Ive have seen the Ridgid fans before being used in a machine shop to keep cool... they deffinetly have some power and seemed very quiet considering how much airflow they produce.

I think its a little over kill though if your lookin for something like an inline 6in fan. I suppose you could connect it to a duct line though and use it. They arent cheap either... i bet they would work great connected to an 8 in duct line going to a air cooled hood/tube though.