Ventillation system thoughts

We have a 600 CFM ventillation system for our casting room, and we
were considering ducting that air to the back of our benches to help
decrease our intake of soldering fumes and polishing contaminants. We
have 3 stations that would be using this system and if we block off
the 10" duct work from above the burn out oven in our casting room
and all the soldering stations when not in use would there be
sufficient air flow to effectively ventilate the one or two stations
that would be in use?

We were thinking about putting a 3" PVC pipe into the 10" duct work.
The furthest soldering station would require approx. 20 linear feet
of PVC tubing and the other two are about 15 linear feet from the
casting room.

If this system would not be adequate, can you recommend a better
solution to our problem or source that may have some literature that
we could reference.

John P.
@John_P