Thread: Fine dust Problem??

Originally Posted by Groggy

My statement was:

"If your neighbours are close by and if the dust is over 0.4 micron then pumping it outside unfiltered is exposing people to the same risks we try to avoid for ourselves."

There is very little difference in the fine wood dust exposure to the community between someone that
a. vents an unfiltered DC outside
b. does nothing at all to collect any dust - very fine dust will eventually leak out of shed into the neighborhood
c. that uses an unfiltered DC inside their shed - very fine dust will eventually leak out of shed into the neighborhood

The net result of all 3 cases is that the area around the outside of the shed and into the neighborhood will contain fine wood fibres. The exposure risk is low because;

1) The fine fibres are diluted by the atmosphere - peeing in the ocean effect
2) Depending on the breezes, after an hour or so the levels will drop probably below detection limits.

However, there is a big difference to woodies operating inside a shed between (a) and (b)/(c). In case (a) the dust is removed from the shed reducing their exposure, whereas (b)/(c) means the woody is constantly bathed in a soup of fine particles.

To the neighborhood case (a) represents higher exposure for shorter period of time. In cases b/c lower exposure over a longer period of time.

If the DC is filtered, overall neighborhood exposure is reduced PROVIDED the DC is not run for longer.
Same with 0.1 micron particles. Generally considered OK PROVIDED there are not too many generated.

Originally Posted by Diesel Fitter

So if I've got the gist of this... my bottom shelf, line single dusty only collects the larger particles? and the rest recirculate if the filter is in the shop with me?

yep - same with shop vacs - shop may look clean but you are bathed in a soup of fine dust you cannot see.

Which means that regardless of cheap dust extraction (or none), my family and neighbors are being harmed as the fine stuff gets outside eventually?

No -
- the atmosphere dilutes the particles so their (and your) exposure is reduced
- weekend warrior shouldn't make enough constant dust to constitute a danger

so I should mount the outlet in the window (after the filter) and not worry too much as I'm only a weekend wood-worrier. Is that the basics?

yep - that's what I recommend to all people who ask me about it

Sorry if I offend anyone.

The main reason I start this post is that I KNOW the very fine sub-micron dust will pass thru the shopvac HEPA filter and float around.

SO,
The main idea is to WET the fine dust so that they don't float around.

Problem with Bill's solution is I cannot connect a 6" (150mm) host to say my handheld router and expect to be able to use it.
So he has no real solution to that dust collection problem.

When my hands are full of dust, I can follow Bill. put my hand under a 6" cyclone inlet
OR
just simply wash my hands or wipe it with a damp cloth.

How best to wet the fine dust just need POSITIVE IDEAS.

Perhaps a very fine misting unit in your shed?

Originally Posted by BobL

yep - same with shop vacs - shop may look clean but you are bathed in a soup of fine dust you cannot see.


No -
- the atmosphere dilutes the particles so their (and your) exposure is reduced
- weekend warrior shouldn't make enough constant dust to constitute a danger



yep - that's what I recommend to all people who ask me about it

Awesome, you guys and this forum have really filled in some blanks for me, I am now safer and more equipped to tackle the projects SWMBO has for me, Thanks heaps!!!!!
Cheers and still learning, DF

Originally Posted by reuelt

Sorry if I offend anyone.

The main reason I start this post is that I KNOW the very fine sub-micron dust will pass thru the shopvac HEPA filter and float around.

SO,
The main idea is to WET the fine dust so that they don't float around.

Problem with Bill's solution is I cannot connect a 6" (150mm) host to say my handheld router and expect to be able to use it.
So he has no real solution to that dust collection problem.

When my hands are full of dust, I can follow Bill. put my hand under a 6" cyclone inlet
OR
just simply wash my hands or wipe it with a damp cloth.

How best to wet the fine dust just need POSITIVE IDEAS.

Why have you settled on wetting to solve the 'problem', if I may ask? Is it based on some kind of industry process, or just something you worked out based on seeing, say, water trucks spraying water to keep dust down?

