Polyethylene pipe from Centennial Plastics in three families that are not interchangeable: CenFlo for potable water, CenGas for natural gas and CenFuse for geothermal loops. Coils and sticks from 3/4" through 6".
Read the SIDR or SDR before you order fittings. This is the decision that goes wrong most often on a poly job. SIDR pipe is made to a controlled inside diameter, so it takes barbed insert fittings clamped on the outside. SDR pipe is made to a controlled outside diameter, so it takes heat fusion or compression couplings and will not seal on an insert fitting sized for SIDR. Same material, same nominal size, different fitting system.
SDR itself is a ratio, not a size: outside diameter divided by wall thickness. A lower number means a thicker wall and a higher pressure rating, so SDR 11 is heavier than SDR 17 at the same diameter.
CenFlo, potable water. Controlled inside diameter HDPE 4710, SIDR 7, rated 250 PSI, in 3/4", 1", 1-1/4", 1-1/2" and 2", on 100 ft and 300 ft coils. Built to accept the common insert fittings, and Centennial carries a 30-year warranty on it. This is the pipe for a water service from the meter to the house.
CenGas, natural gas. MDPE 2708, SDR 11, on 250 ft coils in 3/4", 1", 1-1/4" and 2", plus HDPE 4710 SDR 11 in 2". The pipe is solid yellow so it is identifiable as gas in the trench and years later at the next dig. Gas poly is joined by fusion or by listed mechanical couplings, and both the pipe and the joining method fall under the gas code rather than the plumbing code.
CenFuse, geothermal. Fusible HDPE 4710 in Iron Pipe Size, NSF 14 certified, SDR 17 rated 160 PSI, in 4" and 6" on 20 ft sticks. Made for controlled outside diameter work: geothermal loops, irrigation headers, stock water and industrial. Centennial carries a 50-year warranty on it.
Related: Flexible gas pipe · Compression fittings · Brass fittings · Sewer and drain pipe
