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RolledUhhp
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Registered: 08/10/16
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Laminar Flow Build
#23603949 - 09/02/16 08:02 AM (7 years, 4 months ago) |
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I've been searching here and elsewhere for a few days now, and I think I've narrowed my filter/blower selection down.
I'm pretty sure I'm good to go, but I thought I'd post here and get a second opinion.
The spec sheet for the blower I have my eye on only lists CFM up to 0.8" SP, which I'm not sure how (or if I can) to calculate what it would be at 1"SP.
I'm going to be going with the 12x18x5.8" 18x24x5.8" filter from Fungi Perfecti, and I have my eye on THIS blower, found quite a bit cheaper on ebay.
I'm not asking anyone to go into tremendous detail, or rewrite any of the many guides found on the forums, but I would greatly appreciate input from someone who's been in this wallet clutching position!
Thanks for reading!
Edited by RolledUhhp (09/02/16 12:09 PM)
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sandy_vag
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Registered: 06/14/16
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Seems fine you need 150 cfm at the static pressure of your filter on a filter than size. Overkill is ok since you can easily adjust the rate down with blockage or fan controller.
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Thedillestpickle
cultured



Registered: 02/02/16
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Re: Laminar Flow Build [Re: sandy_vag]
#23604106 - 09/02/16 09:34 AM (7 years, 4 months ago) |
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Quote:
sandy_vag said: Seems fine you need 150 cfm at the static pressure of your filter on a filter than size. Overkill is ok since you can easily adjust the rate down with blockage or fan controller.
Hopefully OP doesn't mind me tacking a few extra questions on his thread...
"With blockage" meaning covering part of the intake to the blower to restrict airflow?
What is a fan controller? I used a light dimmer switch from a hardware store to adjust the speed on my home-made stir-plate(using a muffin fan), would this also work for the blower motor? If not, what sort of device would I be looking at for adjusting blower speed? I think I may have gone a bit overkill on the blower I bought for my filter(currently waiting for these to arrive in the mail)
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sandy_vag
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Registered: 06/14/16
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Yes covering part of the intake will reduce the airflow.
They make fan speed controllers specifically for electric motors, popular in the hydroponic world. A dimmer switch will not be appropriate for this. You can also use a router speed controller from harbor freight no problem, it's the same thing just china cheap.
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sandy_vag
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Re: Laminar Flow Build [Re: sandy_vag]
#23604126 - 09/02/16 09:46 AM (7 years, 4 months ago) |
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Also it doesn't have to be EXACTLY 100fpm. 90-120 is perfectly acceptable.
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RolledUhhp
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Registered: 08/10/16
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Re: Laminar Flow Build [Re: sandy_vag]
#23604442 - 09/02/16 11:48 AM (7 years, 4 months ago) |
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Quote:
Hopefully OP doesn't mind me tacking a few extra questions on his thread...
The more the merrier!
Quote:
sandy_vag said: Seems fine you need 150 cfm at the static pressure of your filter on a filter than size. Overkill is ok since you can easily adjust the rate down with blockage or fan controller.
My brain might just be on overload right now, but would we divide 150cfm by 3 to get fpm? If I'm doing this right that only gives me 50fpm coming out of the filter, about half of what we're shooting for.
I've sent an email to FP to make sure, but I believe I read that the filters available through them have a working point of 0.8"wc to achieve laminar flow.
Edit: Just received an email back from FP:
"The 24x18 HEPA filter is rated for 429 cfm at one inch of static pressure."
"is rated for 429 cfm at one inch of static pressure."
That wording confused me a bit...
Assuming I have a pre-filter at 0.2" + 1" = 1.2"wc
So my blower should deliver at least 300cfm at 1.2" for me to achieve 100fpm from my filter face?
Please point out where I'm wrong, because I'm sure there's at LEAST one mistake in this post.
Edited by RolledUhhp (09/02/16 12:07 PM)
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mushpunx
Fungus Punk


