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johnny_poke
Brownian movement
Registered: 12/03/08
Posts: 442
Loc: Europe
Last seen: 10 years, 6 months
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DIY HEPA filter?
#9748371 - 02/06/09 08:15 AM (15 years, 1 month ago) |
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Has anyone ever had any success building their own from the ground up, filter, air pump and all?
From the description of a HEPA it would seem that someone with good DIY skills could do the lot, even build the filters.
Excerpt from Wikipedia:
Quote:
HEPA filters can remove at least 99.97% of airborne particles 0.3 micrometers (µm) in diameter. Particles of this size are the most difficult to filter and are thus considered the most penetrating particle size (MPPS). Particles that are larger or smaller are filtered with even higher efficiency.
HEPA filters are composed of a mat of randomly arranged fibres. Key metrics affecting function are fibre density and diameter, and filter thickness. The air space between HEPA filter fibres is much greater than 0.3 μm. The common assumption that a HEPA filter acts like a sieve where particles smaller than the largest opening can pass through is incorrect. Just as for membrane filters, particles so large that they are as wide as the largest opening or distance between fibres cannot pass in between them at all. But HEPA filters are designed to target much smaller pollutants and particles are mainly trapped (they stick to a fibre) by one of the following three mechanisms:
1. Interception, where particles following a line of flow in the air stream come within one radius of a fibre and adhere to it. 2. Impaction, where larger particles are unable to avoid fibres by following the curving contours of the air stream and are forced to embed in one of them directly; this effect increases with diminishing fibre separation and higher air flow velocity. 3. Diffusion, an enhancing mechanism is a result of the collision with gas molecules by the smallest particles, especially those below 0.1 µm in diameter, which are thereby impeded and delayed in their path through the filter; this behaviour is similar to Brownian motion and raises the probability that a particle will be stopped by either of the two mechanisms above; it becomes dominant at lower air flow velocities.
Diffusion predominates below the 0.1 μm diameter particle size. Impaction and interception predominate above 0.4 μm. In between, near the 0.3 μm MPPS, diffusion and interception predominate.
The initial filter air flow resistance and final filter air flow resistance are typically measured as pressure drop across the filters.
Polyester fibre fill would do the job if arranged correctly no?
-------------------- [quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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RogerRabbit
Bans for Pleasure
Registered: 03/26/03
Posts: 42,214
Loc: Seattle
Last seen: 1 year, 29 days
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Do a quick search. There's been at least fifty projects posted in the last year where members have built their own flowhoods. RR
-------------------- Download Let's Grow Mushrooms semper in excretia sumus solim profundum variat "I've never had a failed experiment. I've only discovered 10,000 methods which do not work." Thomas Edison
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johnny_poke
Brownian movement
Registered: 12/03/08
Posts: 442
Loc: Europe
Last seen: 10 years, 6 months
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Huh! I searched for DIY HEPA earlier and got few useful results. I must have done something wrong. Thanks RR. I will try again
-------------------- [quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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old mushmellow
mushmaker
Registered: 03/15/08
Posts: 549
Loc: the dome
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I bought a hepa air purifier from a department store and incorporated it into a self made flowhood. It saved me allot of work and time and probably money too.
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johnny_poke
Brownian movement
Registered: 12/03/08
Posts: 442
Loc: Europe
Last seen: 10 years, 6 months
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I wish I could just walk into a dept. store and find a HEPA for cheap. I'm not sure what sort of places I'd have to look to find one in my area. What applications might a HEPA be used for?
