I'm not sure why anyone would want to consider using an unapproved piping material in any sprinkler system. Is the cost saving so great? The material content in the piping alone for a typical residential system is quite small, and all of the approved materials are quite easy to install. In view of this, why take the risk? As a matter of interest, I'm not aware that any piping material has been tested and/or approved for use on water mist systems. No doubt our water mist system members will let me know if I'm wrong. ===================================================================== Residential Sprinkler Forum Archives: //www.freelists.org/archives/dd251 WebSite: www.dd251.org.uk To unsubscribe from the list, send an email to dd251-request@xxxxxxxxxxxx with ?unsubscribe? in the Subject line or unsubscribe from the website www.dd251.org.uk