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mushpunx
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Re: Repeated failure with flow hood [Re: micelio] 2
#22483639 - 11/05/15 10:34 PM (8 years, 2 months ago) |
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Iboth no man Id just build a new hood. If your blower is wrong for a 24 x 24 x 12 it will be wrong for 24 x 24 x 6. I know the plenum would be right but that's it if you are are changing out blower too that's another story. You could actually use your existing blower and hood as a scrubber for a room
Both 12" and 6" will be the same for everything except plenum depth. It doesnt matter what the HEPA is you will still be figuring for 1" resistance and .2" for pre filter.
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Cue
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Re: Repeated failure with flow hood [Re: mushpunx]
#22484386 - 11/06/15 04:01 AM (8 years, 2 months ago) |
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Agreed. Went and ordered a new fan and filter. Will probably run the other one as the room filter until we're milking again come springtime. Then I'll steal it for the vacuum pump. Thanks for all your help.
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shroombasa
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Re: Repeated failure with flow hood [Re: Cue]
#22543787 - 11/18/15 08:05 PM (8 years, 2 months ago) |
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I realize this is a little bit of an old thread, but I think I've found the reason you're having FH issues and I wanted to chime in. Full disclosure, I'm only in the process of building a FH now and I've never owned one. However, I do have a science degree and have worked as a math teacher, so my comments are simply coming from my education in those disciplines, not my knowledge of mycology.
You stated your filter is 24" x 24" x 12", for a total of 4 square feet of surface area. Per Stamets, your ideal linear flow should be 100 FPM. In your situation, this equates to a volume/minute of 400 CFM (4 square feet x 100 FPM).
The Astrocel brochure you posted references two models in the airflow graphs on page 3, the Astrocel I and the Astrocel I HCX. I'm assuming you have the Astrocel I and not the HCX. At 400 CFM (according to the graph), your filter experiences ~.35" of static pressure. From RR, your static pressure should be between .8" and 1.2" to achieve laminar flow.
Quote:
Cue said: The filter actually says .9", the .96" was from the Dayton spec sheet for the fan
The label on the filter is correct. However, the line underneath the static pressure indicates that this was calculated at a Test Flow of 1000 CFM, two and a half times the amount of airflow you want. That's why your flame is blowing out. Static pressure of the filter depends on the amount of air being forced through, it's not a fixed quantity. When you drop that 1000 CFM down to 400 CFM, you've decreased your CFM to 40% of the Test Flow. Because Airflow vs. Pressure is fairly linear, you've also decreased your pressure to 40% of .9" (or .36"). This is in line with what the manufacturer graph says.
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mushpunx said: Both 12" and 6" will be the same for everything except plenum depth. It doesnt matter what the HEPA is you will still be figuring for 1" resistance and .2" for pre filter.
With respect to your post count, the 12" and 6" gives the filter very different characteristics. From page 1 of the brochure, the 6" model (5 7/8") achieves 1.0" @ 125 FPM (this equates to 500 CFM for a 4 sq. foot filter). The 12" (11 1/2") model achieves 1.0" @ 250 FPM (this is 1,000 CFM). This is what micelio was alluding to earlier,
Quote:
micelio said: From what I understand is: The 12"deep Hepa filter is for filtering rooms. It lets twice the air through than the 6" filter. That could be why you have high velocity without much back pressure (Static pressure)
...These filters are 6" deep.. I'm not sure if you can get laminar flow with the 12" deep filter with this blower..
Fortunately, as I stated above, Airflow vs. Pressure is a fairly linear relationship for filters (e.g. double the airflow, double the pressure/halve the airflow, halve the pressure), so we can assume that if we reduce the airflow for the 6" Astrocel by 20%, a 20% reduction in pressure will occur. From the characteristics of the 6" filter listed above, 1.0" @ 125 FPM becomes .8" @ 100 FPM, which is within the ideal range of pressure and airflow for a flow hood.