-------------------- [quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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Cascadian
Feel like a Stranger
Registered: 09/13/08
Posts: 1,130
Loc: Cascadia
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Before anyone makes any costly decisions, i just figured I'd link to this topic that seems to get brought up about once a week.
http://www.shroomery.org/forums/showflat.php?Cat=&Board=2&Number=9540551&fpart=&PHPSESSID=
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johnny_poke
Brownian movement
Registered: 12/03/08
Posts: 442
Loc: Europe
Last seen: 10 years, 6 months
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Re: DIY HEPA filter? [Re: Cascadian]
#9749449 - 02/06/09 12:27 PM (15 years, 1 month ago) |
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Quote:
Before anyone makes any costly decisions, i just figured I'd link to this topic that seems to get brought up about once a week.
http://www.shroomery.org/forums/showflat.php?Cat=&Board=2&Number=9540551&fpart=&PHPSESSID=
Thank you Cascadian, that was a good read. I hadn't even thought far enough ahead to consider the laminar flow aspect of the thing. I was just trying to think of a way to create clean positive air pressure inside a glovebox. Perhaps I will focus on making the existing glovebox a bit less cumbersome instead of worrying about air filtration and positive pressure.
Thanks again all.
-------------------- [quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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RogerRabbit
Bans for Pleasure
Registered: 03/26/03
Posts: 42,214
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Quote:
Perhaps I will focus on making the existing glovebox a bit less cumbersome instead of worrying about air filtration and positive pressure.
Gloveboxes work best with still air, not moving, whirling and turbulent positive pressure air, even when filtered. RR
-------------------- Download Let's Grow Mushrooms semper in excretia sumus solim profundum variat "I've never had a failed experiment. I've only discovered 10,000 methods which do not work." Thomas Edison
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johnny_poke
Brownian movement
Registered: 12/03/08
Posts: 442
Loc: Europe
Last seen: 10 years, 6 months
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Anyway, what I was really talking about was building the actual HEPA filter (not a flowhood). The HEPA basically forces air through 'a mat of randomly arranged fibers' in order that particles in the air get trapped in the fibers. I'm thinking polyfill is likely an excellent candidate. This of course would only work correctly if the air was pumped at the correct speed and the filter material created the necessary resistance to impede and diffuse the air flow sufficiently but these parameters would be easy enough to regulate and experiment with.
What say you? Sounds like a project to me.
-------------------- [quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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johnny_poke
Brownian movement
Registered: 12/03/08
Posts: 442
Loc: Europe
Last seen: 10 years, 6 months
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This may well have been referenced before. Sorry for posting an outside link but I feel it is relevant: Click
Would that work?
-------------------- [quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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Brainiac
Rogue Scientist
Registered: 04/29/06
Posts: 13,259
Loc: 與您的女朋
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No, just go and buy one...They will last five+ years....
-------------------- Fair is Fair
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johnny_poke
Brownian movement
Registered: 12/03/08
Posts: 442
Loc: Europe
Last seen: 10 years, 6 months
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Re: DIY HEPA filter? [Re: Brainiac]
#9750343 - 02/06/09 03:25 PM (15 years, 1 month ago) |
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Aah. OK.
-------------------- [quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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ohmatic
searcher
Registered: 02/28/04
Posts: 6,742
Loc: europe
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Re: DIY HEPA filter? [Re: Brainiac]
#9750353 - 02/06/09 03:27 PM (15 years, 1 month ago) |
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-------------------- MONOTUB tek HEATBOMB tek RIP #cultivation! ....can't associate? well FUCK U !
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Brainiac
Rogue Scientist
Registered: 04/29/06
Posts: 13,259
Loc: 與您的女朋
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Re: DIY HEPA filter? [Re: ohmatic]
#9750377 - 02/06/09 03:30 PM (15 years, 1 month ago) |
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I thank (hope) he was talking about the hepa part...
-------------------- Fair is Fair
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johnny_poke
Brownian movement
Registered: 12/03/08
Posts: 442
Loc: Europe
Last seen: 10 years, 6 months
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Re: DIY HEPA filter? [Re: ohmatic]
#9750688 - 02/06/09 04:20 PM (15 years, 1 month ago) |
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Thank you Ohmatic. That page is book marked and shall be studied. So, the bottom line is if I obtain a HEPA filter with the right amount if resistance and an air pump with the right amount of pressure I would be able to seize the holy grail of laminar flow?
