Thread: Air Filtration for Workshop

Originally Posted by Putty

Hi all,
Like a lot of us I work out of my double garage, and despite my best intentions (and dust extraction/control equipment) the dust still tends to get the better of me.
Mostly the fine powdery dust which settles on shelving, tools, bench, etc. .

Before you buy an air filtration unit, OHS wise it's considered best practice to tackle these issues.

1) Failure to use dust extraction for all tasks that generate dust.
Some sort of lock out device that prevents machines being used unless the dust extractor is on and connected to dust making machine.
This is hard but not impossible for power tools

2) Dust extractor not powerful enough, and/or ducting not large enough to fully capture dust source
Up to 1000 Cubic ft/min is needed to capture fine dust from machines. This cannot be achieved using 4" ducting and 6" ducting is needed

3) Machines are too choked
Machines with 2" and 4" ports are pretty useless at collecting all the fine dust that they generate and prevent capture at source.

4) Using the dust extractor itself inside a shed.
A dust extractors leak so they are best located outside a shed, or enclosed in an airtight enclosure and vented outside the shed.

Until these are addressed, air filtration units will struggle to keep the dust down.
Even once those issues are addressed, residual dust can usually be managed using low cost ventilation.
Something like a couple of bathroom fans would be a start but there are more efficient and quieter options out there.
While ventilation/fresh air is a better health option it does not remove the dust from the fresh air being brought into a shed which can be a problem when applying finishes.
Room air filters are useful for removing dust from the air before applying finishes.

I have a hospital operating theatre grade room air filter in my shed but because I have addressed the above issues I only use it when applying finishes.

OK, I'm satisfied with the performance of my 2300cfm dusty which is only ever connected to one machine at a time on a ~1m length of hose.

I use an air compressor to blast residual dust generated from (mostly) my belt sander and router sled down to where the dust extractor is so I can then vacuum it up. Don't worry I use a an A1+P2 respirator at all times. Would an air filtration device help catch this dust in mid air as it hangs on the way down to the extractor?

Cheers,

Anthony

Originally Posted by Putty

OK, I'm satisfied with the performance of my 2300cfm dusty which is only ever connected to one machine at a time on a ~1m length of hose.

I use an air compressor to blast residual dust generated from (mostly) my belt sander and router sled down to where the dust extractor is so I can then vacuum it up. Don't worry I use a an A1+P2 respirator at all times. Would an air filtration device help catch this dust in mid air as it hangs on the way down to the extractor?

Cheers,

Anthony

"Satisfied with the performance of the 2300CFM" DC usually means it collects the saw dust you can see (ie chips) but is not collecting anywhere near enough of what's eventually settling out every where in the workshop ie the fine dust you can't see.
Just because it says 2300 CFM doesn't mean much if you are using 4" ducting since the most it will then suck is ~400 CFM which means it leaves a lot of fine dust behind.
The best way to reduce this is 6" ducting and collect as much air as possible which can only be done with 6" ducting.
Also if the DC is inside the shed there will always be fine dust everywhere.

RE: Compressed air
Using compressed air to direct visible dust is one thing but to try and direct invisible dust is like herding cats and will just end up spreading the invisible dust even further all over your workshop.
An air flitration unit will catch some of that dust but it won't be fast enough or widespread enough to catch it all so you will still have dust settling out in the furthest reaches of the shed..
A couple of bathroom fans that vent the workshop while the dust is being made and sometime thereafter can be just as effective for about 1/10th the cost.

Seriously, trying to catch the dust after it has escaped collection is a no win task - it's best to set things up properly to begin with - also then you would never need to wear a respirator again.

OK, we might be talking about two different things. There's nothing invisible about the dust I'm talking about. I accept that on an atomic level there will be invisible to the naked eye dust particles around the shop, and without improvements to the overall workshop they will long stay there.

I'm talking about fine powdery dust that settles in patches around the place. On machinery, on shelving, etc. When it is either blasted with an air compressor or swept with the broom, some of it inevitably flies into the air and hangs for a time before resettling.

If I have such a thing as an air filtration unit turned on, as the visible powdery dust flies into the air, would it not be sucked up by the intake?

This same dust gets eaten by the dust extractor, it does a great job doubling as a vacuum, but that involves disconnecting one of the machines, attaching the big gulp end and running around the floor sucking it all up. Would the air filtration unit not act as a sort of passive accumulator of this dust as its in the process of being flung into the air?

