Air filters

[matt]

OK, I'm now seriously considering air filters. One of the main selling points seems to be turnover - ensuring there is enough capacity for the space to be filtered. However, particle performance is another stat that I've been looking at too. The Jet and Axminster machines seem to only filter down to 1 micron. This seems a bit of a nonsense to me given that we strive to ensure vacuums filter down to 0.5 micron. What's the point in having a machine that actively circulates particles <1 micron around the workshop?

(The Microclene MC400 seems to filter 95% below 1 micron and 65% down to 0.4 micron so appears an obvious choice. However this does not seem to be an especially popular choice in these parts which makes me curious...)

What am I missing?

 

[woodbloke]

I use the Axminster ambient air filter...no problems thus far - Rob

 

[Boz62]

I suspect there is a lot of "specmanship" with these filters. I would rather they give a true spec, like the Microclene ones, then at least we could compare like with like. They will all have a cutoff slope, with a degree of filtering at smaller sizes than the supposed sharp cutoff that most filters show.

From digging round for specs, I believe that Microclene spec is equivalent to an EU4 spec. You can get up to EU7 (smaller particle size filtered as the number goers up), so there is room to improve commercial filters. I had wondered about making a DIY one based on a replacement interior pollen filter from a car - they are fairly cheap, easy to get, and seem to be around EU4 or better depending on who you believe.

Boz

 

[matt]

I use the Axminster ambient air filter...no problems thus far - Rob

Therein kinda lies my dilemma... How would you know? Most people are delighting in the performance of their filters based primarily on visible dust which is larger than (I think) 5 microns - anything less we cannot see. So we are wholly reliant on the specs to understand the benefit (until such time as the side-effects of dust on health begin to surface or not).

 

[Mike.C]

I use the Axminster ambient air filter...no problems thus far - Rob

Therein kinda lies my dilemma... How would you know? Most people are delighting in the performance of their filters based primarily on visible dust which is larger than (I think) 5 microns - anything less we cannot see. So we are wholly reliant on the specs to understand the benefit (until such time as the side-effects of dust on health begin to surface or not).

Matt thanks for the info, which certainly makes you think I have the Axminster/Jet AFS 2000, and the outer filter catches so much dust it gives me a sense of security. Although now that you have told us it is the unseen dust that does the damage, it now seems that it is a false one :roll: Lets just hope the inner filter catches them.

Cheers

Mike

 

[woodbloke]

I use the Axminster ambient air filter...no problems thus far - Rob

Therein kinda lies my dilemma... How would you know? Most people are delighting in the performance of their filters based primarily on visible dust which is larger than (I think) 5 microns - anything less we cannot see. So we are wholly reliant on the specs to understand the benefit (until such time as the side-effects of dust on health begin to surface or not).

I've been working with wood and the associated hazards since the early 70's when I didn't (and nor did anyone else for that matter) take much notice of the hazards of wood dust and as I said, thus far, so good.
Whilst I do now appreciate the dangers and do all that I can reasonably (and that's the caveat) reduce it in my 'shop to reduce the risk...wood dust is part of the territory . That said it's impossible to eradicate it altogether, much as I'd like to, so I'm happy to live with the small risk that I have at present in my 'shop.
That said, the dust/airborne hazards that we encounter in daily life may be equally as hazardous...ever followed a bus on a pushbike?..or are you a smoker? - Rob

 

[Mr Ed]

I have the small Jet filter - it seems to do its job, although as said earlier in the thread, I have no real way of knowing how successful it is.

My view however, is that even though I cannot define how well it works and what particle size it captures, it must be better than not doing anything and on that basis I continue...

Ed

 

[Mike.C]

I have the small Jet filter - it seems to do its job, although as said earlier in the thread, I have no real way of knowing how successful it is.

My view however, is that even though I cannot define how well it works and what particle size it captures, it must be better than not doing anything and on that basis I continue...

Ed

Until someone comes up with a way of letting us know how small a particle the filter is picking up, that is all we can do, and as you say it has got to be better then not having one.

Cheers

Mike

 

[matt]

The filter manufacturers do include the stats in their specs. That was what surprised me initially and made me think I was missing the point. Many don't filter below 1 micron :shock:

I agree that some filtering is better than nothing but surprised this has not come up before given the astuteness of this forum when it comes to purchases (another reason I thought I might be missing something).

 

[woodsworth]

I use the Axminster ambient air filter...no problems thus far - Rob

Therein kinda lies my dilemma... How would you know? Most people are delighting in the performance of their filters based primarily on visible dust which is larger than (I think) 5 microns - anything less we cannot see. So we are wholly reliant on the specs to understand the benefit (until such time as the side-effects of dust on health begin to surface or not).

I've thought the same thing ever since reading Bill something or others site on dust removal and cyclones.

I think a good well designed cyclone and a good filter is the only real defense against the unseen nastiest. But as others have said, woodworking has hazards and i don't think you can be one hundred percent dust free. I think of the things i was made to do as an apprentice years ago would be considered unthinkable now, so things are getting better.

