Which end of a BPF-PBCxxNL polybutylene (Poly B) transition coupling is the Poly B end?

The polybutylene end of the BPF series brass push fit transition coupling is blue for easy identification.

The Poly B end has a larger diameter insert or stiffener to support the larger inside diameter of the thinner walled polybutylene pipe. These connectors seal on the outside diameter of the pipe and can connect PB-2110 polybutylene to piping made to copper tube size (CTS). This includes copper, CPVC, and PEX pipe. ASSE 1061 push fit fittings are easy to install and do not require specialized tools for installation.

For more information on polybutylene like,

• WHAT IS POLYBUTYLENE PIPE?
• WHAT ARE THE ISSUES WITH POLYBUTYLENE?
• HOW DO YOU IDENTIFY POLYBUTYLENE PIPE?
• REPLACING POLYBUTYLENE

check out this blog post: https://blog.boshart.com/what-is-polybutylene-pipe