Exhaust fans are out because I live in the suburbs and am not going to share my hobby with my neighbours and their clothing/belongings on that level.

that fine dust that eventually settles out of the air is typically suspended in the air and invisible (or nearly) to the naked eye, when you are creating it.

As Bob says - collect as much as you can where you make it (that means 6 inch collector, not stock 4 inch) so that you have less of a problem to deal with, don't assume 2300cfm means anything, and read the numerous posts here about how you can improve things.

Originally Posted by poundy

that fine dust that eventually settles out of the air is typically suspended in the air and invisible (or nearly) to the naked eye, when you are creating it.

As Bob says - collect as much as you can where you make it (that means 6 inch collector, not stock 4 inch) so that you have less of a problem to deal with, don't assume 2300cfm means anything, and read the numerous posts here about how you can improve things.

again read this again, implant it on your brain, seriously think of your LONG TERM health and your poor family having to watch you cough up shoit cause you did not take precautions in the first place.

Originally Posted by Putty

OK, we might be talking about two different things. There's nothing invisible about the dust I'm talking about. I accept that on an atomic level there will be invisible to the naked eye dust particles around the shop, and without improvements to the overall workshop they will long stay there.

I'm talking about fine powdery dust that settles in patches around the place. On machinery, on shelving, etc. When it is either blasted with an air compressor or swept with the broom, some of it inevitably flies into the air and hangs for a time before resettling.

That is also what I am talking about. It starts out as invisible dust so if it's vented while its been made or soon thereafter your neighbours won't see it, Some of this dust is so fine it will pass though a standard room air filter anyway and go round around inside your shed.
THEN
Over time it settles out of the air and agglomerates (absorbs water from the atmosphere, swells and combines/sticks together with other fine dust to form a mix of visible and invisible dust) and this is what you're seeing settling on surfaces.

If I have such a thing as an air filtration unit turned on, as the visible powdery dust flies into the air, would it not be sucked up by the intake?

Some will but most will just redistribute itself around the shed. A compressed air blast will not direct this dust. As soon as it is blasted with air especially the invisible dust flies off all over the place. Invisible dust acts more like a gas (think bad smells like a fart) if the room is full of fart smell a compressed air bast will not be very effective at directing the smell out compared to a an exhaust fan.

This same dust gets eaten by the dust extractor, it does a great job doubling as a vacuum, but that involves disconnecting one of the machines, attaching the big gulp end and running around the floor sucking it all up. Would the air filtration unit not act as a sort of passive accumulator of this dust as its in the process of being flung into the air?

Yes it will help - but like I said for 1/10th of the price you can use ventilation which is better for you.

Using a DC as a vacuum is fine for chips but it is not collecting enough air to collect the fine/invisible dust suspended in the air.

Exhaust fans are out because I live in the suburbs and am not going to share my hobby with my neighbours and their clothing/belongings on that level.

The neighbours won't see a thing because the dust is invisible.
My shed is also "in the suburbs" on small inner city block (1.5km from the CBD). I've had my DC venting outside since 2011 and my very fussy "over the back" neighbour has his pool and spa just over our back fence right next to where my DC vents to the atmosphere - if dust or noise was an issue he would have knocked on my door and complained loudly many years ago.

Just in case you are unaware, the 270 mg of super fine (agglomerate) dust in this soft drink bottle top is enough to contaminate four 6 x 4 x 2.7 m sheds above the recommended OHS level.
Softdrinkdust.jpg

Originally Posted by Tonyz

again read this again, implant it on your brain, seriously think of your LONG TERM health and your poor family having to watch you cough up shoit cause you did not take precautions in the first place.

Family not impacted - dust never makes it into the house. I wear a respirator which I religiously maintain.

Good alarmist rant tho 10/10.

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Originally Posted by BobL

The neighbours won't see a thing because the dust is invisible.

100% not invisible. Collecting and exhausting it during production cannot change it's physical makeup, it will just mean that rather than settling in my workshop it will settle outside. In the ACT we don't have huge blocks, and bugger all space between the workshop and the neighbours place. It *will* settle outside, on their property.

Regarding going from 4" (which as far as I can tell is industry standard) to 6", my dust extractor and all machines are fitted for 4". Even if I do increase the throughput of the hosing itself to 6" it will still be bottlenecked at the source and at the end. Does fitting a larger diameter hose in these circumstances actually make any difference? If so, how?

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Originally Posted by Putty

Family not impacted - dust never makes it into the house. I wear a respirator which I religiously maintain.

