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Infiniteshot
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Re: Laminar flow hood filter damage. Hepa me! [Re: gizmo1]
#26779303 - 06/24/20 12:29 PM (3 years, 7 months ago) |
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I’m super paranoid and I feel like a digital “paper trail” gets me closer to trouble than I’d like. PM me and we’ll rap a little. I’ll give you the lowdown.
-------------------- rad
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Infiniteshot
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Re: Laminar flow hood filter damage. Hepa me! [Re: Pastywhyte]
#26779331 - 06/24/20 12:37 PM (3 years, 7 months ago) |
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I’m thinking I’ll run a sleeve of dishes and see what happens. I’ve got a few tubs that should be done in a few weeks and I would think that my dishes would be contaminated by the time I’m ready to try and clone my favorite fruit. Worst case scenario I’m out dishes and agar right?
-------------------- rad
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RoscoeReturns
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Re: Laminar flow hood filter damage. Hepa me! [Re: Sockadin]
#26779405 - 06/24/20 01:20 PM (3 years, 7 months ago) |
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Quote:
Sockadin said: How do you test a Hepa for leaks? I'm interested to try this on mine.
We tested them by introducing DOP aerosol into the blower, and scanning the filter with a photometer. That was leak testing only. It’s not something you can DIY. It takes some specialized and expensive equipment.
When certifying LF or BSC hoods, we also took air velocity measurements with a hot wire anemometer across the face of the filter, particle counts at different places on the work surface, and introduced smoke to visualize airflow. On some hoods we would also use a balometer to measure air volume.
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Infiniteshot
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Re: Laminar flow hood filter damage. Hepa me! [Re: RoscoeReturns]
#26779411 - 06/24/20 01:21 PM (3 years, 7 months ago) |
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I just looked at one piece of the equipment required to get into testing hoods...jeez Louise. That stuffs pricey. I’ll leave testing to the pros
-------------------- rad
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Infiniteshot
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Re: Laminar flow hood filter damage. Hepa me! [Re: Infiniteshot]
#26830690 - 07/18/20 12:27 PM (3 years, 6 months ago) |
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Ok. Update. New filter arrived and box is built. The anemometer I have is totally whack. It’s reading 153 and then only jumps to 28 fpm. So I’m trying the lighter gauge method. How’s this look? Thanks for your time.

Edited by Infiniteshot (07/18/20 12:32 PM)
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The Ole Airstream
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Re: Laminar flow hood filter damage. Hepa me! [Re: Infiniteshot]
#26830707 - 07/18/20 12:40 PM (3 years, 6 months ago) |
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My 24x24 hood blows the lighter out even from 6” away
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southbounpachyderm
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Re: Laminar flow hood filter damage. Hepa me! [Re: Infiniteshot]
#26830717 - 07/18/20 12:50 PM (3 years, 6 months ago) |
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Quote:
Infiniteshot said: Ok. Update. New filter arrived and box is built. The anemometer I have is totally whack. It’s reading 153 and then only jumps to 28 fpm. So I’m trying the lighter gauge method. How’s this look? Thanks for your time.


That doesn't look like you're pushing enough air. Probably gonna need to get a new blower to do effective work in front of that thing.
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Gan
Wielder of Narya



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Flame should be 45-60 degrees approximately 6 inches from the face of the filter
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Infiniteshot
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Quote:
southbounpachyderm said:
Quote:
Infiniteshot said: Ok. Update. New filter arrived and box is built. The anemometer I have is totally whack. It’s reading 153 and then only jumps to 28 fpm. So I’m trying the lighter gauge method. How’s this look? Thanks for your time.


