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impgl
CrimethINCspecial agent

Registered: 02/07/06
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Flow Hood Specs help?
#5448502 - 03/27/06 06:01 PM (17 years, 10 months ago) |
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My 12" x 24" HEPA just came in the mail from fungi perfecti. does anyone know if a 465 CFM squirl cage is enough to power this or should I go for the suggested 495 cfm?? (like on here: http://www.thenook.org/archives/tek/flowhood.html ) I have used these flow hoods with success. any other suggestions? other flow hoods seem a lot more technical. thank you shroomery
Edited by impgl (03/27/06 07:23 PM)
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impgl
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Re: Flow Hood Specs help? [Re: impgl]
#5449662 - 03/27/06 11:57 PM (17 years, 10 months ago) |
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hrm. bumpidy bumb bumb : )
-------------------- omg really?
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Anno
Experimenter



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Re: Flow Hood Specs help? [Re: impgl]
#5449680 - 03/28/06 12:06 AM (17 years, 10 months ago) |
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Depends on the blower static pressure curve.
You might want to check http://www.fungifun.org/English/Flowhood for a more detailed description of the specifications.
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RogerRabbit
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Re: Flow Hood Specs help? [Re: Anno]
#5450715 - 03/28/06 10:32 AM (17 years, 10 months ago) |
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1" of static pressure is a pretty close rule of thumb for us to use. Most squirrel cage motors have the labled CFM determined at 1". Filters range from .8 to 1.25 or so.
Based on that, your 465 CFM blower will give just over 200 linear feet per minute of 'airspeed' leaving your blower. That is fine, if not a bit too much. If you have a bit of excess airflow, you can either get a motor speed controller, or simply block off part of the intake, or even use a prefilter to restrict the volume of air. The correct airflow will be achieved when you can light a cigarette lighter in front of the hood and it bends the flame over 90 degrees, but doesn't blow it out. 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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agar
old hand


Registered: 11/21/04
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Re: Flow Hood Specs help? [Re: RogerRabbit]
#5450846 - 03/28/06 11:01 AM (17 years, 10 months ago) |
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Agar's high tek air flow calibrator 
 OFF
 ON
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impgl
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Re: Flow Hood Specs help? [Re: agar]
#5453213 - 03/28/06 09:39 PM (17 years, 10 months ago) |
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geeze thanks! how far must the flame be in order for the 90 degree tilt to occur?
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RogerRabbit
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Re: Flow Hood Specs help? [Re: impgl]
#5453461 - 03/28/06 10:45 PM (17 years, 10 months ago) |
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It should look exactly like Agar's pic. That is the correct amount of airflow. 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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impgl
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Re: Flow Hood Specs help? [Re: RogerRabbit]
#5454721 - 03/29/06 11:04 AM (17 years, 9 months ago) |
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Quote:
RogerRabbit said: 1" of static pressure is a pretty close rule of thumb for us to use. Most squirrel cage motors have the labled CFM determined at 1". Filters range from .8 to 1.25 or so.
Based on that, your 465 CFM blower will give just over 200 linear feet per minute of 'airspeed' leaving your blower. That is fine, if not a bit too much. If you have a bit of excess airflow, you can either get a motor speed controller, or simply block off part of the intake, or even use a prefilter to restrict the volume of air. The correct airflow will be achieved when you can light a cigarette lighter in front of the hood and it bends the flame over 90 degrees, but doesn't blow it out. RR
is this to mean the thickness of my filter rabbit? because i believe mine is like 5.8 " thanks
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impgl
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Re: Flow Hood Specs help? [Re: impgl]
#5454832 - 03/29/06 11:34 AM (17 years, 9 months ago) |
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did some more research. seems to be a commonly asked question, so im just going to go with the 465 cfm. thanks for your time!
-------------------- omg really?
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mogur
regnartS

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Re: Flow Hood Specs help? [Re: impgl]
#5454967 - 03/29/06 12:20 PM (17 years, 9 months ago) |
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Quote:
impgl said:.... is this to mean the thickness of my filter rabbit? because i believe mine is like 5.8 " thanks
Well, you have decided, but I can't resist answering your question anyway, since others may be wondering, also. Nooo, the physical thickness of the filter is not part of the calculations for airflow. Static pressure is a value determined by the manufacturer by testing, and is expressed in inches, but is not related in any way to the actual thickness of the filter. It is a measure of the difficulty in pushing air through the filter. Go to the site linked by RR and see the math involved. The amount of air moved by the fan is reduced by the filter. You must use manufacturer's published charts/graphs to determine final airflow. Not very difficult, but if math turns you off, then use RR's and agar's right angle flame test. The idea is that you want your workspace air swept clean of contams by a steady stream of clean air. Too slow, and baddies can fall through the stream of air. Too fast, and turbulence will allow contams to be 'mixed' into the stream.
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Jack_Straw
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Re: Flow Hood Specs help? [Re: mogur]
#5492996 - 04/08/06 01:12 PM (17 years, 9 months ago) |
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check out this, it's for a vacuum cleaner but I wonder if it would work as a flowhood filter!
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Jack_Straw
ROC

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Re: Flow Hood Specs help? [Re: Jack_Straw]
#5493121 - 04/08/06 01:43 PM (17 years, 9 months ago) |
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RogerRabbit
Bans for Pleasure


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Re: Flow Hood Specs help? [Re: Jack_Straw]
#5493739 - 04/08/06 04:55 PM (17 years, 9 months ago) |
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No. There's a huge difference between a 6 inch thick ceramic filter that will deliver laminar flow and a vacuum cleaner filter that's designed to help cut down on your allergies after cleaning house. Don't be deceived by the words 'hepa' on products. 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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Jack_Straw
ROC

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Re: Flow Hood Specs help? [Re: RogerRabbit]
#5494896 - 04/08/06 10:29 PM (17 years, 9 months ago) |
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OK, just thought the "bacterial guard" was interesting.
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