[Ti] [OT] process flow diagrams on a Mac

[Dr Trevor J. Hutley]

On my G4 Powerbook (so it really is on topic?) I want to create some  
process flow diagrams (PFD).
This is sort of "chemical engineering".
Diagrams that show how processes (actually for polymer production)  
are laid out and arranged.
Showing elements like pumps, compressors, pipes, etc.

It seems that Visio Technical has a template for process flow  
diagrams, but Omnigraffle (Pro) 4, which I have, does not.
It offers limited office and business templates but nothing 'technical'.

Does anyone know of any software that runs on a Mac that I could use  
for creating PFD (process flow diagrams) ?

Could be a way to create a greater presence for Mac here.

regards,  Trevor
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