Air filters

[matt]

Hmmm... having given this more thought and glanced briefly at Bill Pentz's pages on the subject (credit to "ondablade") I'm thinking I should just extract the ambient dust to the outside which, in my book, equates to "filtering" the workshop to 0 microns! I have a space down the side of my garage which is largely damp etc so would make an ideal space to vent to.

I was thinking of one of these to power it.

 

[RogerS]

To be honest, Matt, I reckon that's too feeble a fan to do much good. Also what will you do in winter? Suck your hot air outside ? :wink:

 

[matt]

To be honest, Matt, I reckon that's too feeble a fan to do much good. Also what will you do in winter? Suck your hot air outside ? :wink:

What hot air?! You have hot air in your workshop in the winter? I rarely bother heating the garage in the winter, especially if I'm machining stuff. By contrast, in the summer, I'd be very grateful for sucking as much hot air out as possible.

I realise that particular fan is not strong enough but something similar but more powerful could be the answer.

 

[DaveL]

I realise that particular fan is not strong enough but something similar but more powerful could be the answer.

The problem I see with that type of fan, if not used with a cyclone to dump the dust, is damage to it as 'stuff' tries to go through it. :x
It is quite surprising what I retrieve from the dustbin under my cyclone, particularly if the grandchildren have helped to clear up. 8)

 

[matt]

I was planning to use the fan/extractor instead of an air filter (i.e. pulling air up near the ceiling to outside the shop). I'd have be very unlucky to get a large lump pulled into it but could put a grille across the outlet.

Reading Bill Pentz's pages is enough to make one want to sell all machinery and revert to using just handtools!

 

[RogerS]

.....
Reading Bill Pentz's pages is enough to make one want to sell all machinery and revert to using just handtools!

You'll not be wanting to read these pages then

 

[matt]

Just watching Norm machining wood. Good to see him putting onhis ear defenders...

 

[Recky33]

How big is your workshop Matt

 

[matt]

How big is your workshop Matt

It's just a single garage

 

[Recky33]

Bout 6*3*3 mtrs then ?

 

[matt]

5m x 2.5m x 2.8m...

 

[Recky33]

If you’re just going to dump it outside get one of these, cheaper as well.

http://www.progrow.co.uk/acatalog/info_315.html

Completely clear your room every 4 minutes

Just put it in an MDF box with rockwool packed round it to reduce the noise, not that they are really noisy, it will self cool itself as long as it’s running
If you find it’s a bit too much I think I have a diagram for a fan controller somewhere so you can turn it down, just run the whole thing off a 15 min timer

HTH

Allan

 

[matt]

I like it! Thanks for the link.

 

[frenchie44]

the Microclenes will filter down below 0.4 micron, but the arrestance rate is lower, as it is with any filter. overall the arrestance rate is 90% 0.8 to 8 microns, larger than 8 microns the arrestance rate is higher, lower ,below 0.8 microns, but all filters will get better at catching the smaller particles as the filter is used, the more dust in the filter the better it gets, up to a point.
the most dangerous particles are those below 10 microns, the range of dust particle size from woodworking machines is mostly in the 30 micron to 2 micron. the human eye cannot see a 10 micron particle.

 

[matt]

Hi. Welcome.
I'm particularly interested in the point you make about the particle size from woodworking (ie mostly 30 to 2 micron) as this is so relevant to filter performance, although your use of the word "mostly" leaves scope for sub 2 micron dust to exist and therefore remain a potential hazard. Nevertheless, would you mind sharing the source of this statistic?

 

[wizer]

At Ally Pally Microclene was showing off their portable air filter. This seems to make much more sense to me. As if the filter is fixed to the ceiling, then the dust surely has to pass over you to get to the filter. In which case you're breathing it all in anyway. Fair enough you are reducing the amount in the air. But it makes much more sense to have one situated right next to the thing that's creating the dust

 

[matt]

I'm completely off the idea of a filter at the moment. What it doesn't filter it blows in to the air. Hence my current thinking to extract ambient air outside and exhaust my DX5000 outside too.

 

[philb88]

I'm completely off the idea of a filter at the moment. What it doesn't filter it blows in to the air. Hence my current thinking to extract ambient air outside and exhaust my DX5000 outside too.

That sounds like a plan! I was planning to get a decent filter etc, but am now also planning to have the whole extraction unit outside, so exhaust and collection drum. Meaning not only the filter exhaust air doesn't return any dust but also the dust it does collect is outside too.

The only thing I reckon a filter is good for is cleaning the air when the workshop is empty like over night, as walking around unsettles the air and dust on surfaces!

Been reading Bill's pages too, now i want to build new shrouds for all the collection on machines!!

 

[matt]

Despite dismissing the idea of a filter I am considering a powerful extraction fan to pull ambient air outside. I am also toying with the idea of a blower too to create movement in the shop to keep the air circulating so the dust actually passes the outlet rather than linger in corners where there is little or no movement. The latter thoughts are triggered by the realisation that suction (even with a massive fan/motor) is simply not powerful enough to create anything more than a channel of movement, thus leaving dead spots. Meanwhile, a relatively small, well positioned, fan can exert quite a lot of movement. Think about trying to suck up some dust offyour bench versus blowing it...

 

[Eric The Viking]

Think about trying to suck up some dust offyour bench versus blowing it...

I used to work in a factory that made computer hard disks. The company concerned pioneered the 'clean tunnel' approach, as opposed to a clean room.

The assembly was done on conveyors moving slowly past workstations. Parallel to the conveyor, above it were air inlets, from which came very filtered clean air. Right in front of the operators, down to elbow height, were perspex shields, directing the air down, out and away off the edge of the bench and over their knees. They did have to gown up, but only from the waist upwards, and they didn't need face-masks. It was much more comfortable and civilized for the assembly line people than working in a clean room, and the company claimed both cleaner air, and fewer failures too (I believe them). I think it's now become the standard approach (for non-automated processes).

So, to apply that to woodworking, sort of: The particles they had to filter and eliminate were the same size as (or smaller than) the worst woodworking dust. Whilst their filtration cost $loads, the principle of using gravity to advantage still applies: I'd be inclined to introduce fresh air above, and extract from lower down. At worst you hinder dust rising to mouth level, at best it might be a lot more effective than the ceiling mounted filters I've seen in catalogues.

How? In a new build, I'd run a 'ring main' of duct round the wall at ankle level (and bench level where appropriate). I realise this is impractical in an existing shop, but you might drop small ducts down the wall to inlets at the right height.

For incoming air, you could just take it from outside. To avoid unwanted draughts, you might adopt the approach used in Victorian chapels: a vertical duct, with the inlet lower down on the outer wall, stops colder air "falling through" the high level opening into the building - ventilation without discomfort. These vents aren't usually very tall - about six feet difference in the ones I've seen. I'd want something like this:

I'd also arrange any baffling so that there was more suck from the lower vent, to encourage the downdraft further.

Your mileage, etc...

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