The noise and the small pipe and the high velocity all go together.
Suction line (fan outside) is much less efficient than a pressure line
(fan inside).

You need to consider a different setup with larger tube, lower static
pressure, lower speed fan. Another option is to use a fume hood type of
box arrangement, you can get by with much lower CFM needs.

Dave, I can't do that wrote:
On Oct 28, 9:29 pm, "Paul Hovnanian P.E." wrote:

Hi Paul,

How long is the pipe? In the final analysis, its going to come down to
pressure drop for most reasonable velocities.

The 4" hose is 10' and it vents to air as there are no particulates in
the flow, it is just fume extraction. However the extractor is on the
outside end if that makes a difference. It is so bloody noisy I am
putting it outside.

Dave