Unfortunately, blower CFM vs. Pressure isn't really linear (like you said, .96" for the blower equates to 200 CFM). If you plan on using a pre-filter that adds .2", this fan won't cut it. However, at .8", I imagine your blower is right at the 400 CFM mark. If you're willing to ditch the pre-filter and eliminate the extra .2" that it adds, your blower is probably perfect for the 6" Astrocel I.
For what it's worth.
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mushpunx
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Re: Repeated failure with flow hood [Re: shroombasa]
#22544216 - 11/18/15 09:33 PM (8 years, 2 months ago) |
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I dunno man Im pretty sure you could achieve laminar flow with the 12" thick HEPA , you just need a deeper plenum. At least the very least 12" in the plenum to create an even static pressure within, without turbulence. More would be better.
I think that a 24x24x12 would do just fine with a blower matched to a 24x24x6, provided you build the hood with a larger plenum.
Thats the way I undetstand it haha. Honestly I dont pretend to have past a basic knowledge of this stuff. I built my hood and it works beautifully and I am grateful for that haha
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eatyualive
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Re: Repeated failure with flow hood [Re: mushpunx]
#22544271 - 11/18/15 09:48 PM (8 years, 2 months ago) |
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is that you cue?
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shroombasa
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Re: Repeated failure with flow hood [Re: mushpunx]
#22544606 - 11/18/15 11:02 PM (8 years, 2 months ago) |
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Quote:
mushpunx said: I dunno man Im pretty sure you could achieve laminar flow with the 12" thick HEPA , you just need a deeper plenum. At least the very least 12" in the plenum to create an even static pressure within, without turbulence. More would be better.
I think that a 24x24x12 would do just fine with a blower matched to a 24x24x6, provided you build the hood with a larger plenum.
Thats the way I undetstand it haha. Honestly I dont pretend to have past a basic knowledge of this stuff. I built my hood and it works beautifully and I am grateful for that haha
I really hadn't thought a whole lot about the size of the plenum. That's good food for thought.
That's awesome that your flow hood is working for you. Like I said, I don't have one (yet), so I can't help but envy your freedom not having to G2G in a SAB.
The filter is the biggest issue I've been having. I can't seem to find anything reasonable in a 2' x 2' that has enough static pressure at low airflow.
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mushpunx
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Re: Repeated failure with flow hood [Re: shroombasa]
#22545078 - 11/19/15 01:47 AM (8 years, 2 months ago) |
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Well what I've been told is the filters dont have a static pressure. The static pressure listed on every filter is what they tested at when using a particle counter to confirm its quality.
What you probably want is a 24 x 24 x 6 HEPA, build a hood with at least a 6" plenum (Id go bigger) and a blower that blows at least 400 cfm at an SP of 1.2 (.2 added for the prefilter) .
Fungi Perfecti charges too much for the blowers but the filter price is fair.
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SpitballJedi
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Re: Repeated failure with flow hood [Re: micelio]
#22545127 - 11/19/15 02:43 AM (8 years, 2 months ago) |
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I'm a little late to the party, but here are the specs for that filter from FP: The 24x24x5.8 Filter info: HEPA-SEP Model STD 242405PEADC50 584 @ 1.0" max. w.G. Pressure Drop DOP .010max 99.99% Efficient
It's hard to say with certainty if the 1TDT5 blower is enough because it doesn't show in the specs and I wouldn't automatically count on it, but the pattern looks close.
Based on my basic understanding, the 12" filters aren't recommended for hoods because they loose their effectiveness, or efficiency, at the air velocity or volume (not sure which is technically correct) needed for 100cfm laminar output.
The more air pressure you put on filters, the less effective they are because smaller particulates can be pushed through. If I understand what I've researched, the lower SP of 12" filters are more susceptible to increased air flow inefficiencies. I imagine this becomes more of a problem over time as the layers get build-up.
I'm still trying to get a firm grasp on this because the lower SP of the 12" means lower air volume or velocity required. The only way I can think to explain this is "that goes to show how much more susceptible they are."