Registered: 04/20/14
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Do you mean 12 x 24 x 5.8? I dont think FP sells a 12 x 18. Mine is 24 x 18 and I got it from FP. If you meant 24 x 18 that blower is way too small.
It will be right about 200 at 1 - 1.2 sp (.2 for your pre filter.) Which will be almost perfect for a 12 x 24
That blower should be just about perfect for a 12 x 24. If you buy it on ebay make sure its the same model number so it has the same specs, not all blowers listed under the same CFM have the same output.
I haven't seen a 12 x 24" build in a while so Im looking forwards to see!
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RolledUhhp
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Re: Laminar Flow Build [Re: mushpunx]
#23604499 - 09/02/16 12:15 PM (7 years, 4 months ago) |
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I did indeed mean 24x18x5.8", I edited my OP to avoid any more confusion. Thanks for pointing that out!
I just got the manual from grainger hoping to find cfm @ 1.2"sp, but unfortunately the manual isn't any help. In fact, it doesn't list any information I'm looking for.
It'd be much easier if we could search Graingers site at different SP!
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mushpunx
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Quote:
RolledUhhp said: I did indeed mean 24x18x5.8", I edited my OP to avoid any more confusion. Thanks for pointing that out!
I just got the manual from grainger hoping to find cfm @ 1.2"sp, but unfortunately the manual isn't any help. In fact, it doesn't list any information I'm looking for.
It'd be much easier if we could search Graingers site at different SP!
I think its safe to guesstimate , just figure out how much they are decreasing by and continue up the graph. I think that blower will be fine, Im no expert but its the one I would usr
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RolledUhhp
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Re: Laminar Flow Build [Re: mushpunx]
#23604523 - 09/02/16 12:27 PM (7 years, 4 months ago) |
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Quote:
Mine is 24 x 18 and I got it from FP. If you meant 24 x 18 that blower is way too small.
Quote:
I think that blower will be fine, Im no expert but its the one I would usr
I am indeed going to be using a 24 x 18, I botched the OP, but it's fixed now.
If we're assuming I'm going to be around 200cfm with that blower at 1.2" then dividing that by 3 gives me ~67fpm, which is going to be too little here... I'll try to find something bigger in my price range, I'm sure I'll be back soon!
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Grandmother
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Registered: 07/29/16
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When you get around to wiring this specific blower you should write a tutorial. I have this sitting in my garage with no clue on how to wire it and can't find a decent picture filled tutorial despite constantly searching for one.
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RolledUhhp
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Quote:
Grandmother said: When you get around to wiring this specific blower you should write a tutorial. I have this sitting in my garage with no clue on how to wire it and can't find a decent picture filled tutorial despite constantly searching for one.
I'm not great with electrical by a long shot, but it should be pretty simple. If you can take a few pictures I'm sure we can get you straightened out.
I think we're leaning towards a bigger blower for my 24 x 18 hood, but from what mushpunx has said and if my own math is (probably not) right - that blower should work well for a 12 x 12 setup.
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mushpunx
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Wiring is a piece of cake. Mine had a cover over the wiring that had to be removed. Essentially just get an extension cord and cut the end off. Then just hook up the 2 wires and the third to the ground.. you just twist tape and cap
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RolledUhhp
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Alright, moving up the ladder a bit, I've found THIS blower.
HERE is the spec sheet on it.
It's a two speed motor, but I'm only going to be using the numbers for the higher setting to keep things simpler.
The red numbers are the loss in CFM at each increase in pressure.
- CFM @ 0.000-In. SP - 797
- CFM @ 0.100-In. SP - 780 (-17)
- CFM @ 0.200-In. SP - 730 (-50)
- CFM @ 0.300-In. SP - 720 (-10)
- CFM @ 0.400-In. SP - 680 (-40)
- CFM @ 0.500-In. SP - 640 (-40)
- CFM @ 0.600-In. SP - 620 (-20)
- CFM @ 0.700-In. SP - 560 (-60)
- CFM @ 0.800-In. SP - 500 (-60)
Now, estimating a loss of (-40,-40,-60,-60) would put me around 300cfm at 1.2" SP, but if I go "worst case scenario" and run (-60, -60, -60, -60) I come to 260cfm at 1.2", which would give me ~87fpmm - a bit too low for me to be comfortable with.
I'll keep searching ebay ect.. to find something a bit bigger in my price range that will let me err on the side of caution.
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mushpunx
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For a 24 x 18 I used a Dayton blower, 549CFM @ free air , and buily a 10" plenum behind the filter. Worked perfect
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mushpunx
Fungus Punk


