exhaust fan questions for shop

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- wallsterr
  
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posted
20 years ago

Mon, Feb 23, 2004 9:22 PM

I'm thinking of installing an exhaust fan in my garage/shop. Because the exterior walls are made of cinder block (cutting a 4.5" hole through both sides like a dryer vent set up with a fan attached), I was wondering if a bathroom exhaust fan would clear the smoke from welding or cutting with a chop saw and dust from sandblasting cabinet. The fans that I have been seeing exhaust around 70cfm or so. The room is approx. 21' x 11' with a 7' ceiling. Would this be enough to do the job or would I just be wasting money and time installing. Currently, I open the garage door until it clears, but then all my heat I had is gone (the garage is heated by a forced air register from the house furnace) I keep the use of flamable solvents as low as possible, so as far as creating a spark from a fan and blowing up the place has been considered. Any suggestions? walt

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- Roy J
  
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posted
20 years ago

Mon, Feb 23, 2004 10:49 PM

Do the math, if the fan is operating at it's rated capacity, it would take 23 minutes to do one air change. Since you will be getting some mix of fresh and stale air, you would be needing an hour to get it fully cleared.

You would be much further ahead trying to trap the dust and fumes at the source. The same fan might do more good if you located a

4" > I'm thinking of installing an exhaust fan in my garage/shop. Because the

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- douglasehamilton
  
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posted
20 years ago

Mon, Feb 23, 2004 11:52 PM

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- Kryptoknight
  
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posted
20 years ago

Tue, Feb 24, 2004 1:01 AM

if you're gonna chop a 4" hole, why not make a bigger hole (say 8") and get bigger CFM fan ?? use sealed motors only (hermetically sealed preferred), use respirator if possible.

it's no good to breathe welding fumes, period.

don't be fooled by CFM ratings, they just tell you how much volume it can move over time. your fresh air draw is mixing with the fumes, so your not moving all fumes at rated CFM in exchange for fresh air at same time .... you'll be diluting fumes...