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TheMustardTiger


Registered: 08/19/13
Posts: 4,700
Loc: Sunnyvale Trailer Park
Last seen: 6 years, 8 months
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Blower motor CFM
#20985452 - 12/16/14 04:47 PM (9 years, 4 months ago) |
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I recently picked up this blower motor for free from an HVAC guy at work.. I dont know much about it, but I figured this was a sign to start on the old flow hood. It's a 115 volt, 1/2 horsepower (max) at 1075 RPM. I have access to a fan and housing as well so I'm hoping this motor will get the job done. My question is how can I calculate the CFM of the complete assembly? I would imagine I would need the size of the fan blade? I'm a total noob when it comes to electrical motors so any help from a electrical nerd would be super helpful.
Sorry for the sideways pictures.. No matter how I position the camera on my phone they come out like that.


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Dew Moss
Mysterious Stranger

Registered: 03/02/14
Posts: 214
Last seen: 5 years, 28 days
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I have never quite done anything with aerodynamics calculations so I could be horribly wrong.
But If I am right you would need to find the average velocity of the air in the blower then multiply it by the area of the output.
Let me know how it works out! Or what the proper equation is..
-------------------- Everything is Relative. Books of Trade
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TheMustardTiger


Registered: 08/19/13
Posts: 4,700
Loc: Sunnyvale Trailer Park
Last seen: 6 years, 8 months
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Re: Blower motor CFM [Re: Dew Moss]
#20986342 - 12/16/14 07:48 PM (9 years, 4 months ago) |
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I think I'm just going to get a speed controller and block off some of the intake and just play around with different settings until I achieve laminar flow. This motor pulls over 7 amps and is 1/2 HP max so I think it should be powerful enough for a 24"x12" HEPA
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Dew Moss
Mysterious Stranger

Registered: 03/02/14
Posts: 214
Last seen: 5 years, 28 days
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Definitely will work, I wish I still had a few motors like that laying around. But your right in instances like these its better to just test it out and adjust to how you need it.
-------------------- Everything is Relative. Books of Trade
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TheMustardTiger


Registered: 08/19/13
Posts: 4,700
Loc: Sunnyvale Trailer Park
Last seen: 6 years, 8 months
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Re: Blower motor CFM [Re: Dew Moss]
#20986521 - 12/16/14 08:17 PM (9 years, 4 months ago) |
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Quote:
vuvffufg said: Definitely will work, I wish I still had a few motors like that laying around. But your right in instances like these its better to just test it out and adjust to how you need it.
The HVAC guy at work had like 20 boxes in his truck and I was rapping with him about how much they cost, how I could use one etc and he just gave it to me. He gets them at cost, but I looked them up and this motor I have is $96 USD. I can score a fan housing and blade from the maintenance shop too. Only cost to me is the wood and HEPA.
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Jean-Luc Picard
I only wish i was this good!



Registered: 12/30/07
Posts: 4,421
Loc: New Mexico, USA
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Without considering losses:
W = dp*q
Where:
W = motor power (watts) dp = pressure change across fan (air pressure at outlet - air pressure at inlet)(pascals, N/m2) q = volumetric flow rate (m3/s
For your convenience: 1hp = 746 watts 1psi = 27.7 in.H20 = 6894.8 pascals 1 m3/s = 2119 CFM
However, remember that your W is peak hp, and will not be constant throughout the entire range of dp...but this may help you get some ballpark figures.
peace, agmotes165
-------------------- The universe is under no obligation to make sense to you - NDT
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