Author Topic: Custom Air Purifiers  (Read 3818 times)

williamfaulkner

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Custom Air Purifiers
« on: January 07, 2014, 10:55:15 AM »
Hi Everyone,

First post! First, if I may, a quick question and then some background info for your consideration. I attached a picture showing what I'm trying to build.

In a box (35cm x 35cm x 20cm) that's connected to a centrifugal fan (white noise), and using dense, cushy, black foam (KTV style 3cm thick stuff they put in the walls), what is a good noise reduction design?

I'm thinking of doing a muffler type thing, stacking four sheets of foam with space between each, and alternating hole in the middle on the first sheet, then the opposite (solid middle, air flowing on the sides) on the next and so on, as to reduce the overall noise. I also thought maybe just a lot of holes, randomly sized and positioned. I hope to get some advice on this.

I'm a Canadian living in China with my family, and I've built myself my own air purifier system. Now it appears I can start making a living out of the things. My neighbors and friends trust us and want to pay me to make them a few. A straight forward affair, a simple box with a prefilter at the bottom, a centrifugal fan in the middle and a HEPA H14 filter on top. All of that is wrapped in plywood using screws and airtight from good old tape. They are my first two, so they're primitive but I intend to make them visually pleasant later. Right now the goal is to make these things quieter, something that the industry has singularly failed to do, and something that is somewhat of an Imperative with my wife ;D, and potential customers. I appreciate your help.




Randy S

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Re: Custom Air Purifiers
« Reply #1 on: January 08, 2014, 06:40:50 PM »
just create a baffle box and make sure you do your cfm calculations correctly and that should work.

google "baffle box" you can see images of lined boxes with series of turns that reduce sound.
Randy Sieg

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888-942-7723
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williamfaulkner

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Re: Custom Air Purifiers
« Reply #2 on: January 09, 2014, 01:59:47 AM »
Randy,

Thanks for the answers. I can do a baffle box.
I'll post you a picture :)

I have a lot to learn about soundproofing science in general, the math, the materials, there's a lot to learn.
Any links for that would also be much appreciated.

Thanks again,

William


Randy S

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Re: Custom Air Purifiers
« Reply #3 on: January 09, 2014, 04:56:38 PM »
I am not an expert at air flow calculations but I can tell you that for every 90* turn equals 5' of straight pipe.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

williamfaulkner

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Re: Custom Air Purifiers
« Reply #4 on: January 15, 2014, 12:16:40 PM »
Hi Randy,

It turns out that adding a baffle box at the bottom and top only reduces noise by 5 to 7 db, according to the meter. Weirdly, though, it remains a valuable improvement since the baffles take care of the annoying high frequencies. The bottom baffle prove useless in dba and in over perception. Just one at the top is sufficient. It appears, with a baffle box, to be substantially quieter.

A note to anyone trying out this: you'll need to ensure that your dense black ktv style foam is wrapped in tape. Leaving it as is proved to be a source of particulate matter, going against therefore the idea of an air purifier. I went from 0 at 0.5 microns and 2.5 microns to 2300.

Thank you for your help Randy, its much appreciated.

Randy S

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Re: Custom Air Purifiers
« Reply #5 on: January 15, 2014, 03:56:04 PM »
William.

Actually thats a pretty good noise reduction for your first go at it! 5-7db is a minimum 40%-50% reduction.
Now that the concept is there, using better material will improve the reduction and eliminate particulates.

Use a closed cell foam like these.
http://www.supersoundproofingsales.com/Foam-Mat/products/17/
to line the box and use as the 90* turns.

and the second part is making the box more dense / heavier with products like mass loaded vinyl or cement board...
http://www.supersoundproofingsales.com/Mass-Loaded-Vinyl-MLV/products/28/


Glad to be of help.

Randy S.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

 

anything