Does anyone know the maths involved to calculate roughly the specs of the items needed? In laymans terms if possible as maths is a weak point.
Ohmatic (or anyone for that matter) exactly what type of fiber is used in HEPA filter units? What exactly is that green material in the pic, do you know?
-------------------- [quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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Shroominit
Part Time Mycologist
Registered: 11/29/08
Posts: 4,662
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Re: DIY HEPA filter? [Re: Brainiac]
#9750714 - 02/06/09 04:22 PM (15 years, 1 month ago) |
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It's made of fiberglass, so no polyfil wouldn't do the job.
Basically they use something like chopped stranded mat,
but it's compressed quite a bit to get rid of the spaces. This has to be done a certain way to ensure that airflow is not completely restricted. The material 'mat' that is created is then folded like an accordian and vertical pieces of metal are added:
The metal pieces help to create an even flow and prevent cross-streaming (that's a technical term, haha) in the inward folds of the filter mat. Every filter that is made is then tested to see how many particles it lets through. I assume they use a set number of easily detectable particles (radioactive?) to do this.
Hope this helps a little. I don't see it being an easy DIY, since quality is the most important part of the finished product. If it's really something you want to try, see if you can't visit a factory and check out how they do it... tell them you're writing a report on air filtration
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veda_sticks
Cultivator
Registered: 07/29/07
Posts: 14,191
Loc: UK
Last seen: 4 years, 2 months
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Dont forget that your filter has to be able to produce laminaro flow, without it no mater how clean the air is coming out, it will be turbulant and pull in and whirle around contaminants.
As RR said theres no reason to filter air in a glovebox. There is also no reason to bleach lysol alcohol clean it either. Still air keeps contaminants settled on the floor and not floating around landing on everything.
I've had great success using a glovebox. I recently made a syringe from a print and it worked perfect.
I'd love a flowhood. If i ever win the lottery im building my own mushroom room, with flowhood and nice glovebox
-------------------- PF TEK - writeup by EvilMushroom666 Lets Grow Mushrooms - RogerRabbit & RoadKills website with sample videos plus the full PF TEK video series. Alot of great information - BUY THE DVD Cakes can and will pin! - So you think cakes suck for pins. Your wrong Franks Simple Coir/Verm Tek Franks Proper Pasturisation Tek Franks Spawning To Bulk - Monotub Professor Pinheads RTV Injection Port Tek Foo Mans No Soak WBS Prep Tek
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johnny_poke
Brownian movement
Registered: 12/03/08
Posts: 442
Loc: Europe
Last seen: 10 years, 6 months
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Aah, my shattered dreams of home made HEPAs
Building the housing will be a piece of cake for me. But alas I cannot replicate the HEPA filter. If I were to drop into an air conditioner supplier/installer and inquire there would I likely get my hands on something usable? Or would those types of filters not be good enough for this work?
-------------------- [quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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Shroominit
Part Time Mycologist
Registered: 11/29/08
Posts: 4,662
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Re: DIY HEPA filter? [Re: Shroominit]
#9750890 - 02/06/09 04:42 PM (15 years, 1 month ago) |
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I have a flow hood. It was not the cheapest thing ever, but IMO totally worth it. You can open a grain jar to transfer agar wedges in with no worries of contams.
Anyhow, the metal strips have uniform bends and are placed at even distances to create laminar flow. Combined with the accordion shape of the filter fibers themselves, it makes the air move where you want it to (evenly, is the point here). The static pressure created by having a deep filter ensures that the flow of air is uniform across the entire filter.
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Mephistophelian
Quasi Hob-Nobbery
Registered: 08/14/08
Posts: 2,527
Loc: Camp Crystal Lake
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I think the message is..if you keep aiming "is it good enough" then it isn't good enough.
There's the types of filters that are absolutely made for that specific purpose..and everything else is just that, everything else. You can get these filters for about $75 if you nail a deal on Ebay...but full price ranges from $140-$170 for a 24x24x6. Which for what it does, is a worthy investment.
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