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fan for flowhood?


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6 replies to this topic

#1 MurCurY

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Posted 18 March 2006 - 12:40 PM

there's no cfm rating...but the air force blew me across the room.

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#2 WeedyResin

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Posted 18 March 2006 - 12:43 PM

Looks like about 600 cfm... there's a post for the calculation here somewhere. Sorry man, I'm stoned and too lazy to find it for you!

#3 BuckarooBanzai

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Posted 18 March 2006 - 05:23 PM

Looks like a good blower. You should get yourself an AC motor speed control. Running a blower that big will make holes in your HEPA. DON'T USE A REGULAR LIGHT DIMMER. A proper speed control will be in the $30-$50 range.

Start with the controls turned down way low. Put a lit candle in front of the HEPA (about 4 inches away) and turn up the speed control until the candle flame looks like this:

http://mycotopia.net...52&d=1136040458

The candle flame should be almost horizontal when airflow is correct.

Here is a motor speed control, mounted in a weather proof box. I highly recommend getting a box with a cover to avoid accidentally changing the speed setting. AC fan speed control:

http://mycotopia.net...51&d=1136040458

Never run an AC fan at less than %30-%40 power. You can damage the motor by running it too slowly.

Here is a thread on creating a laminar flow workstation from Rubbermaid tubs:
http://mycotopia.net...read.php?t=6707

#4 MurCurY

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Posted 18 March 2006 - 06:24 PM

why do you suggest NOT using a dimmer switch?

#5 BuckarooBanzai

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Posted 18 March 2006 - 07:34 PM

Dimmers are actually just beefy transistors with a variable resistor (potentiometer) to change voltage levels. They work by varying voltage. A light dimmer will "leak" amperage, even at low voltage levels, to a high resistance load like a blower. Excessive amperage will lead to heat build up, made all that much worse by the fan only running at 1/2 speed to remove that heat. Also, the amperage load of a decent sized blower will fry a light dimmer pretty quickly.

A proper speed control will vary voltage AND current simultaneously (motor speed controls use rheostats, not potentiometers). If you just vary voltage, you will get a lot of heat bulidup (and grease breakdown, and finally, failure) in the blower..

A light dimmer will work, but it will put a lot of extra strain on the blower.

#6 Hippie3

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Posted 18 March 2006 - 07:50 PM

save money by doing it right
in the long run.

#7 BuckarooBanzai

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Posted 18 March 2006 - 08:08 PM

I remember you mentioning something about having Plexiglass to work with. Regardless, here is laminar flow station that has worked extremely well for my FOAF:

http://mycotopia.net...read.php?t=6707

PLEASE send us pics and success rates from your new hood...




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