I'm setting up my new (to me) Trotec Speedy 300 CO2 80w (with air assist) in my home office and trying to determine the best way to vent the exhaust outside.

I have searched this forum and read a bunch of previous posts. Based on my reading, I think an inline fan may be the right solution.

It is my plan to go up vertically through the ceiling and out the roof using 4 to 6" rigid metal pipe except for a short "whip" of flexible metal at the machine.

It would be a total run of 25 to 30 feet with the fan in the middle (unless it's better to place it elsewhere). I've used Fantech's FG series for remote kitchen & bath vents in the past but am open to other brands.

Trotec is recommending 500 cfm at 6 inWG at the machine port. This is for a 3" port and mine actually has a 4" fitting if that matters. It's been difficult to get any info from them beyond this.

Because the laser is located in air conditioned space (hot, humid Houston, Texas), I do not want to oversize the exhaust. Obviously, I don't want to undersize it either as that creates all kinds of problems. I need to get this right so I get the smoke out without drawing all the air conditioning out as well.

I was concerned to read that axial fans (aka inline) can gum up with suspended particles. I'm not sure if this is also an issue for centrifugal fans but they seem to move too much air.

Has anyone else done it this way? Am I on the right track or the wrong track?

Any suggestions would be greatly appreciated.

Thanks!

Joe