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budget hepa box


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#1 Hippie3

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Posted 14 June 2006 - 09:13 PM

i hear this works well.

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#2 roc

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Posted 14 June 2006 - 09:20 PM

I thought we went through this years back and found the leakage of the plastic case behind the filter to be excessive... smoke test will tell all.
If it draws smoke into the seams anywhere after the filter then it ain't no good.

#3 Hippie3

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Posted 14 June 2006 - 09:22 PM

workman said he built one using that very model
and it worked well.
i'm inclined to extend him
the benefit of the doubt...
maybe the manufacturer has
improved the design ?
might be time
for a 2nd look...

#4 hogwild

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Posted 14 June 2006 - 09:38 PM

im willing to give it a try. Its time to build a new gb anyways. Might as well build a possi pressure if im going to put the effort into it.

#5 SharkieJones

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Posted 14 June 2006 - 09:44 PM

Interesting concept, might have to try that.

#6 cyberd0c

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Posted 15 June 2006 - 03:11 AM

Hi, I have a similar setup pushing 99.97 filtered air from a trueair purifier thru a merv11 filter. the merv11 is fixed to the back of a modified glovebox similar to the Stamets retrofitted design in TMC. well I thought this would give me something very close to a HEPA flowhood and when I tested it with agar controls all I grew is contam. I tried different exposure times from 30 to 180 seconds. I opened the front pannel of the purifier (pic4)and it had no seal around the filter which did not look to me as a HEPA although it says on the box HEPA technology 99.97. now I use hydrofarm air ionizer with minimal contam until I build my true HEPA flowhood :). I don't know if the purifier above has a true HEPA filter but still there is no seal around it and the exit is bound to collect dust and particles when its turned off.

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#7 cyberd0c

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Posted 21 June 2006 - 08:23 AM

Since my last post I thought about my design and decided to give it another chance, the way I see it two things can be done to eliminate the 0.03 % particles and achieve 99.99% clearance.
One is to replace the HEPA like filter in the purifier with a true HEPA, but the size would be very difficult to obtain if not impossible as it would be custom made specifically for this machine.
two, if I sterilize the air that is going thru the merv11 filter. Behind this filter is a 6" plenum, and so I fitted an 8w UV-C tube in the ceiling as in the picture and will test the air that comes out at the other side of the merv11 by exposing 6 agar plates from 30-180 seconds at 30 sec intervals.

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#8 Lazlo

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Posted 22 June 2006 - 02:06 AM

I use the same type of contraption. I previously thought that the filter had began to let me down but, after inspecting it I found a small hole in it that I had accidentally put in it with a scalpel. I don't even have arm holes in mine anymore. I cut the face clean off my box so I could move more freely and to prevent other mishaps. Nothing a little hot glue can't fix I guess.

#9 waylitjim

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Posted 22 June 2006 - 11:41 AM

Nice setup Cyberd0c :bow:

#10 cyberd0c

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Posted 09 July 2006 - 12:08 PM

I tried the previously described flowhood, which is basically an open glovebox, so I turned the airpurifier on for 10 min after wiping the whole surface with 70% alcohol.

I opened 6 agar plates that have been sitting for three days, in the picture they are numbered from 30 to 180 and one control C.
All were opened at the same time except for the control, then 30 sec later the 30 plate was covered, then the 60....then after two minutes I waited for another minute and covered the 180. The plates were clingwrapped and incubated @ 85F for 48 hours.
So far none have shown any sign of contam. my previous setup grew contam with even brief exposure and the only difference now is the added UV. Could this be the answer?
I intend to keep the plates a little longer to see if any contam will grow.

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#11 cyberd0c

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Posted 12 July 2006 - 12:53 PM

Well, nobody seems to be interested in this experiment but still I will post the last update, It's been 5 days now and no growth detected in any of the agar plates.
conclusion: airpurifier+UV+merv11 flowhood is equivalent to HEPA flowhood

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#12 Hippie3

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Posted 12 July 2006 - 03:22 PM

what kind of UV source ?

#13 cyberd0c

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Posted 12 July 2006 - 03:44 PM

It's an 8w UV-C tube from here http://bulbs.com/pro...ducts&class=902

#14 Lazlo

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Posted 12 July 2006 - 06:27 PM

Have you worked with mushroom spores under that light Cyberdoc?

#15 cyberd0c

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Posted 13 July 2006 - 03:34 AM

no way man, I wouldn't expose my hands to this UV light, neither spores for that matter. the light resides in the 6" plenum behind the merv11 filter which acts as a buffer for the air coming from the purifier allowing it to zap all the particles that escape thru the purifier's filter since it is only 99.97

here's some info about UV-C (germicidal UV)

Germicidal ultraviolet (UVC) light kills cells by damaging their DNA. The light initiates a reaction between two molecules of thymine, one of the bases that make up DNA. UV light at this wavelength (shortwave UV or UVC) causes adjacent thymine molecules on DNA to dimerize.
The longer the exposure to UVC light, the more thymine dimers are formed in the DNA. If cellular processes are disrupted because of DNA damage, the cell cannot carry out its normal functions. If the damage is extensive and widespread, the cell will die.


If the light doesnt kill the cell it will damage its DNA and cause mutations, in the case of human cells it will cause skin cancer. (we're talking about long exposures here, but susceptible skins may not take that long)

#16 Hippie3

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Posted 13 July 2006 - 08:29 AM

yes indeed,
this ain't your blacklight UV
but rather high energy,
harmful to humans and shrooms alike
just for zapping stuff
turn off before working in area




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