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mushpunx
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Re: Repeated failure with flow hood [Re: SpitballJedi]
#22545302 - 11/19/15 05:47 AM (8 years, 2 months ago) |
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Hey SBJ!
I was confused on this vefore and this is how it was explained to me:
"The filter itself does not have a static pressure. the static pressure we are concerned with is in the plenum.
12" filters are not good because you need at least 12" in the plenum to create an even static pressure within, without turbulence.
a 6" filter only requires 6" in the plenum, or more. obviously more is better.
a 12" filter will have a longer working life than a 6" filter.
the sp listed on every filter is what they tested at when using a particle counter to confirm it quality."
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SpitballJedi
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Re: Repeated failure with flow hood [Re: mushpunx]
#22545355 - 11/19/15 06:30 AM (8 years, 2 months ago) |
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It's a weird thing that apparently HVAC guys have a hard time explaining to customers, too.
The filter doesn't have a static pressure, but there is a measure of how much resistant the filter has to airflow, and that measurement is refereed to as static pressure.
I've found many explanations similar to this one.
http://www.pureairsystems.com/Pure-Air-University-103-Filtrat1.html
"Static Pressure - Pressure Drop - Resistance the Most Important Variable in Air Filter Application and Air Handler Design
Okay, so you've heard about pressure drop or static pressure or resistance as it relates to air filters or perhaps even duct work. Well…..listen up. Static pressure or resistance affects EVERYTHING in air handling. It is the ONE variable that dictates the design and performance of any air moving device and the air filters that are used in those devices.
Simply stated, pressure drop or static pressure is the amount of resistance as measured in inches of water (w.g.), that is produced when air is moved through an air filter, an air duct or any device that can impede the air flow and cause resistance."
As it pertains to hoods, the static pressure, as a measure as described above, is how the pressure will build up in the plenum. The plenum is to build pressure evenly, with low turbulence, behind the filter so you have laminar flow coming out the front. A filter with a low SP, such as .1 of a pre-filter, will allow very little pressure to build in the plenum.
I'm not an expert by any means, but this is my understanding and I'm certainly open for correction. The guy at FP told me filters don't have an SP and offered the same explanation you did and IIRC, RR has said the same thing. I imagine the truth lies in a combination of both our understandings.
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shroombasa
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Re: Repeated failure with flow hood [Re: SpitballJedi]
#22545489 - 11/19/15 07:31 AM (8 years, 2 months ago) |
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"Filters don't 'have' static pressure. They apply a resistance across the airflow which causes the static pressure.
Filters are usually rated by how much flow will pass through the filter at a given static pressure. (resistance) RR"
RR is more or less arguing over the semantics of using the word "have" to describe filters and pressure. It's like saying that a cloud "has" rain. Air flowing through a filter causes static pressure; cold air combining with a cloud causes rain. These things are effects we observe, not intrinsic properties.
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mushpunx
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Re: Repeated failure with flow hood [Re: SpitballJedi]
#22545491 - 11/19/15 07:33 AM (8 years, 2 months ago) |
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Honestly dude I have a very limited understanding of this stuff too and you're probably right I think it's some of both of our understandings.
I still think the math would work out the same though, you could match a blower that blows at least 400CFM at 1.2sp to a filter that is 24 x 24 x 12, if you built the hood with a plenum of a depth greater than 12"
Cool info you guys are posting! Im trying to understand this stuff myself. A lot of people ask me about my flow hood and the only advice I can offer is pretty basic stuff about the actual hood build and wiring, stuff like that. I can figure out how to match blowers and fans but that's it 
I dont see you in Mush Cult much anymore dude I miss your input!
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invitro


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Re: Repeated failure with flow hood [Re: mushpunx]
#22545581 - 11/19/15 08:15 AM (8 years, 2 months ago) |
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drake89 uses a 12" deep hepa I believe, he hangs out on the GMM forum. I think he could clear things up.
