Hi Brent - go to the Psub archive folder search together for the two words : PVC smash There are a file : "sub bouyancy" that may give you some answer.. Carsten Brent Shaw schrieb: > > I put up for discussion the use of abs and pvc-u > plastics for ballast control piping and valves in an > ambient design. > > No one game enough to comment > > Brent