Thread: Room air filter - Yes or no?

Originally Posted by Huon pine fan

My workshop (total area) measures approx. 6m x 12m. My machinery comprises a Laguna 14" bandsaw, Minimax C26 combination saw, Jet oscillating belt sander and router table with Triton router. I hook these up to my Carbatec DC1200P 2HP dust extractor which seems to do reasonable job.

Comments on the above
1) A stock 2HP might manage the chips but it simply wont handle the fine dust output of those machines. Even a modified 2HP DC (one that uses 6" ducting) should really be used in a small shed with short ducting runs
2) Given the size (72m^2) of your shed you will need 6" ducting and at least 4HP/15" impeller DC to really control fine dust in that situation.
3) all DCs leak so the DC needs to be located, or enclosed in an air tight cupboard inside the shed and vented, outside then shed.
4) The DC and machinery must have unrestricted 6" path way the the air flow path.

In addition I have a Festool Capex sliding compound saw that is permanently hooked up to a Festool dust extractor as well as assorted Festool tools which I connect to another Festool dust extractor when in use.

Even good quality vacs cannot collect all the fine dust emitted from power tools - plus all vacs eventually leak. If you you really want to control fine dust from power tools your shop vac should also be located, or enclosed in an air light cupboard and vented, outside then shed.

I have read that room air filters are a very worthwhile addition. I would welcome some input/commentary on the desirability or otherwise of these. As I understand it I would need to string it up from the ceiling. As I have a steel shed I am guessing that this would mean from the roof purlins. The shed door is typically shut, certainly in winter, in hotter weather open anything up to 3m (sliding door).

Room air filters (RAFs) are slow at removing dust from the air and usually cannot keep up with operating machinery in removing dust from the air. This means while machines are running the fine dust build up faster than the RAFS can clear it. This is why it's better to collect the fine dust at source with a powerful DC before the fine dust escapes into the rest of the shed.RAFs are best used in situations when machines are small, usage is light and intermittent, or when ALL dust (not just wood dust needs to be removed from there such as would be needed to apply fine finishes. I have an RAF in my shed and I only use it when applying finishes.

If you do the 2), 3) and 4) things I suggest above you will not need an RAF for anything other than application of finishes.You would be better off putting the $ towards a better DC and 6" ducting.

For small sheds (yours is too large) an alternative to RAFs is forced ventilation, For the price of an RAF one can purchase ventilation fans that will move a lot more air and dust into and out of the shed. Of course being in Melbourne you can expect to freeze from time to time, but you will anyway if you employ points 2) - 4) above.

Originally Posted by Huon pine fan

I have a Festool Capex sliding compound saw that is permanently hooked up to a Festool dust extractor as well as assorted Festool tools which I connect to another Festool dust extractor when in use.

Are you using the standard advise 27mm hose with that? If so, then one of the best things you can is change it to a 36mm hose. The 27mm attachment has a dia of 19mm but the 36mm is just that. So it is >3 times the cross-sectional area. I also added a 100mm outlet going into a 125mm hose to a 2HP DC at the back of the cut which makes a very significant difference to the amount of dust left on the table (I hope that also translates to more fine dust being captured, although a proper dust shroud for the mitre saw is best).

I forget the number of cuts in these tests but i think it might have been 30 each through the same boards.

With just a Festool vac and 36mm hose:




And with the vac plus the 2HP DC running:




Note that the air flows don't particularly compete with each other - one goes up the spout at the back of the blade and the DC flow (slower but higher volume) just peels off to the right a little bit. As much as I can I have the 100mm touching the black shroud, but it's not always possible.

Thanks Bob, a very helpful amount of information. A few questions/points
1. I don't know if it changes the thinking but 1/3 of the shed is utilised for timber storage and an old car. Of the 2/3 that I work in a reasonable amount of space is lost to benches, further timber storage, cupboards and other machinery.
2. Excuse the ignorance but what exactly do you mean by unrestricted 6" path way? No bends?
3. Relocating the DC outside might be somewhat of an exercise, room is no issue however it would be at the far end of the shed so pretty much 5m (in straight line) from the nearest piece of machinery. Can the on/off switch be located inside the shed?
Thanks again

Thanks FF
Yes, I only have the standard hose and yes there is plenty of sawdust at the back of the saw. The PVC ducting idea certainly has merit so I will look into if it is feasible to add the additional extraction as where I have the saw located might preclude the idea.

