In a brainstorming mood? I’m trying to come up with a clever mechanical way to regulate the pressure in the exhaust duct coming from the GF. Here’s my setup:
I have a roof-mounted industrial exhaust fan with a variable speed control (up to 1000 cfm). I plan to adjust the speed control so that there is a tiny (small fraction of a psi) negative pressure at the GF outlet while the machine is operating and the fans are on. (This may require using a bleeder opening upstream if the lowest fan setting is too large.)
The tricky part is that I want to design some mechanical apparatus that will adjust the suction at the GF outlet when it is done and its fans go off. Without this, there would be a huge increase in suction and it would likely be bad for the internal GF fans. I want just enough post-cutting suction to pull out the lingering fumes without spinning the GF fans excessively, again, a small fraction of a psi.
Of course, I could just get up and adjust the external fan or the bleeder opening every time the GF finishes, but I’d prefer an automatic solution. Any ideas? Maybe some sort of a rocking, weighted, bleeder opening?