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Filtration revisited

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Lonsdale73

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Still can't get a hold of a 480mm filter to fit my dust extractor although 320mm seem readily available. In another thread, a member said he created a 'donut' to allow (I assumed) a larger filter to fit his extractor so I'm wondering what would be the implications of creating a "step-down donut"?
 

grumpycorn

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I created the donut! Yes, it was to step down from a bigger filter diameter to a smaller extractor lip. I take it you're looking to create an 'upside down top hat' affair? (Apologies, it's the best I could come up with).

My extremely uneducated guess is that it would restrict the surface area that the air can flow through by about 45%. Would that throttle the overall system? The common advice is to always avoid stepping down extraction pipe etc. wherever possible so I'd assume it would reduce overall draft fairly severely.

You could make a donut out of ply or something that has an inner radius cut-out of 320mm to restrict the area under your current bag/filter and see what the effect is?

That all sounds very simplistic... hopefully someone with some science will step in!
 

Inspector

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Have you tried contacting one of the filter suppliers to industry that make replacements for the brand names? They might be able to make larger diameter filters for you or at least tell you if the smaller diameter ones would be an issue.



Pete
 

Lonsdale73

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Have you tried contacting one of the filter suppliers to industry that make replacements for the brand names? They might be able to make larger diameter filters for you or at least tell you if the smaller diameter ones would be an issue.



Pete
Yes, spoke to DJN when you mentioned them before and they said they would likely be prohibitively expensive for something that wasn't quite the same and I looked at the other one who offer diameters of 320 and 500, the latter being quite a bit more expensive than even the Axi one, not that either was in stock.
 

Lonsdale73

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My extremely uneducated guess is that it would restrict the surface area that the air can flow through by about 45%. Would that throttle the overall system? The common advice is to always avoid stepping down extraction pipe etc. wherever possible so I'd assume it would reduce overall draft fairly severely.
So sorry, I didn't spot your reply but yes, I was thinking that could be a problem, envisioning the filter being launched like a cork from a champagne bottle. Where did you get your filter from? I think you said it cost around £160-something?
 

DBT85

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Still can't get a hold of a 480mm filter to fit my dust extractor although 320mm seem readily available. In another thread, a member said he created a 'donut' to allow (I assumed) a larger filter to fit his extractor so I'm wondering what would be the implications of creating a "step-down donut"?
I know exactlywhere you can get the size cartridge filter you want. Just give me an hour to pit the kid to bed.

Edit:

Is see you have already spoken to DJN. They sorted me out a CS495 (487mm internal diameter for the cuff) 600mm tall for £155 posted. Could have had it any size I wanted and eventually I may up it but right now its fine.

That's a larger yet cheaper filter than the one Axminster sell with the nice paddles to ruin your filter media. It also has actual spec sheets so you can see just what it is doing.

The CS478 is what you'd need for a 480mm diameter fitting.
 
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grumpycorn

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Where did you get your filter from?

the one Axminster sell with the nice paddles to ruin your filter media
I got the Axminster one!! It seems pretty decent but I’ll fully admit to not doing much homework on alternatives. It reduced the amount of dust in the workshop considerably compared to the old bag filter. I didn’t notice any drop off any performance having used the step up donut
 

DBT85

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I got the Axminster one!! It seems pretty decent but I’ll fully admit to not doing much homework on alternatives. It reduced the amount of dust in the workshop considerably compared to the old bag filter. I didn’t notice any drop off any performance having used the step up donut
Oh the filter itself is fine I'm sure. It just bugs me that a supposed to be a safety thing never seems to have any actual data sheets to prove it, or proper diagrams with internal diameters, etc.
Do you have a link to it. I can't see it on their site or even a search facility.
It was all done via email with a chap called Dan. He was very helpful. This is the chart of filter sizes with dimensions



The only downside was that I originally enquired about a 1m tall one and they thought the best option would be to send it on a pallet due to its size at a charge of about £55!

This is where they actually come from

and this is the page for the various filter media you can have

As suggested by Dan I had the 909ALU filter media. They can provide the spec sheets for them if you ask.

The collar is a soft yet firm PU that will flex enough to get it over a lip of something. I've not clamped mine down yet but I shall. No idea if mine is sized right for my 3hp extractor as it might need to be bigger really, but that's a bunch of testing for another distant day. It works.

Mine worked out to 7.8m2 of filter material.
 

MikeK

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This is where they actually come from

and this is the page for the various filter media you can have

As suggested by Dan I had the 909ALU filter media. They can provide the spec sheets for them if you ask.
Thank you for this information! I exchanged emails with Dan a while ago when I was trying to source a replacement for my Wynn Environmental MERV 15 filters when the time comes. Dan didn't couldn't recommend anything, but after seeing what is available on the Nordic Air website, as well as the filter material specifications in this PDF from Guardfilter, I think I will contact Nordic Air directly.

Based on the information in the PDF, the 909ALU is rated at MERV 10 (1 to 3 micron). The UX NANO and UX NANO FH are rated at MERV 15 (0.3 to 1 micron), and I think this is the same material Wynn Engineering used for the filters I have.
 

DBT85

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Glad to be of some use (y) Check with them, for reasons unknown they don't include a little tick next to wood dust for those UXNANO filters.

Do let me know what they say, they seemed more than happy to help me when I questioned one of their spec sheets. This wil do me for now as its really only used on the TS at the moment, and that's been out of action for 10 weeks!
 

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