Originally Posted by Huon pine fan

My workshop (total area) measures approx. 6m x 12m. My machinery comprises a Laguna 14" bandsaw, Minimax C26 combination saw, Jet oscillating belt sander and router table with Triton router. I hook these up to my Carbatec DC1200P 2HP dust extractor which seems to do reasonable job. In addition I have a Festool Capex sliding compound saw that is permanently hooked up to a Festool dust extractor as well as assorted Festool tools which I connect to another Festool dust extractor when in use.
I have read that room air filters are a very worthwhile addition. I would welcome some input/commentary on the desirability or otherwise of these. As I understand it I would need to string it up from the ceiling. As I have a steel shed I am guessing that this would mean from the roof purlins. The shed door is typically shut, certainly in winter, in hotter weather open anything up to 3m (sliding door).
Thanks

I have a smaller shop (6 x 9), the usual Festool vac and tools, and a few more machinery that generates a lot of fine dust, such as: a double belt sander at 1100mm wide and a double mitre saw. my extractor is a bigger extractor (4kw bag house) with stainless steel ducting at 10 inch trunks.

I have the room air filter, I do switch it on - sometimes. did it make any difference to air quality? I dont know, I always wear full face mask.

If you have extra few hundy to play with and you feel better with it installed, then do it,

or, like Bob pointed out, spend it on your ducting.

Originally Posted by Huon pine fan

Thanks Bob, a very helpful amount of information. A few questions/points
1. I don't know if it changes the thinking but 1/3 of the shed is utilised for timber storage and an old car. Of the 2/3 that I work in a reasonable amount of space is lost to benches, further timber storage, cupboards and other machinery.

Unless this space is sealed/sectioned off right up to the ceiling either by a hard wall or good plastic curtains then the fine dust will enter that space and accumulate and need to be cleared out. Benches cupboards storage etc don't count. It's more the total working area than the volume that counts because its this area determines the lengths of ducting runs. I don't recommend even a modified 2HP DC use 6" ducting runs longer than about 3m (ie 10m^2 workspace) for a 3HP ducting runs should be <6m. If your runs are longer than this then a 4HP DC is really needed.

2. Excuse the ignorance but what exactly do you mean by unrestricted 6" path way? No bends?

No problem - better to ask than go uninformed. By "unrestricted" I mean adding vents into machine cabinets so that air carrying dust can get out. If there are no vents then little dust will be removed. This is a problem for many even expensive machines.

3. Relocating the DC outside might be somewhat of an exercise, room is no issue however it would be at the far end of the shed so pretty much 5m (in straight line) from the nearest piece of machinery.

You will need a bigger DC to do this.

Can the on/off switch be located inside the shed?

Yes.

Sounds like you need a bigger DC more than you need a RAF.

Thanks once again Bob.
The car/timber storage area is not sealed off in any way. To put the DC outside would entail an approx 2m rise to the high point of the roof before entry and then approx 5m run with a drop of about 3m down to the saw. The bandsaw, depending on where I move it to work might be another 2m along the roof before a 3m drop. Both the router and the oscillating sander could be serviced by the same point going to the saw.
Does this change any of your advice?
Brands I should be considering?
Much appreciated

Originally Posted by Huon pine fan

Thanks once again Bob.
The car/timber storage area is not sealed off in any way. To put the DC outside would entail an approx 2m rise to the high point of the roof before entry and then approx 5m run with a drop of about 3m down to the saw. The bandsaw, depending on where I move it to work might be another 2m along the roof before a 3m drop. Both the router and the oscillating sander could be serviced by the same point going to the saw.
Does this change any of your advice?
Brands I should be considering?
Much appreciated

The vertical runs "down" don't count as the sawdust will fall under gravity. It's the upward and horizontal that count so you have about a 7m run to contend with. A 2HP will still move air and saw dust over this distance its just that I'd rather do this with a 3HP DC rather than a 2HP.

I don't like to recommend particular DC brands as I don't have enough direct experience with the newer ones.

The new Timbecon and Carbatech models are powerful enough you just need to make sure they have a 6" intake at the rntry to the DC impeller although it's no biggie if you have make one.
I know the Timbecon 3HP models have a 6" inlet.

The one I have is the older single phase version of this one.
https://www.carbatec.com.au/dust-con...e-ct-oo3vb-3ph.
The latest model is 3Phase and is quite expensive even when its on special - it has an 8" inlet so a 6 - 8" adapter is needed.

If you are on a tight budget then the following might suit as it's on sale ATM
https://www.machineryhouse.com.au/W329#product-tabs
I have some familiarity with it, it's an old design but has a 6" inlet and would do the job.

I'm not sure if you have any expansion plans for you workshop but for that size shed if you can afford it a Clearvue cyclone would be the go and you could expand as much as you like into that space.