That doesn't look like you're pushing enough air. Probably gonna need to get a new blower to do effective work in front of that thing.
Ok awesome. I had the prefilter tripled up. It’s a cut to fit fabric and I thought the measurement for the 45-60 degrees was at the face of the filter. I removed two of the three layers and here’s the result at 6”. You can see my square down below.
-------------------- rad
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southbounpachyderm
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Re: Laminar flow hood filter damage. Hepa me! [Re: Infiniteshot]
#26830789 - 07/18/20 01:29 PM (3 years, 6 months ago) |
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Thats looking better but I still would suggest you get a higher powered blower. As mentioned by someone above my lighter is non operational within 6in and looks like yours at around a foot from flowhoods face
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Infiniteshot
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Wild. I did all the calced for the blower and the blower is at about 50cfm more than the project calced at.
-------------------- rad
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Gan
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Re: Laminar flow hood filter damage. Hepa me! [Re: Infiniteshot]
#26830853 - 07/18/20 02:05 PM (3 years, 6 months ago) |
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Ideally, the flow shouldn't be so strong that it blows out a lighter 6 inches from the filter. The flame being 45-60 (honestly up to almost 90 degrees isn't a problem most the time) degrees around 6 inches from the filter face is what you want. In a perfect world, you would use an anemometer, but one that is sensitive enough to be accurate at our low flow rates is rather expensive.
OP I cant quite tell the angle of the flame from the angle you took the picture, but if it's following the above criteria, then there's no need for a new blower. Are you using 1 prefilter?
Edited by Gan (07/18/20 02:05 PM)
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southbounpachyderm
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Re: Laminar flow hood filter damage. Hepa me! [Re: Infiniteshot]
#26830892 - 07/18/20 02:23 PM (3 years, 6 months ago) |
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Quote:
Infiniteshot said: Wild. I did all the calced for the blower and the blower is at about 50cfm more than the project calced at.
Are you sure there aren't any leaks around the sides of the filter? could just be your prefilter material. Should be fine tho. I just like to have mine a little overpowered so I can work further from the face '
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Infiniteshot
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Re: Laminar flow hood filter damage. Hepa me! [Re: Gan]
#26830911 - 07/18/20 02:34 PM (3 years, 6 months ago) |
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Yes. I dropped it down to one filter. I was also thinking that I could run it with the prefilter for an hour before I work and then yank the prefilter off In all reality I thinkk it’s fine taking into consideration the bend of the flame and the fact that I’m pretty good at math. My original calcs used the proper formula and filter. I’ll send a better picture of the flame bend when I get home. I’m trying to navigate a world where nobody understands social distancing traffic patterns.
-------------------- rad
Edited by Infiniteshot (07/18/20 03:52 PM)
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inski
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Re: Laminar flow hood filter damage. Hepa me! [Re: Infiniteshot]
#26831059 - 07/18/20 03:55 PM (3 years, 6 months ago) |
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Quote:
Infiniteshot said: Ok. Update. New filter arrived and box is built. The anemometer I have is totally whack. It’s reading 153 and then only jumps to 28 fpm. So I’m trying the lighter gauge method. How’s this look? Thanks for your time.


If this is how your flame looks at that distance over the entire face of your filter it's working very well and producing laminar flow, if you have problems with contamination it will be due to improper sterile technique, if proper techniques are used and there is still contamination the filter is at fault.
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Infiniteshot
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Re: Laminar flow hood filter damage. Hepa me! [Re: inski]
#26831090 - 07/18/20 04:10 PM (3 years, 6 months ago) |
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The flame is bent at the angle in the photo across the whole face of the filter. I can’t find any zones of turbulence. The only turbulence I come across is while moving the lighter. I have an anemometer and it’s reading 153 fpm. I don’t trust it as it’s a cheap one and it jumps between 28fpm and 153. The 28 and the 153fpm readings are taken at a place where the lighter has a nice steady bend to the flame. This leads me to believe I should discount the anemometer. Thanks a ton.
-------------------- rad
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inski
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Re: Laminar flow hood filter damage. Hepa me! [Re: Infiniteshot]
#26831101 - 07/18/20 04:19 PM (3 years, 6 months ago) |
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It looks good to me and you are right, none of the cheap anemometers are any good for this application
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Infiniteshot
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Re: Laminar flow hood filter damage. Hepa me! [Re: inski]
#26831159 - 07/18/20 04:53 PM (3 years, 6 months ago) |
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Thanks. I appreciate your time and perspective. Have a great weekend.
-------------------- rad
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Gan
Wielder of Narya



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Re: Laminar flow hood filter damage. Hepa me! [Re: Infiniteshot]
#26831168 - 07/18/20 04:58 PM (3 years, 6 months ago) |
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Also, proof is in the pudding. Throw a few text plates in front and see if they stay clean after letting them sit for a week or so
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Infiniteshot
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Re: Laminar flow hood filter damage. Hepa me! [Re: Gan]
#26831323 - 07/18/20 06:30 PM (3 years, 6 months ago) |
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That was going to be my move. Not much loss in some agar and dishes. Thanks a bunch
-------------------- rad
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