Thread: Fine dust Problem??

Had a bit of a go at this once and it just forms a layer of crud on the surface and very quickly became unusable.

Originally Posted by reuelt

Bill Pentz and his cyclone research & Clear Vue Cyclone does NOT seem to have any real solution for a typical hobbyist woodworker.
"6 inches ducts & 3 HP blowers" is like "using elephants to kill ants".

I think there is a simple solution.

If say our "shop vac" is blowing out fine dust though the HEPA filter, why can't we just connect the outlet to a "snokel" and pass the air though a bucket of water? (Snokel to prevent suck back).

In that case all the "super fine" dusts will just NOT fly around in our shop anymore.

OK woodworkers. What do you think? Is this feasible?

I experimented with that in the 1980s and guess what?

Just bubbling the air through a short path length of water does not capture enough dust and the path length of water needed to effectively capture the dust requires about 3HP of grunt to create the air pressure needed to overcome the water pressure. Yes you can reduced the volume and increase the pressure but then it takes weeks to filter all the air in the shed and you end up making the dust faster than it can be cleared.

The other headache is the air coming out of the water filter is close to 100% saturated with water vapor and makes an absolute mess of the room. Capturing fine wood dust is not an easy task since a minimum air velocity is need to grab fine wood dust at the source.

The simplest solution (not applicable to everyone) is still venting a conventional DC or Shop vac outside your shed.

Thanks Groggy and Bob for info.

POSITIVE THINKING will conclude

based on Bobby's results,
"A running overflowing water system may be required"

Based on Bob,
"Still duct the air outside to avoid high humidity in shop"


Safety Authorities Documents always recommend
"Use water to wet wood dust in order to reduce the likelihood of ignition or dispersion of dust into the air".


So wetting the dust is recommended anyway. Spraying is what the big industry use.


(I presume that the shopvac outlet should have very little dust left having already gone through a mini cyclone + a hepa filter)

Originally Posted by reuelt

based on Bobby's results,
"A running overflowing water system may be required"

Why bother - it won't work unless you use ~3HP and some might call a running overflow wasting a scarce resource.

Based on Bob,
"Still duct the air outside to avoid high humidity in shop"

Err. . . . . if you are going to vent outside, why bother to use a water filter?

(I presume that the shopvac outlet should have very little dust left having already gone through a mini cyclone + a hepa filter)

Err . . . no. 99.9% of shop vacs including so called HEPA vacs create more fine dust than they pick up. The mini-cyclones in them just pick up chips and if you are not spending a couple of grand on a HEPA vacuum cleaner it's a fine dust maker not a fine dust collector. We operate ultra clean air labs and have teste many cheap vacuum cleaners - you basically get what you pay for.

Err. . . . . if you are going to vent outside, why bother to use a water filter?

I am thinking of a possible way of stoping the fine dust from being "air borne" and carried with the wind into our own house and/or the neighbour's house. Why harm the neighbours and/or our own family?

When I wa s factory manager of an electronics factory, we use steam in the room so that charged static particles do not "float" around and destroy the Integrated circuits. It worked very well.

Probably
I guess I can also try passing the vacuum outlet though the 2 unused "evaporative coolers". Modifiy so that the water is filtered.

Idea to to get rid of the fine , small quatity "fine dust" that are health hazards.

Bill Pentz idetified the the problem. Good.

But a hobbyist may have to find other solutions to the identified problem.

Worrying about uncaptured hobbyist dust vented outside is like worrying about whether someone peed beside you in the surf.


Cheers
Michael

Originally Posted by reuelt

I am thinking of a possible way of stoping the fine dust from being "air borne" and carried with the wind into our own house and/or the neighbour's house. Why harm the neighbours and/or our own family?

I have posted far too much on this already.
If you are interested here are a few threads to read on this subject.
1, 2.

Don't know about the rest of you but if I knew a neighbour was venting dust in the direction of my family I would certainly do something about it. Depending on the arrangement of buildings and airflow, the neighbour could easily be pumping that muck into your house.

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.

Originally Posted by Groggy

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.

Groggy, I don't know where your 0.4 micron figure comes from since the dangerous dust is all wood fibres ranging below about 5 microns which every woody using power tools or sandpaper in a suburban setting is already generating and subjecting their family and neighborhood to. The reason that wood dust less than about 0.1 microns is ignored is because woodworking does not generate many particles below this size and because you breathe out just about all the <0.1 micron particles you breathe in. However, this depends on time and size of operations. Lone woodworkers and their neighbors using sandpaper a couple of times a week are pretty safe. A bank of drum sanders operating 40 hours a week will fill the air with the smaller particles - a gas mask is essential for the operator in this kind of environment and some serious shop air filtering is needed for the sake of the neighborhood.