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micelio
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Re: Repeated failure with flow hood [Re: SpitballJedi]
#22546740 - 11/19/15 01:02 PM (8 years, 2 months ago) |
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Quote:
SpitballJedi said: I'm a little late to the party, but here are the specs for that filter from FP: The 24x24x5.8 Filter info: HEPA-SEP Model STD 242405PEADC50 584 @ 1.0" max. w.G. Pressure Drop DOP .010max 99.99% Efficient
It's hard to say with certainty if the 1TDT5 blower is enough because it doesn't show in the specs and I wouldn't automatically count on it, but the pattern looks close.
Based on my basic understanding, the 12" filters aren't recommended for hoods because they loose their effectiveness, or efficiency, at the air velocity or volume (not sure which is technically correct) needed for 100cfm laminar output.
The more air pressure you put on filters, the less effective they are because smaller particulates can be pushed through. If I understand what I've researched, the lower SP of 12" filters are more susceptible to increased air flow inefficiencies. I imagine this becomes more of a problem over time as the layers get build-up.
I'm still trying to get a firm grasp on this because the lower SP of the 12" means lower air volume or velocity required. The only way I can think to explain this is "that goes to show how much more susceptible they are."
Here's the Technical Specs for the 1TDT5 blower:
http://www.grainger.com/product/DAYTON-Rectangular-OEM-Blower-Without-1TDT5?nls=3&ssf=3&searchQuery=1TDT5
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SpitballJedi
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Re: Repeated failure with flow hood [Re: micelio]
#22548685 - 11/19/15 08:00 PM (8 years, 2 months ago) |
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the specs only show CFM up to .6" Sp.
Some fans drop off dramatically at higher SP. I wouldn't spend that much money unless I could verify it will work first.
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shroombasa
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Re: Repeated failure with flow hood [Re: SpitballJedi]
#22550870 - 11/20/15 10:09 AM (8 years, 2 months ago) |
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Quote:
SpitballJedi said: the specs only show CFM up to .6" Sp.
Some fans drop off dramatically at higher SP. I wouldn't spend that much money unless I could verify it will work first.
Dramatically, indeed. http://www.electricmotorwarehouse.com/content/Dayton/blower_specs/ITDT5.pdf
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Cue
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Re: Repeated failure with flow hood [Re: shroombasa]
#22556248 - 11/21/15 04:25 PM (8 years, 2 months ago) |
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Just to button up, I had bought a fan that would supply the required amount of airflow (believe it was the 1tdu2 but I'm not looking at it now) and a 24x24x6" filter. Constructed a few days ago. Worked in front of it today, but leaving on vacation for a week. Will know how everything turned out when we get back. Perhaps I will have photos.
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Cue
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Re: Repeated failure with flow hood [Re: Cue]
#22635217 - 12/09/15 06:07 PM (8 years, 1 month ago) |
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I've done 2 sets of g2g transfers since the week before thanksgiving. First set I had 75% success, I attributed the loss to removing the tin foil off the jars before cooling, second set is 100% success. Will have a less biased opinion in the future, but already these changes have made me fee a lot better.
Glad to have fixed what was causing me so much stress.
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micelio
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Re: Repeated failure with flow hood [Re: Cue]
#22635438 - 12/09/15 06:50 PM (8 years, 1 month ago) |
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Keep us updated... We all like success stories....
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mushpunx
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Re: Repeated failure with flow hood [Re: Cue]
#22636276 - 12/09/15 09:44 PM (8 years, 1 month ago) |
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Quote:
Cue said: I've done 2 sets of g2g transfers since the week before thanksgiving. First set I had 75% success, I attributed the loss to removing the tin foil off the jars before cooling, second set is 100% success. Will have a less biased opinion in the future, but already these changes have made me fee a lot better.
Glad to have fixed what was causing me so much stress.
Successfully fruited or just seems like clean spawn so far?
What do you think your problem was until this time?
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