Thank you both for excellent suggestions!
IRstuff, the possibility of using a Kynar coating falls under the "Geez, why didn't I think of that?" I used a similar specification on an armory years ago. It's actually more economical than it sounds. I had considered a Teflon coating, but I think Kynar is far better and no doubt less costly.
Later yesterday, I stumbled on a website for medical equipment that had pdf charts of the physical characteristics of various plastics. It's a good, concise synopsis that clearly shows that the use of LDPE would be foolhardy in this application. I downloaded the charts, printed them in color, wrote the chemical names for each of the plastics (OK, I had to Google PMP and PFA), and circled the important data, then gave it to the lead architect.
She was amazed and pleased, and this is someone who is not easy, if not impossible, to please. She'll be happy until she realizes all I've provided is what should NOT be done. But you guys have given me the #2 punch, possibilities for what CAN be done. Thanks again!
And if you are interested in the website with the charts, here's the link. Look down at the bottom of the page. There are about 4-5 lines describing "physical properties" and "chemical resisitance A-G" etc.