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Quote:
RolledUhhp said: Alright, moving up the ladder a bit, I've found THIS blower.
HERE is the spec sheet on it.
It's a two speed motor, but I'm only going to be using the numbers for the higher setting to keep things simpler.
The red numbers are the loss in CFM at each increase in pressure.
- CFM @ 0.000-In. SP - 797
- CFM @ 0.100-In. SP - 780 (-17)
- CFM @ 0.200-In. SP - 730 (-50)
- CFM @ 0.300-In. SP - 720 (-10)
- CFM @ 0.400-In. SP - 680 (-40)
- CFM @ 0.500-In. SP - 640 (-40)
- CFM @ 0.600-In. SP - 620 (-20)
- CFM @ 0.700-In. SP - 560 (-60)
- CFM @ 0.800-In. SP - 500 (-60)
Now, estimating a loss of (-40,-40,-60,-60) would put me around 300cfm at 1.2" SP, but if I go "worst case scenario" and run (-60, -60, -60, -60) I come to 260cfm at 1.2", which would give me ~87fpmm - a bit too low for me to be comfortable with.
I'll keep searching ebay ect.. to find something a bit bigger in my price range that will let me err on the side of caution.
This blower already pushes 100CFM more than you need at 1.2CFM , you would definetly have to power it down / block the intake
I think this or the smaller one would be good, you want it to be as close as possible.
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RolledUhhp
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Re: Laminar Flow Build [Re: mushpunx]
#23604624 - 09/02/16 01:07 PM (7 years, 4 months ago) |
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Quote:
mushpunx said:

For a 24 x 18 I used a Dayton blower, 549CFM @ free air , and buily a 10" plenum behind the filter. Worked perfect
Using these specs I did the same estimation I did in my post above and subtracted ~120cfm from the 360cfm listed at 0.8" to guess where we'd be at 1.2" - I'm coming up with 240cfm or 80fpm, which is a bit on the lower side, but should be sufficient. I'd like to shoot a bit higher, but we'll see where reality takes me.
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RolledUhhp
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Quote:
This blower already pushes 100CFM more than you need at 1.2CFM , you would definetly have to power it down / block the intake
I think this or the smaller one would be good, you want it to be as close as possible.
AHA! Maybe that's where I'm confusing myself! Wouldn't I divide the cfm, in this case 300cfm by 3 to get my fpm coming out of the front of the hood?
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mushpunx
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Quote:
RolledUhhp said:
Quote:
mushpunx said:

For a 24 x 18 I used a Dayton blower, 549CFM @ free air , and buily a 10" plenum behind the filter. Worked perfect
Using these specs I did the same estimation I did in my post above and subtracted ~120cfm from the 360cfm listed at 0.8" to guess where we'd be at 1.2" - I'm coming up with 240cfm or 80fpm, which is a bit on the lower side, but should be sufficient. I'd like to shoot a bit higher, but we'll see where reality takes me.
All blowers are different Before I bought this blower I got the actual blower specs chart. It does push 360cfm at .8 sp but at 1.2 it was not 240, it was just above 300CFM. Which matches perfectly for an 18 x 24 " filter, I built my hood with a 10" plenum and I didnt have to block blower intake or power down at all it matched just right
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mushpunx
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Quote:
RolledUhhp said:
Quote:
This blower already pushes 100CFM more than you need at 1.2CFM , you would definetly have to power it down / block the intake
I think this or the smaller one would be good, you want it to be as close as possible.
AHA! Maybe that's where I'm confusing myself! Wouldn't I divide the cfm, in this case 300cfm by 3 to get my fpm coming out of the front of the hood?
For a 12 x 24" filter face you need 200CFM @ 1.0 SP. for 18 x 24 you need 300CFM, for 24 x 24 its 400CFM
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