Plumbing systems that combine copper with PP-R piping materials are appropriate as long as the flow rate within the copper components is not excessive, according to the Plastics Pipe Institute.
PPI
The Plastics Pipe Institute, Inc., (PPI), the North American trade association representing all segments of the plastic pipe industry,has announced the publication of a technical document related to the proper integration of copper tubing and components with Random Copolymerised Polypropylene (PP-R) piping materials for plumbing applications.
PPI’s TN-57 ’Proper Integration of Copper Tubing and Components with PP-R Piping Materials for Plumbing Applications’describes how improper or excessive flow rates within mixed-material plumbing systems that contain both copper materials (e.g. tubing, fittings, valves) combined with PP-R piping materials can result in premature failure of both the copper components and the PP-R materials, potentially resulting in plumbing system leaks. The problem is exacerbated by operating the system above 60°C for extended periods of time.
“In mixed-material plumbing systems which combine copper with PP-R piping materials, it is critically important to limit flow velocities through each copper component to ensure that flow-accelerated corrosion of the copper components will not result,” explained Lance MacNevin, Director of Engineering for PPI's Building and Construction Division. “This is important for the longevity of both the copper and the PP-R piping materials.”
TN-57 explains the reasons for this potential concern and how plumbing designers can avoid issues that cause this kind of failure. It can be accessed directly here and more information can be found here.