Basic DCs and shop vacs do not capture any sub 5 micron dust. Big Cyclones and air filter units only capture part of this micron range and as people with these devices generally use their shops for longer periods per day they end up dumping similar total amounts of very fine wood dust into their local neighborhood as an occasional woodworker does using no dust collection at all.

What most people do not realize is that the fine dust hangs in the air for hours and the finer stuff for days. It fills sheds and leaks out into the garden forming an invisible hemisphere of itself in the neighborhood until the breezes move it on and mix it into the air.

Even if you run a cyclone and an room air filter, unless you run an air tight room with air locks, some of this fine dust will escape from the shed or every time you open the door. If no dust collection is used then there is no difference between deliberately venting the fine dust outside and letting it hang around your shed like a smog blanket since it will ultimately be redistributed across your neighborhood anyway. In terms of everyones safety it would be better for all if we could use a chimney and lift it higher into the atmosphere but that would not go down too well visually.

Unless woodies are ultimately using very serious $700 - $1000 (99.95% at 3 micron) HEPA filters (that's the price of the filter alone, no motor or fan involved) their fine wood dust is already being ejected and mixed into the neighborhood air - it cannot be seen as it is too small and it cannot be easily identified because suburban air is already ladened with a shyte load of other dust (skin, hair, rock dust, car tyre rubber, ash, etc) in this particle size range. An electron microscope is needed to differentiate the particles and it cannot be done in 5 minutes. The dilution of wood fibres into the atmosphere amongst this sea of other particles is very effective otherwise there would be hell to play well before now. This is my peeing into the ocean analogy which I refer to in my other posts on this subject.

Please bear in mind I an talking weekend warrior here not a commercial operation or an enthusiast who works 7 days a week in their shed - they definitely need to do something about dust but even then not all do.

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.

Originally Posted by mic-d

Worrying about uncaptured hobbyist dust vented outside is like worrying about whether someone peed beside you in the surf.


Cheers
Michael

Yep!

Bobl

Truly excellent series of posts. Most enlightening. I suspect that you are feeling that you have done this topic to death but may I request that you keep posting. I, for one, have learned a lot and continue to learn from your posts. Your professional knowledge in this area and your ability to explain clearly and simply is a boon to us all.

Perhaps you might like to consider posting some photos or diagrams of your system and a Bill Pentz style explanation of the science and the reasons why you designed your system the way you did.

A second issue. SWMBO wanted a new vacuum cleaner and I got a Miele Cat & Dog, but baulked at paying an extra $200 for the model with the HEPA filter. When I went to do the annual filter change the guy in the vac shop simply said - "What type of filter, HEPA or standard - $40 or $20..." The light blue coloured HEPA filter was identical in size and shape to the grey standard filter and simply slotted into the standard model cleaner. It seems that this was the only difference, inspite of the hefty price differential.

Cheers

Graeme

I think we can generally agree on:
Particles below 0.1micron can pass through or is mostly expelled by the lungs.
0.4 is realistically about the best a hobbiest can get to without significant cost.
Above 0.1micron is hazardous to your health.

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."

Without questioning the accuracy of the data you provided, I fail to see the relevance of your post to what I have said Bob. Given that what I have said is essentially someone aiming an exhaust stream from a cyclone over the fence. Assuming they have the sense to filter the large visible stuff out so they don't get caught, they can still be pumping 0.1 to 5micron dust laden air directly at an open window or doorway of a nearby house.

On larger properties where the neighbours are at a safe distance that is not an issue but they were clearly excluded by what I said. For example, If I exhaust my DC in the most convenient place at home, it would be aiming at the neighbour's bathroom and kitchen windows which are only 1.5 and 3m distant from the ideal exhaust point.

Originally Posted by Groggy

I think we can generally agree on:
Particles below 0.1micron can pass through or is mostly expelled by the lungs.
0.4 is realistically about the best a hobbiest can get to without significant cost.
Above 0.1micron is hazardous to your health.

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."