Good alarmist rant tho 10/10.

Relying on a respirator is better than nothing but in OHS terms it's a poor choice

Unless it's collected while it's being made, because woodies are so close to wood dust sources and they often get the dust directly sprayed onto them they carry around significant amounts of fine dust. Even after the dust has been made significant amounts of fine wood dust will continue to deposit all over a woodies clothes, skin and hair. In a poor dust collection situation the amount of dust on a woodie is sufficient to contaminate a room or two so they easily exceed the OHS limit. The person most affected is the woodie because after the respirator is removed the human body constantly acts like a chimney and body heat and clothing flex will continuously puff small amounts of fine fine dust off the clothes and channel it up past a woodies nose. If the woody touches or brushes past anyone anyone the dust will be transferred to them. Not that significant for others if it's only weekend warrior stuff and no one has an allergy to wood dust.

Here's a example that happened on the weekend that shows how quickly and far something can spread.
Last weekend a few family members gathered together to start clean out deceased FIL's shed.
Mostly junk but a few small treasures, including several small acetylene miners lamps.
I had seen them before and know how they work, they typically contain a few hundred grams of calcium carbide(CaC2) powder onto which water it dripped which generates acetylene which is burned to provide light.
I carefully opened one up to see if it had CaC2 and it did, (FWIW these lamps would have been last used in the 1930's) so I carefully screwed the lid back on.
The lid would have been off for about 15 s at most.
We continued cleaning up but after ~15 minutes my arms started itching, also my son started itching, then my nephew and 3 yr old grandson who didn't even even enter the shed but my son had briefly played with on the back lawn .
I thought at first it was something else like fibre glass but we never saw any and then it dawned on my that the itch started after I opened the miners lamp.
In short, that brief opening puffed enough fine CaC2 into the air to affect a number of people including one who was not even in the vicinity.
I then looked up the MSDS for CaC2 and sure enough it's classed as skin irritant.

There are two primary health issues involved with wood dust - one is cause by direct long term exposure like nose and upper respiratory tract cancers. These are more likely when woodies are exposed to lots of wood dust for extended periods ie not that likely for a weekend warrior. The other is the likelihood of developing an allergy, also more likely in high exposure/lengthy periods situations BUT can also be triggered in some people by a very small dose. If anyone really likes wood working this could be more than just annoying.

Then, apart from wood dust, there is ALL dust. In 2017 ALL dust was moved from the 8th leading cause of death in the world to the 5th leading cause of death. Dust is now considered a major contributor to non-respirator diseases like strokes and other coronary cause of death.

Originally Posted by BobL

Relying on a respirator is better than nothing but in OHS terms it's a poor choice

Unless it's collected while it's being made, because woodies are so close to wood dust sources and they often get the dust directly sprayed onto them they carry around significant amounts of fine dust. Even after the dust has been made significant amounts of fine wood dust will continue to deposit all over a woodies clothes, skin and hair. In a poor dust collection situation the amount of dust on a woodie is sufficient to contaminate a room or two so they easily exceed the OHS limit. The person most affected is the woodie because after the respirator is removed the human body constantly acts like a chimney and body heat and clothing flex will continuously puff small amounts of fine fine dust off the clothes and channel it up past a woodies nose. If the woody touches or brushes past anyone anyone the dust will be transferred to them. Not that significant for others if it's only weekend warrior stuff and no one has an allergy to wood dust.

Here's a example that happened on the weekend that shows how quickly and far something can spread.
Last weekend a few family members gathered together to start clean out deceased FIL's shed.
Mostly junk but a few small treasures, including several small acetylene miners lamps.
I had seen them before and know how they work, they typically contain a few hundred grams of calcium carbide(CaC2) powder onto which water it dripped which generates acetylene which is burned to provide light.
I carefully opened one up to see if it had CaC2 and it did, (FWIW these lamps would have been last used in the 1930's) so I carefully screwed the lid back on.
The lid would have been off for about 15 s at most.
We continued cleaning up but after ~15 minutes my arms started itching, also my son started itching, then my nephew and 3 yr old grandson who didn't even even enter the shed but my son had briefly played with on the back lawn .
I thought at first it was something else like fibre glass but we never saw any and then it dawned on my that the itch started after I opened the miners lamp.
In short, that brief opening puffed enough fine CaC2 into the air to affect a number of people including one who was not even in the vicinity.
I then looked up the MSDS for CaC2 and sure enough it's classed as skin irritant.