Personally (and speaking with my scientist hat on) I think the problem will be getting the water in contact with the dust. What I mean is if you bubble it through water, there will in fact be very little of the surface area in contact with the water(this was mentioned above I think) You may think that making a mist or fog of water might do it, but again there is a lot of space between the water droplets so fewer particles of dust will be trapped than you expect. Also many woods are hydrophobic. You have the overheads of generating mist, consuming water. Still, if you know of any industry process (which might not even scale down) I'd like to know.
I think before you even go to extreme measures to trap dust from your DC, you need to look at reducing uncaptured dust at the tool which is going to add to the ambient dust, more than the exhaust of your DC.

Have you thought about electrostatic capture if you're really that worried.

Cheers
Michael

Originally Posted by mic-d

Why have you settled on wetting to solve the 'problem', if I may ask? Is it based on some kind of industry process, or just something you worked out based on seeing, say, water trucks spraying water to keep dust down?



Cheers
Michael

I got the idea from Worksafe Victoria.

http://www.worksafe.vic.gov.au/wps/w...ds+and+control

Under Paragraph
"Improving housekeeping to minimise dust
Simple changes to work practices can minimise the level of wood dust in the workplace; e.g.
prevent accumulation of dust and wood chips by cleaning/emptying dust collection equipment regularly
use dustless methods for cleaning up such as wet clean up, damping down before sweeping, or using an industrial vacuum cleaner fitted with a HEPA filter. Do not use compressed air to clear work benches or to blow dust off wood products.
implement a 'clean up as you go' policy."

Key words
WET Clean up & DAMPING down before sweeping.


The Victorian Work Safe Authority calls adding water "dustless methods".
Doesn't that mean that water will stop the fine dust from being air borne?

I sucked wood dust through a self-built mini-cyclone into a SHOPVAC. The drywall filter bag & HEPA filter appears VERY CLEAN. Obviously the mini-cyclone is working well.
But what I cannot see - that small quantity & very fine harmful dust is what I am considering passing through water. Not all the dust.

Best regards

So that seems to be guidelines for dust that has already fallen. And probably wet clean up dust off shelves would be appropriate, or one of those electrostatic cloths. I don't think I would be hosing my workshop floor before sweeping up, the humidity wouldn't be good for tools and machines. Dust that has settled is not the dangerous stuff (unless you fluff it up), you need to focus on trapping the dust at the machine and making a decision about the exhaust from the dusty ie live with it or vent it.

Cheers
Michael

If after collecting all the dust possible you ran the dusty outlet air through a fine water mist all the superfines you cannot see will be washed out of the air.

My dusty used to exhaust into a leanto which housed 2 of 200litre dust collection drums. The outlet of the primary drum fed into the 2nd identical drum then to the fan which had its normal bag attached. The only time there was superfine dust in the filter bag is when the primary drum was full. The entire front of the leanto had a canvas tarp hanging over it to further baffle dust flow. There was little if any superfine dust even after a couple of years.
I did have in mind the water mist idea but it proved to be totally unnecessary.

There are pics of my dusty setup in these forums somewhere.

At the moment I'm doing very little woodwork till I get my new shed built.
It will have a very similar dusty setup, except I'll use twin fans to get more grunt.

When I first started work we used to use wet sawdust when sweeping the hangars to minimise the dust, it worked well. The sawdust sprinkled around helped you keep track of what had been swept and the moisture kept the dust down. One day when the boss was away we tried it without the water and very quickly went back to wetting the sawdust.

Other than that, I have only ever seen water used once to keep dust at bay and that was at Lockheed where they had a massive water wall in the section of the enclosed hangar they used for painting aircraft. It was only to catch airborne dust and was not dealing with anywhere near the amount of dust we would create in a woodwork shop. By memory the wall would have been 40m x 10m.

Mic-d is right, the ability of water to control invisible dust is over rated.

If a mist is sprayed onto submicron dust it won't capture much and it won't be quickly washed out of the air. Try spraying mist into a cloud of smoke and you will see just how effective it is and how much water is needed to get rid of the smoke. The smoke is carried in the air like a gas and just swirls past the water droplets.