Since we added RAFs at work there's been a dramatic improvement in air quality, but it still doesn't solve the problem at the source

Thanks Bob.
I don't have access to 3 phase and I have no expansion plans. I would struggle to stretch my budget to a Clearvue. The 3hp Timbecon unit seems to be reasonably priced alternative. I will do some more detailed planning into ducting, fittings, etc.

Originally Posted by Huon pine fan

Thanks Bob.
I don't have access to 3 phase and I have no expansion plans. I would struggle to stretch my budget to a Clearvue.

Sure it's a common problem.

The 3hp Timbecon unit seems to be reasonably priced alternative. I will do some more detailed planning into ducting, fittings, etc.

Unless you mean the Timbecon FM 2900, the Hare and Forbes DC7 is the same as the Timbecon FM400 and costs ~$70 less than the Timbecon Unit.

Based on the (sometimes wrong) assumption that more is better then I would tend to favour the FM2900.
In regards to a question I asked earlier about having a remote stop/start, is it simply a matter of removing the switch from the machine and then running a lead from the unit to an appropriate place inside the shed where the switch would be remounted?

Originally Posted by Huon pine fan

Based on the (sometimes wrong) assumption that more is better then I would tend to favour the FM2900.

The specs/numbers provided by manufacturers are somewhat meaningless.

It is highly unlikely that the FM2900 generates 22.5" of water column pressure. If it could it would be screaming like a banshee and would be unbearable. At that vacuum a 1m long piece of 100mm flexy would have a force on it of around 180 kg and it would be in danger of collapsing.

If it was 22.5" the impeller should be able to move over 4000 CFM though its 8" opening but the claim is only for 2900 CFM

Even the 2900 CFM is fantasy. Its a number generated for just the impeller using an incorrect Australian standards test that over estimates the flow by ~30%. teh test is performed without any filter bags or any ducting attached to the DC,. In short - its bollocks

The hard nosed reality is that a 3HP can at most move about 1250 cfm though a short 6" duct. The exact number is dependent on the pressure curve of the impeller but the basic performance is a limitation of the duct diameter. A 4HP with a suitably sized impeller can move about 1400 CFM and a 5HP about 1450 through the same size duct.

The next guide to performance would be the diameter of the impeller since this usually determines the amount of air it can pull under load.
I know the DC7 only has a 12" impeller - I am unsure of the diameter of the FM2900 but it won't be much more because a 3HP simply cannot drive a much bigger impeller.

Despite this the FM2900 is probably a superior machine but whether its worth $500 more is debatable.

So don't believe any air flow specs on these machines - maybe ask here first.

In regards to a question I asked earlier about having a remote stop/start, is it simply a matter of removing the switch from the machine and then running a lead from the unit to an appropriate place inside the shed where the switch would be remounted?

Yes

I know Bob is always on about big ducts and lots of air flow ..... and for most of us unrealistic targets...... however.

There are some simpler easier and cheaper options that while not ideal ...... will be way better than what you have and will be better than a room air filter which will do bugger all if you have your extractors inside.

1/ if you can get your extractor/s outside of the air space that you are working in .... either actually outside, or boxed inside and discharging outside ...... you will dramaticly improve your air quality ... more than anything else.

2/If you rearange your workshop, so dust extraction is your priority, you can avoid long runs of pipe.
By placing your machines to best advantage near a wall, you can avoid ALL the ups and downs and run the duct across the floor.

3/ You can get considerable improvements in flow, by replacing as much flexible pipe as you can, with standard 100mm PVC pipe and keeping the runs as short as possible.
For example ... my saw bench ( bottom connection)originally ran about 3 meters of corigated 100mm flexible pipe to the dust extractor .... it now runs about 1 meter of straight 100mm PVC sewer and less than a foot of flexible where it enters the extractor ...... let me tell you there is a dramatic difference in air flow .... AND I did not need to butcher the extractor or the sawbench. ..... standard 100mm fittings are used.

4/ you can also get dramatic improvements, by working on your machines and how they capture dust ...... I stuffed the gaps between the table and the case of my saw bench, with foam ...... this cause much more airflow past the sawblade ...... sometimes I see dust fly away from the blade, do a u turn and go down the hole. ... I have dome major works on my overhead guard on my saw bench ... it has gone from a 2 inch hose all the way to the extractor ..... to 2 x 3 inch hoses onto the guard and 100mm PVC most of the way to the extractor.

Yeh I know Bob means well ...... and i the ideal world, that is what we should do.

But most workshops are spewing dust into the air at a Phenominal rate ........ this can be dramaticly reduced ... like orders of magnitude ....... by some simple and not too expensive methods.

cheers