I am trying to build a sanding table to use in a high school woodshop. I have been searching for the right fan/blower for quite a while. I have talked to a cabinet shop who uses a rear draft design and a 5-7hp motor (this was about all the info I could get out of them). I cannot seem to find a fan for less than $5000, mainly because I think it needs to be hazard-proof. I have spoken to many fan/blower vendors and am out of ideas. Any thoughts on fans, vendors or tables anyone is already using would be appreciated. I have considered a commercial downdraft, but want a bigger area to sand in.
From contributor B:
Many people use furnace blowers for this purpose. There are even some commercially available units with furnace blowers.
Dust is taken care of by filters below the sanding surface. This gets out enough of the dust so as to basically protect the motor area from explosion. I'm not sure if the motors are totally enclosed or not.
Your next problem will be what to do with all the air blasting out of it. Mine is about 2400 cfm and it is only 1 hp! 5+ hp would have to be ducted away somewhere. Do it so that a cross-shop airflow is created, thereby cleaning the air constantly. Mine is ducted into the shop's basement, creating an airflow up the open stairwell and back into the shop. This also helps to cool the shop. You need to talk to an HVAC supplier and get the cfm ratings for different motor/blower combinations. I think 2 or 3 hp is plenty. Make sure your filter medium is 1 micron, otherwise you will create a huge fine dust blower. Very unhealthy. Hope this helps. Mine has been working daily, on all day, for 3 years. Old motor (circa 1960) died this spring. New motor will last another 5+ years I'm sure.