster and the pores are smaller in activated carbon fiber, efficiency of the fiber filter decreased when relative humidity was raised from 20 to 50%. A quality factor, equal to the ratio of a threshold breakthrough time and pressure drop, is used to compare filters. In general, those with higher carbon surface area per unit volume had higher efficiencies and greater pressure drops. Future work should address the removal of ozone in the presence of other gases.

PMID: 10529990 [PubMed - indexed for MEDLINE]