Workshop extraction

[will1983]

Hi,

In the ever ongoing quest to improve the air quality in my workshop I am thinking about fitting one of these extractor fans.
https://powerstarelectricals.co.uk/indu ... -782-p.asp

I have a couple of fairly large windows in one wall but the frames are shot so they need tearing out and replacing. In an effort to maintain some security I wont be fitting windows in their place. I plan to make a frame the size of the opening and another smaller one inside that to carry the fan unit.

The inside face would be clad in OSB and the outside in feather board cladding with some rockwool between. The exterior face of the fan would be covered with one of these.
https://powerstarelectricals.co.uk/meta ... 1019-p.asp

So has anyone else had any experience of these fan units? The m3/hr ratings on the company's website look a little on the optimistic side to me and I can't find a fan curve graph.

Apparently a 12" unit will shift 3505m3/h which with a workshop (empty) volume of 59m3 should give a turnover of 59 times per hour, so about once a minute.

I think that should be plenty, what are everyone's thoughts?

Oh before anyone else mentions it I already have a big HVLP extractor for my fixed machines and a LVHP vacuum for small hand held power tools. These are very good and collect most of the muck at source but there is always some very fine material not captured, this floats about in the air and then settles on everything. I also do quite a bit of spraying with a Graco airless so I'm hoping the extractor fan should suck all this fine dust and any overspray out before it has a chance to settle onto nice freshly painted surfaces.

TIA Will

 

[Selwyn]

It will be cold!

 

[will1983]

There's no heating in there anyway so it won't make any difference.

 

[Yosarian]

I've got a much smaller workshop and a smaller extractor fan, but the same principle, although for me it's a theoretical air change every 5 minutes. I feel that it does help, although have no measurements to back it up. Have you considered having the fan on a timer, so it's runs for a period of time after you leave the space?

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[will1983]

Thanks Yosarian, do you still get that fine layer of dust on everything or not?

 

[Yosarian]

Thanks Yosarian, do you still get that fine layer of dust on everything or not?

Yes I do. The fan doesn't create a (noticeable) breeze across the room, so larger particles will drop out of suspension. But even if some air is being cycled, it presumable helps with the finest of particles.

I suppose you could test what it might be like by running you HVLP extractor with nothing connected, and the hose in the fans location. Wouldn't that suck a similar-ish volume?

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[will1983]

I do sometimes do that to clear the air when I'm using a tool that I cannot connect the vacuum to and it does work to a point. However the HVLP is a centrifugal fan and only rated to 1000m3/hr. These are radial fans which even if they are over egging the output figures are 3000m3/hr +.

I'm going to buy one and see what happens, at the very least it'll help the paint dry faster when I'm spraying.

 

[will1983]

What diameter extractor have you got Yosarian

 

[Yosarian]

What diameter extractor have you got Yosarian

150mm. My HVLP extractor is 2500m3/hour, but is much noisier so I don't run it continuously.

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[sunnybob]

Something often forgotten when discussing fan air movement is "what air are you moving"?

If you have a sealed room, with a large fan at one end pushing air out, how is air going to get back in so that it can be pushed out again? Overlooking this is why so many people complain fans dont perform to spec.

Fans are rated for movement in still open air. They are NOT suction devices trying to collapse the room.
Have an equal or larger sized opening the other end of the room, and see that air move then! Of course, that makes the room REALLY cold, so normally a compromise is needed.

The really best way to remove fine dust in a smallish room is to have a ceiling mounted recirculating filter , and to change or clean the filters regularly.

 

[will1983]

Hi Bob, thank you for your reply.
I have considered the flow in - flow out issue.

My intention is to install the fan in the window opening located near the front of the workshop. My spraying area is located towards the rear adjacent to the pedestrian door which is almost always left open when I'm in there.

My theory is that this will allow the evacuated air to be replaced with fresh clean air through the doorway and create a through flow. The additional advantage to this should be that the dust and overspray would be moving away from the painting area.

If this theory works in practice I hope to be able to operate my table saw etc whilst painted parts are drying on the racks without contaminating them.

 

[Yosarian]

Yes I agree about providing an air inlet. I always have the door open while I'm working, but do close it and leave the fan running. Perhaps I should add some vents at the opposite end to the fan to let some more air in.

I've got a Record AC400 air filter, but it only filters down to 1 micron. I couldn't find any (at the time) that filtered smaller.

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[will1983]

I couldn't find anything that would give anything better than 1 micron either.
As my neighbours are pretty easy going and the workshop isn't heated anyway that's why I'm looking at this option.

I'm going to give it a go and just see what happens. I might order a pleated filter to and see if placing it in front of the fan catches some of the dry fall material before it gets shot outside.

 

[sunnybob]

Hi Bob, thank you for your reply.
I have considered the flow in - flow out issue.

My intention is to install the fan in the window opening located near the front of the workshop. My spraying area is located towards the rear adjacent to the pedestrian door which is almost always left open when I'm in there.

My theory is that this will allow the evacuated air to be replaced with fresh clean air through the doorway and create a through flow. The additional advantage to this should be that the dust and overspray would be moving away from the painting area.

If this theory works in practice I hope to be able to operate my table saw etc whilst painted parts are drying on the racks without contaminating them.

How dust free is the air coming in through the door?, :shock: You know how much filtering is done in professional spray booths? (hammer) (hammer) They use positive pressure. filtered air is forced into the booth to stop any outside dust creeping in through the doors and crevices. =D> =D>