The cost of a well designed and functioning dust removal system is prohibitively expensive so I make do with what i can afford now and as i can afford better i will do better. The Filter you are looking at sounds great, how do you know when it is full? If you can't see the dust, is there just an hourly operating time to replace it? What about electrostatic filters? Those are washable aren't they?

 

[Harbo]

I use an Axminster over my TS, BS and Router and a Microclene over my lathe and Woodrat.

In the past members have complained that the Microclene is nosier but when checked with a sound measuring gauge it has a lower dB level but emits at a higher frequency level which makes it appear louder.

Rod

 

[matt]

With regard to knowing when the the filter is full... I skim read about using a piece of A4 paper in the Microclene instructions. When the filter is new you place the piece of paper on the outside and time how long it takes to fall off. When it takes half the original time to fall off it is time to replace the filter. Something along those lines in any case. Not particularly scientific but better than nothing at all.

 

[woodsworth]

So from what i can gather from your reply then this is for filtering the air and not the exhaust of your dust collection system? It would be hard to get the paper to stick if it was used as an exhaust filter.

In that case where are you going to put it? One at each machine? If not i don't see the point. How much of it will you breath in before it gets to the filter? I could see putting one over a lathe as you do a lot of sanding, otherwise i'd put my money into catching it at the source.

 

[matt]

It is to filter the air in the workshop rather than the extraction exhaust (which is already filtered down to 0.5 micron). You have sufficient filters for the space (one in my case) and position them where recommended by the manufacturer. I will continue using a mask when actually machining and for probably the remainder of a session in the workshop. However, airborne particles can (apparantly) remain in the air or susceptible to easy disturbance for some time. The idea behind the filter is to trap as much as possible so I can be in the workshop at other times without concern about the invisible dust floating in the air or on surfaces. It sounds paranoid but I don't want to regret not taking reasonable steps to mitigate potential side-effects.

 

[woodsworth]

I don't see it as paranoia at all, it just seems to me that if it is already floating around before it gets to the filter how much of it are you going to breath in before it gets there? It's like playing roulette. But i guess if you've already covered the removal up to .5 microns then your mostly catching what didn't go through the system in the first place.

 

[Eric The Viking]

I use an Axminster over my TS, BS and Router and a Microclene over my lathe and Woodrat.

In the past members have complained that the Microclene is nosier but when checked with a sound measuring gauge it has a lower dB level but emits at a higher frequency level which makes it appear louder.

If it's annoying you then you may be able to baffle it successfully with Rockwool. The higher the frequency, the easier it is to absorb acoustically, and you'd probably only need a piece of 10mm ply with 2" Rockwool stuck to it hung up a few inches from the noisiest bit (which I assume is the outlet). It doesn't need to impede the airflow, just be at right angles to it, so the air is forced to move past it.

That said, it would have to be a pretty loud filter to drown out the router in the Wood Rat!

 

[Richard Findley]

Hi Matt,

I have the Jet medium sized filter and the difference it makes is HUGE her's a picture of it after running for just 2 hours:

Even on the low setting you can feel the air moving around the workshop, and it is filtered air too!!!

I take your point about the level of filtering, would using the charcoal filter improve it any do you think??

Cheers

Richard

 

[matt]

LOL, Richard - that filter is normally blue, isn't it?

I'm not sure whether the charcoal filter would make a difference. I'm no expert but I imagine the manufacturer's have to balance filtering against the effect on flow/turnover and then, if they decide to use more powerful motors to maintain flow AND improve filtering they then need to factor in noise and total cost too. So, if my assumptions are correct, I imagine the charcoal filter would not make a difference because the finer filtering needed to stop smaller particles would impact flow.

I'm currently looking at the *NEW* Microclene MC760. More turnover than I actually "need" but, in the grand scheme of things, it's not a lot extra to pay over the MC400. I also want to use it in the house when decorating so the MC760's flexibility when it comes to positioning is good too as I can simply stand it somewhere rather than have to try and hang it near the centre of the room etc...

 

[RogerS]

So from what i can gather from your reply then this is for filtering the air and not the exhaust of your dust collection system? It would be hard to get the paper to stick if it was used as an exhaust filter.

In that case where are you going to put it? One at each machine? If not i don't see the point. How much of it will you breath in before it gets to the filter? I could see putting one over a lathe as you do a lot of sanding, otherwise i'd put my money into catching it at the source.

The proof is in the eating. After running my homebuilt jobbie for a couple of hours you can see the outer face of the filter go brown. As well as my extractor, I run the air filter while in the shop. Anything to get the dust out of the air.

 

[woodsworth]

The proof is in the eating. After running my homebuilt jobbie for a couple of hours you can see the outer face of the filter go brown. As well as my extractor, I run the air filter while in the shop. Anything to get the dust out of the air.

Point taken. Better in the filter then in the air.