The process of dropping water onto a layer of dry sawdust on a floor will inject fine dust into the air. The wet sawdust will temporarily reduce fine dust generation but only until the sawdust dries out. After it rains on dry earth the atmosphere looks clearer because the visible size particles have been washed out of the air but there is still heaps of invisible dust in the air, sometimes even more that before it rained! If it keeps raining the air will get cleaner and the earths surface will be wet so it will generate less dust, so after a while the air will get cleaner still, till the earth dries out.

Originally Posted by BobL

There is no doubt that a 3 grand cyclone and a 1 grand HEPA will be very effective of capturing 99.9% of stuff down to 0.1 micron, 99.95% of stuff down to 0.3 microns and 99.99% down to 1 micron. But you will probably have to change the HEPA filter at least every year.

SHOP-VAC 90671/90672 DISPOSABLE DRYWALL FILTER BAGS cost AUD$29.50 for 2 bags.
• Converts any shop vac into a drywall vacuum
• 2 ply - 95% filtration efficiency at .1 micron
• Inner liner improves filtration durability
• Polybagged , SP+

SHOP-VAC 9033400 Vacuum Cleaner HEPA Cartridge Filter cost AUD$50
• Fits most Shop-Vac wet / dry models, except 1x1, AllAround, FloorMaster, Hang-Up Series. For High Efficiency Particulate Air filtration that's 99.97% efficient down to 0.3 microns. Use for dry pickup only Foam sleeve protects filter from being damaged by larger debris Shop-Vac extensively tests HEPA filters to ensure the highest quality performance and specifications Shop-Vac recommends using a Filter Bag together with the HEPA filter for optimum performance


If I cannot trust ShopVAC's specifications then I may also have to distrust all the 3M, Racal dust mask filter makers as well.
That means everyone must use $1000 Dust masks ?


It may be TOO BOLD to claim the HEPA filter from ShopVac will not filter 99.97% down to 0.3 microns just because it only cost $50.

My former factory had two "class 100" clean rooms for making VLSI chips.
We had to trust Japanese made industrial Vacs with HEPA filters when used inside the "class 100" clean rooms. They do not cost a GRAND.

Originally Posted by reuelt

SHOP-VAC 90671/90672 DISPOSABLE DRYWALL FILTER BAGS cost AUD$29.50 for 2 bags.
• Converts any shop vac into a drywall vacuum
• 2 ply - 95% filtration efficiency at .1 micron
• Inner liner improves filtration durability
• Polybagged , SP+

SHOP-VAC 9033400 Vacuum Cleaner HEPA Cartridge Filter cost AUD$50
• Fits most Shop-Vac wet / dry models, except 1x1, AllAround, FloorMaster, Hang-Up Series. For High Efficiency Particulate Air filtration that's 99.97% efficient down to 0.3 microns. Use for dry pickup only Foam sleeve protects filter from being damaged by larger debris Shop-Vac extensively tests HEPA filters to ensure the highest quality performance and specifications Shop-Vac recommends using a Filter Bag together with the HEPA filter for optimum performance


If I cannot trust ShopVAC's specifications then I may also have to distrust all the 3M, Racal dust mask filter makers as well.
That means everyone must use $1000 Dust masks ?


It may be TOO BOLD to claim the HEPA filter from ShopVac will not filter 99.97% down to 0.3 microns just because it only cost $50.

My former factory had two "class 100" clean rooms for making VLSI chips.
We had to trust Japanese made industrial Vacs with HEPA filters when used inside the "class 100" clean rooms. They do not cost a GRAND.

Don't know what you're really on about here. Did somebody argue that the ShopVacs filter specs are incorrect?
I think Bob's talking about filters that are bigger than a vacuum cleaner filter.
It's not logical to compare the filters you used in a clean room in an electronics factory with those needed for a woodwork setting.

Cheers
Michael

If you already have a DC couldn't you just get a room filter? I'm sure you could find one second hand for less than the price of a Miele anything. Carbatec has them new for like $500 bucks, a lot of money if it's just a hobby but if you're really worried about dust...

I used on all the time, worked a treat.

I like the electrostatic idea though, just get a heap of girls to take polyester jumpers on and off while you're routing...

Berlin