Dust collection in a small shop. How to suck?

[studders]

Actually I've been thinking again (twice in one day, gotta be a new personal best). The filtering needn't be at the Cooker Hood, it could be in the ducting. By jove Watson, you may be on to something. :shock:

 

[GraemeD]

For lowest resistance to airflow, the filter has to be as large a surface area as possible. Think about it this way....to trap super tiny particles, the filter has to be quite dense......but if you pass the air through a large area of it, then the resistance to flow is better.

I'd suggest you find some suitable filter material first and see if a duct sized piece works. Otherwise, you'd have to widen it up somehow....either by making the duct outlet larger, or put it pre-fan on the inlet grid.

From my research, the filters are usually like the ones in the link you found (ie. a simple pre-filter, and then a bag style high grade filter (bag style increases that surface area to improve flow!). Could buy spares from Axminster or similar for one of their machines. Not cheap however.

Microclene use a different approach, essentially a wad of fibres which they claim traps submicron dust. My research suggested that this is hard to believe.....and I even went as far as speaking with some filter suppliers to see what they thought (and they were equally skeptical!). However, it makes for a much simpler and cheaper filter.....you can buy this kind of material for a few quid a metre online.

But does it protect you??!

Cheers
graeme

 

[studders]

Hmmm. A bit more to it than I first thought. Thanks for the info and ideas though, I shall work on it. (where's the Mad Inventor smiley when I need one?)

 

[Digit]

One reason I suggested the Henry is that from my own experience of commercial units they tend to be rather ineffective in my long narrow shop, I see a vac type as portable, or several at strategic points and connect the said vac to the nearest when working.

Roy.

 

[GraemeD]

I must admit I came to the same conclusion! It's not hard to make something that seems to collect dust from the air.....and you could argue that any less dust is a good thing. For convenience, even some basic filtering would probably reduce the amount of fine dust settling on everything in the shop, so you could argue it's worth doing. BUT....the harmful dust is submicron, and therefore so small it's invisible to the eye. Simple filters won't catch this, hence the commercial units have lots of airflow and very dense filtration.

I guess what I'm saying is that you can make a simple filter, but that doesn't mean you don't need a good dust mask or respirator. See it as a way to make your environment cleaner, but is only part of the whole plan!

 

[wizer]

I take it the best thing to do would be to use the spare filters that Axi sell for their Jet\MTM units?

 

[GraemeD]

I think that's the easiest....though they aren't exactly inexpensive! There are industrial filter suppliers you can buy from online who seem a lot less expensive, but then you're on your own as to what kind to get. The suppliers can advise, but won't guarantee that it will do what you need of it. A minefield! That's why I bought a used Microclene in the end, as it was taking up too much brain bandwidth!!

 

[wizer]

I think there has been some very useful information in this thread. I've learned that a centrifugal fan would be better and that cooker hoods use centrifugal fans. My only issue with that is any cooker hood I've ever used has been terribly noisy and if I am speccing this thing myself I want it to be quiet. Otherwise I won't have it on while I'm working and tend to only use it when the machines are on.

Can someone tell me. Do these work in the same way as air conditioning? In that if you have an external door or window open, they're effectively useless? ie the room can't have a free flow of air?

 

[GraemeD]

I'd say an open window is ok. Think of it this way. The air in the room has dust in it....and outside is dust free (I guess it depends where you live, but you get the idea!). The air cleaner is passing air through its filter, removing particles. It won't get them all in one pass, hence the 6 to 10 passes per hour recommendation. Each pass through removes some percentage of the particles, progressively making the air cleaner. The fact that some dusty air leaves the room.....or new dust free air comes in is nether here nor there, in fact probably an advantage in some ways. Unlike air con, the outside world is not what you want (ie. hot and humid), so you need to keep it out. In this case the outside world is exactly what you want, so let it in!

Worth mentioning that air cleaners are more of an "after the event" solution. If you're still routing or sanding, then the steady reduction in dust that the filter is providing is going to be overwhelmed by the new particles being generated! So, removal at source, is good. A dustmask is good too whilst you're working. The air cleaner is to bring ambient levels of dust down once you've finished making the dust.

As for the noise, that's mainly the air turbulence which is why the Microclene is so noisy too. No way around that....if you want to move lots of air through a small space, it makes a noise. Only way to make it quieter is to move less air, but that defeats the requirement. I agree, cooker hoods are noisy (we never use ours for that reason!), but it seems there's no way around this.

Make sense??

 

[wizer]

yep thanks, helps a lot.