There are two primary health issues involved with wood dust - one is cause by direct long term exposure like nose and upper respiratory tract cancers. These are more likely when woodies are exposed to lots of wood dust for extended periods ie not that likely for a weekend warrior. The other is the likelihood of developing an allergy, also more likely in high exposure/lengthy periods situations BUT can also be triggered in some people by a very small dose. If anyone really likes wood working this could be more than just annoying.

Then, apart from wood dust, there is ALL dust. In 2017 ALL dust was moved from the 8th leading cause of death in the world to the 5th leading cause of death. Dust is now considered a major contributor to non-respirator diseases like strokes and other coronary cause of death.

Great points - pretty much why I decontaminate myself with the air compressor all over and take off my dust jacket and apron before I remove my respirator and step inside.

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Originally Posted by Putty

100% not invisible. Collecting and exhausting it during production cannot change it's physical makeup, it will just mean that rather than settling in my workshop it will settle outside. In the ACT we don't have huge blocks, and bugger all space between the workshop and the neighbours place. It *will* settle outside, on their property.

The only time this will happen is if there is no wind.
Fine dust rises like smoke as it and shed air is slightly warmer than its surroundings and stays suspended for many minutes and even hours.
Even a 0.5km per hour breeze will see it 500 m away in an hour - by then, the concentration of any wood dust will be so dilute it will not be discernible from ordinary dust.
I note the average wind speed for Canberra this month at 9am is 13kph and at 3pm it ia 25kph - under those conditions your neighbours won't see jack.
If you read my previous post about my inner city suburb workshop and fussy neighbour - but I do collect most of it at source.

Regarding going from 4" (which as far as I can tell is industry standard) to 6", my dust extractor and all machines are fitted for 4". Even if I do increase the throughput of the hosing itself to 6" it will still be bottlenecked at the source and at the end. Does fitting a larger diameter hose in these circumstances actually make any difference? If so, how?

Industry is still operating with 1960's standards which are in dire need of an update. At least the Europeans have 5" but in some situations this may not be enough.

Yep the dust ports on machinery do need to be opened up otherwise it won't help much.
There are heaps of posts on this forum to you how to do this.
I've visited many sheds and workshops as part of my free dust advisory service and opening up machinery ports is one of 3 key recommendations.
The other two being a powerful enough DC and the use of 6" ducting.

Originally Posted by Putty

Great points - pretty much why I decontaminate myself with the air compressor all over and take off my dust jacket and apron before I remove my respirator and step inside.

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That gets some of the fine dust off the outside but the insides of your clothes will also be full of fine dust. The human body acts like a pump whereby movement against clothing sucks fine dust inside your clothes. You have to remove all your clothes as well.

Originally Posted by BobL

That gets some of the fine dust off the outside but the insides of your clothes will also be full of fine dust. The human body acts like a pump whereby movement against clothing sucks fine dust inside your clothes. You have to remove all your clothes as well.

OK. I guess I'm not sure where to go with this from here, I feel like you're talking about some fairly extreme scenarios here - which I acknowledge are a problem - just not a problem I'm concerned with personally. I'm more concerned about just keeping the shop relatively tidy.

I'm not after a 'safe by today's WHS standards safe' workplace, and as I see my GP regularly for other matters and he's happy with the state of my respiratory system (which was pretty knackered a long time before I took up woodworking - just unlucky I think), I'm just trying to create an efficient environment to work in.

My 2300 cfm dusty hauls all kinds of when turned on - I have many full bags of chips (and dust for the record) to show for it. I acknowledge that it is not sufficient to control the invisible dust to which you are referring, but to be honest if it indeed invisible I'm not too worried about it.

Something is going to kill me one day. I doubt given my lifestyle that it's going to be related to the dust I generate when woodworking, but I acknowledge that it's a possibility.

I also acknowledge that by my logic you could get hit by a car any time you cross the road, but that doesn't mean you shouldn't take necessary precautions. I do take necessary precautions when I cross the road (I look both ways, I calculate my ability to move quick enough to avoid being hit, and I go for it). I acknowledge that it would be safer to go to a set of lights, press the button, wait for all traffic to come to a complete stop, then cross, but I'm not willing to do that.

I take the same approach to woodworking. I acknowledge that there are better control measures I could take to prevent dust inhalation. I take as many as I'm willing to and I accept the risk from that point on.

I'm not after a safe environment, I'm after a visibly clean one.

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