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Newbie2626
Stranger



Registered: 05/14/10
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Some help with flow hood needed
#22392430 - 10/17/15 09:38 AM (8 years, 3 months ago) |
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Ok guys, i've decided to build a flow hood but i'm a bit confused with matching the blower/fan with the filter.
If the filter's air flow rating is 1200m3/h or 706 cfm, should the blower be a 1200 m3/h or 706 cfm blower?
I'm confused about this because i have have seen a few tutorials online where people use a filter with a cfm rating of 825 and a blower that's only 300cfm.
I really need my flow hood up and running this coming week and your help will be much appreciated.
Edited by Newbie2626 (10/17/15 09:40 AM)
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LogicaL Chaos
Ascension Energy & Alien UFOs




Registered: 05/12/07
Posts: 69,357
Loc: The Inexpressible...
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Re: Some help with flow hood needed [Re: Newbie2626]
#22392472 - 10/17/15 09:49 AM (8 years, 3 months ago) |
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The air filters flow rating is likely the MAX amount of air flow it can handle.
So its advised you get a blower with a lower flow rating.
Also, why not use a SAB instead of an expensive flow hood?
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micro
bunbun has a gungun



Registered: 05/09/03
Posts: 7,532
Loc: Brick City
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Why not use a bunsen burner? :V
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Newbie2626
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Registered: 05/14/10
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Last seen: 6 hours, 47 minutes
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I have SAB at the moment but it's really not comfortable to work in at all. The flow hood will just make such a big difference for me. I can get more done in a day with a flow hood also.
The filter i am getting is 610mm x 1200mm so i have quite a bit of work space. Would this fan then be fine for this filter? I can get a speed control for the fan also. This is the fan i'm thinking will work: http://hydor.co.za/images/hit.pdf The HIT 250. The 350 i think is a bit much
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micro
bunbun has a gungun



Registered: 05/09/03
Posts: 7,532
Loc: Brick City
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Re: Some help with flow hood needed [Re: Newbie2626]
#22392596 - 10/17/15 10:13 AM (8 years, 3 months ago) |
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logical chaos was right on
it's a rating
so, the max it can handle
-------------------- Any research paper or book for free (Avatar is Maxxy, a character by Mizzyam, RIP)
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Newbie2626
Stranger



Registered: 05/14/10
Posts: 248
Last seen: 6 hours, 47 minutes
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Re: Some help with flow hood needed [Re: micro]
#22392739 - 10/17/15 10:43 AM (8 years, 3 months ago) |
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Yes i understand that the rating is the max it can handle. That's not what i asked. Like i said in my first post, i'm confused because there are teks that they use a filter that has a max rating of 825 cfm and use a blower that's only 350 cfm. Hence i need help with this. Math is not my strong suite and i don't really understand how to calculate what i need for that filter.
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bodhisatta 
Smurf real estate agent


Registered: 04/30/13
Posts: 61,889
Loc: Milky way
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Re: Some help with flow hood needed [Re: Newbie2626]
#22392990 - 10/17/15 11:54 AM (8 years, 3 months ago) |
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Make a comfortable sized SAB an upside down tote isn't the only way
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LogicaL Chaos
Ascension Energy & Alien UFOs




Registered: 05/12/07
Posts: 69,357
Loc: The Inexpressible...
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Re: Some help with flow hood needed [Re: Newbie2626]
#22392999 - 10/17/15 11:57 AM (8 years, 3 months ago) |
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Just get a blower with a rating lower than the filter.
No real math involved, just get a blower with half the CFM as the filter 
Could you convert a Martha closet into a giant SAB?
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gray

Registered: 03/07/15
Posts: 127
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Re: Some help with flow hood needed [Re: Newbie2626] 1
#22393137 - 10/17/15 12:44 PM (8 years, 3 months ago) |
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Quote:
Newbie2626 said: Yes i understand that the rating is the max it can handle. That's not what i asked. Like i said in my first post, i'm confused because there are teks that they use a filter that has a max rating of 825 cfm and use a blower that's only 350 cfm. Hence i need help with this. Math is not my strong suite and i don't really understand how to calculate what i need for that filter.
The filter max airflow isn't important as long as you're not trying to exceed it. You're aiming for an airspeed of 100 feet/min out of your filter.
To determine the blower required first you need to know the size of your filter. If it's 2 square feet you need to put 200 cfm through it, if it's 4 square feet you need 400 cfm, etc.
Once you've worked that out and know how much cfm you need, you can work out what blower you need. No blower has a single cfm specification. The cfm depends on the filter resistance. Any decent filter will give it's resistance in pascals or inches/h2o. Any decent blower will have a graph in the data sheet which shows resistance vs cfm.
Once you've found a blower which can push out the required cfm at the required resistance, you're golden.
Checkout evilmushroom's build notes. I also found this blog post useful for specific purchasing links in Europe (UK).
Edited by gray (10/17/15 12:52 PM)
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Newbie2626
Stranger



Registered: 05/14/10
Posts: 248
Last seen: 6 hours, 47 minutes
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Re: Some help with flow hood needed [Re: bodhisatta]
#22396228 - 10/18/15 03:12 AM (8 years, 3 months ago) |
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Quote:
bodhisatta said: Make a comfortable sized SAB an upside down tote isn't the only way
I Don't have just a roughtote as a SAB. I have a very nice SAB but i worked in front of a friend's flow hood and it hands down the best and most comfortable. I'll post some pics of my SAB later then you'll see what i mean. I don't want to work in it anymore and want a flow hood. There's a reason people spend the money on a flow hood. It's just easier
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Newbie2626
Stranger



Registered: 05/14/10
Posts: 248
Last seen: 6 hours, 47 minutes
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Thanks for the advice.I really appreciate it
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Newbie2626
Stranger



Registered: 05/14/10
Posts: 248
Last seen: 6 hours, 47 minutes
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Re: Some help with flow hood needed [Re: gray]
#22396233 - 10/18/15 03:16 AM (8 years, 3 months ago) |
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Quote:
gray said:
Quote:
Newbie2626 said: Yes i understand that the rating is the max it can handle. That's not what i asked. Like i said in my first post, i'm confused because there are teks that they use a filter that has a max rating of 825 cfm and use a blower that's only 350 cfm. Hence i need help with this. Math is not my strong suite and i don't really understand how to calculate what i need for that filter.
The filter max airflow isn't important as long as you're not trying to exceed it. You're aiming for an airspeed of 100 feet/min out of your filter.
To determine the blower required first you need to know the size of your filter. If it's 2 square feet you need to put 200 cfm through it, if it's 4 square feet you need 400 cfm, etc.
Once you've worked that out and know how much cfm you need, you can work out what blower you need. No blower has a single cfm specification. The cfm depends on the filter resistance. Any decent filter will give it's resistance in pascals or inches/h2o. Any decent blower will have a graph in the data sheet which shows resistance vs cfm.
Once you've found a blower which can push out the required cfm at the required resistance, you're golden.
Checkout evilmushroom's build notes. I also found this blog post useful for specific purchasing links in Europe (UK).
Thanks Gray. That's exactly the information i needed to know which blower to get.
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LogicaL Chaos
Ascension Energy & Alien UFOs




Registered: 05/12/07
Posts: 69,357
Loc: The Inexpressible...
Last seen: 6 seconds
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Re: Some help with flow hood needed [Re: Newbie2626]
#22397269 - 10/18/15 11:52 AM (8 years, 3 months ago) |
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Indeed. Thats somee good info grey
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