Terry
It is somewhat of a lengthy story. The dental equipment supplier specified copper on their drawings than told the plumber to just run PEX. (This is not part of my contract) Now that the plumbing contractor has run the pneumatic system in PEX the city questions it (will not approve it with out engineering seal or letter). I have been asked by the general contractor to see if it is acceptable but currently have no backup, code or otherwise indicating that it is. Although I was trying to work with the plumbing contractor it looks like that I am going to recommend that he replace it with copper.
It is an interesting situation and I plan to contact the Pastic pipe and fitting association (PPFA) of which I delt with before years ago when PPFA wanted me to recommend them as an acceptable CISP replacement in the Army Corps of Engineers Guide specifications of which I had not problem with.
Thanks Terry for you response. As usual my approach is....Ask someone that does if for a living.