Without questioning the accuracy of the data you provided, I fail to see the relevance of your post to what I have said Bob. Given that what I have said is essentially someone aiming an exhaust stream from a cyclone over the fence. Assuming they have the sense to filter the large visible stuff out so they don't get caught, they can still be pumping 0.1 to 5micron dust laden air directly at an open window or doorway of a nearby house.

On larger properties where the neighbours are at a safe distance that is not an issue but they were clearly excluded by what I said. For example, If I exhaust my DC in the most convenient place at home, it would be aiming at the neighbour's bathroom and kitchen windows which are only 1.5 and 3m distant from the ideal exhaust point.

I just wanted to add that I have two large pleated filters on my dusty that cost a bomb and are supposed to filter 95% of 1micron particles, and seem to do just that, so I don't make a habit of pumping unfiltered air out the window, and depending on the phase of the moon I might agree with either you or Bob. I know this is a precarious postion, as Confucious say, man who walk with one leg each side of fence...

Cheers
Michael

Originally Posted by GraemeCook

Bobl

Truly excellent series of posts. Most enlightening. I suspect that you are feeling that you have done this topic to death but may I request that you keep posting. I, for one, have learned a lot and continue to learn from your posts. Your professional knowledge in this area and your ability to explain clearly and simply is a boon to us all.

Thanks Graeme.

[quote]Perhaps you might like to consider posting some photos or diagrams of your system and a Bill Pentz style explanation of the science and the reasons why you designed your system the way you did.[QUOTE]
I have a 5.2 x 3.6 m shed and I use a 1 HP DC (about to upgrade to 2 HP but need to rewire shed) located outside my shed. My TS, mini lathe, router, beltsander, and drill press are all hooked up via PVC pipe to the DC and I generally use them one at a time. My 19" bandsaw and 10" planer thicknesser cannot fit inside my shed so I use them on the back veranda (have to remove the washing from the washing line first!)

The 1 HP unit is truly gutless (which is why I bought a 2HP unit) and with some activities like ripping longish bits of timber it's obvious the visible dust sprays everywhere so there must be heaps of invisible dust there as well. When I need to undertake extended periods of these activities I wear a Triton Dust Helmet/mask. None of the above will capture the dust at source (at least 3 HP is needed for that which is the best and more expensive possible solution) but here is what I do to minimize my risk. Remember risk is a product of total exposure - concentration x time.

1) Leave the shed door open even in winter - just put on extra clothes.
2) My DC is located outside so I am not recirculating fine dust.
3) Open all DC gates and the run the DC for at least 20 minutes after any dust making activity. This basically means leaving the on after the first dusty activity and turning off after leaving the shed. I also often turn the DC on when I enter the shed. This ensures a constant removal of fine dust (and fumes from welding etc) and a constant supply of fresh air. This is why I think auto switched DCs (DCs that switch on-off with machine use) are a waste of time since the leave the shed full of fine dust.

Is my shed clean? Nope, it's often got a cm layer of sawdust on the floor. This by itself will generate fine dust since it degrades slowly and everytime I walk on it it pumps fine dust into the air. Every now and then I use a vacuum cleaner to clean up. I start by turning on the DC and opening all gates. Then I vacuum up the chunks and leave the DC on for an hour or so afterwards to get rid of the huge amounts of suspended fine dust generated by the vacuum cleaner inside the shed. I generally do this as a last activity of the day and if I was serious I would use a mask during this activity. Apart from real HEPA vacuum cleaners, most will generate more fine dust than they pick up.

The idea of the 2HP DC is will remove suspended fine dust quicker and replace the fresh air faster.

A second issue. SWMBO wanted a new vacuum cleaner and I got a Miele Cat & Dog, but baulked at paying an extra $200 for the model with the HEPA filter. When I went to do the annual filter change the guy in the vac shop simply said - "What type of filter, HEPA or standard - $40 or $20..."

The Miele Cat and Dog units with the HEPA filter still only contain what I would call a semi-serious HEPA filters. These units contain class 12 EN 1822 HEPAs which are 99.5% efficient at an unspecified micron rating (probably 0.5 microns) whereas true HEPA filters must be able to filter out 99.97% of airborne particulates 0.3 microns or larger. While this does not sound like much of a difference once again it is a concentration multiplied by exposure time and if a person is allergic to whatever it can be sufficient to create a problem. The best HEPA filtered vacuum cleaners are those use to clean "ultra clean" laboratories and capture 99.995% of dust at 0.3 microns or larger. We last bought one in 2004 and I think it cost $2500. The replacement filter costs $500?. Even this unit makes some dust.