Joining Method PEX

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There are several types of fittings for joining PEX. The various types of fittings are governed by ASTM specification. The "print stream" on PEX tubing indicates the applicable ASTM fitting specification suitable for that tubing. 

ASTM F1807 (metal) and F2159 (plastic) fittings are PEX fittings with gripping barbs that are inserted into the tubing and crimped in place using a copper crimp ring. ASTM F2089 stainless steel press sleeves and/or stainless steel clamp with ears (Oetiker clamp) can also be used with these fittings. Because these fittings are inserted, they have a smaller inner diameter than the PEX tube into which they are inserted. This causes a restriction in flow and may require the pipe to be upsized. This is the only type of fitting that can be used with PEX-B, but it can also be used with PEX-A and PEX-C. When stainless set

In the ASTM F1960 system, fittings with gripping barbs look similar to F1807 fittings, but are larger, with the same inside diameter as the tubing. The larger diameter results in a lower pressure drop through the fitting than the F1807 type. These fittings require the PEX pipe to be expanded in order to fit. To make the joint, a special PEX ring is slid over the end of a piece of PEX pipe. Both the pipe and ring are then expanded using a manual or powered expansion tool. When the tool is removed, the expanded pipe/ring is slid over the fitting. As the pipe/ring contracts around the fitting, the joint is complete. This joint will strengthen over time as the PEX contracts.  This system should only be used in temperatures above 5 °F (-15 °C).

The ASTM F2080 system is similar to F1960, except a metal compression sleeve is placed over the PEX pipe rather than a PEX ring. After the PEX tubing is expanded and the fitting is inserted, the compression sleeve is drawn down over the tube. This is the considered the most secure PEX connection. However, both an expansion tool and a press tool are required. 

The ASTM F2854 specification covers push fit fittings for PEX. To install, the PEX pipe is cut square, cleaned, and deburred. It is then simple pushed into the fitting until it reaches the stop. As it is pushed in, it passes a “grab ring” with teeth that grip the pipe to prevent it from being pulled back out. It next passes an O-ring which is compressed and seals the joint. The stop ensures that the pipe is pushed in far enough. These fittings are rated for 200°F and 200 psi. They can also be used underground if wrapped and can be installed in a wall without an access panel. The fitting can be removed using a special tool that releases the teeth so the fitting can be pulled off.

Relevant Materials And Systems

Purple Non-Potable Water Pipe

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