Insulation Vapor Barrier

[KenRad]

On chilled water pipe insulation for my industrial facility, I have used Styrofoam and Polyisocyanurate (Dow's Trymer) with PVC jacketing for years, with excellent success. All insulation joints are staggered and sealed, and all PVC seams are solvent welded. I have thousands of feet of chilled water piping, 3/4" to 10", and no problems with condensation under the styrofoam. My lowest chilled water temperature is 41F; insulation thickness is 1-1/2"; some of the piping is in conditioned space, and some is not.

I recently had one of my suppliers tell me that PVC is not an adequate vapor barrier, and that I should be using something else, like ASJ or Dow's Saran. I consulted Dow, but they will not make recommendations on vapor barrier. Can anyone shed some light on this issue?

---KenRad

 

[imok2]

Ken, Pvc in my estimation is an excellent cover for insulation; we have used it for many years with great success. Here is a good artcle on the subject:

http://www.hpac.com/member/feature/2001/0106/0106lotz.htm