 

[grafter]

it would seem logical to use a hoover with a hepa filter HEPA filters, by definition, remove at least 99.97% of airborne particles 0.3 micrometers - this must be enough?

are their any henry type cleaners with a hepa filter (bit more industrial than argos's finest)?

this would then save hassle and any hoover with washable hepa filter could be used with mikes magic box/niki's various great designs

or is there a better way to incorporate this into the design without reducing the air flow?? anyone have any ideas?

 

[GraemeD]

Such a plan is fine for extraction, but no good for ambient air cleaning (if that's what you meant). The airflow is not sufficient for anything but a very small shop, and the noise would be obtrusive.....remember these cleaners need to be left on all day plus a couple of hours after work to be effective. then there's the electricity bill......a henry is 1kW after all!

 

[grafter]

i was thinking for machine use rather than air cleaning - trying to catch as much as possible with a HEPA filter at machine end would seem a good idea?

however i see the need for two systems really and after building something for machine use, i suppose an ambient air cleaner will follow- i imagine something like Dave L design:

https://www.ukworkshop.co.uk/forums/view ... lter#58301

 

[GraemeD]

Fair enough! The HEPA filter is fine, but gets clogged quite quickly, hence the move towards cyclones for dust separation. The simpler dust separators which just let the heavier dust drop out do help make hoover emptying less frequent, but leave the fine dust in the air to be caught by the HEPA. Like Dyson say, the suction then gets reduced over time and the effectiveness drops off.

I actually tried an old Dyson cyclone unit as a pre-filter in my shop system until recently. A bit of deft butchery gave me a workable system. It also seemed very effective at separating out even the finest dust. However...it also reduced the suction available at my machines, as it restricts airflow. If it were bigger and less restrictive (like a proper shop cyclone) it would be great, but the domestic sized cyclone wasn't unfortunately up to the job. I thought I had a great solution, but once again back to the drawing board!

 

[Boz62]

are their any henry type cleaners with a hepa filter?

Yes, Henry has a "Microtex" option that can be retrofitted or bought as new with a Henry and others by Numatic.

Microclene say their MC100 is to EU4 spec. Not especially hard to meet. EU7 is the normal HEPA type level I believe. So I've wandered if for a smaller workshop filter it might be OK to use a car interior pollen filter, which are easily obtainable for retrofit in Halfords etc. Just an idea...

Boz

 

[BigShot]

I'm really quite proud of this thread now!

So really it comes down to this (in DIY terms)...

For dust extraction at the machine:
Build a box like Mike Garnham's (or a cyclone) with a Henry type vac attached and HEPA filters to catch any dust that makes it through the box (/cyclone) and vac bag.

For ambient air filtration
Something along the lines of DaveL's filter - either with a more powerful axial fan or a centrifugal fan like found in a cooker hood.

I have the feeling that even a very effective solution for these two issues won't remove the need for a personal filter too (from something as simple as a face mask up to the "air cap" type); because no matter how good your machine extraction and ambient filters are, there's still going to be sub-micron dust floating around and that needs to be avoided - particularly when using things like power sanders or sanding on a lathe.


On the filtration front, I think it probably is best to get spare filters as DaveL did, and while it's not a very cheap approach, I think it probably comes close to the ideal balance between saving money on the machine itself while getting good quality consumables which protect your health and work environment.
There's always the possibility of getting filter material of the correct kind and making your own filters from them (better they are glued than sown, considering the particle size I imagine the needle holes could be an issue in a stitched solution) but I do feel that might be edging into false economy unless making it when truly at a loose end.

 

[grafter]

+1 thanks for advice all

 

[GraemeD]

I think that's a pretty succinct summary of the way I see it....after a lot of surfing and reading earlier in the year!

Now.....just make sure you guys post any pics of what you make, so we can all keep track of progress!!

 

[Digit]

Worth mentioning that air cleaners are more of an "after the event" solution. If you're still routing or sanding, then the steady reduction in dust that the filter is providing is going to be overwhelmed by the new particles being generated! So, removal at source, is good. A dustmask is good too whilst you're working. The air cleaner is to bring ambient levels of dust down once you've finished making the dust.

Which is why I gave mine away to a poster on here and extract as much as pos at source and use an air mask.
The down side is that the shop needs a regular bout of dust removal. Can't win 'em all!

Roy.

 

[wizer]

Graeme would any of the filters on this page...

http://www.rbindustrial.co.uk/Panel%20Filters.htm

...be suitable for an air cleaner? This site has just been mentioned on another thread.