Plumbing fitting adapter

An adapter kit for fluidly coupling a tube to a threaded nipple, the adapter kit comprising:

• a nut defining a hole therethrough and configured to engage the threaded nipple;
• an adapter body extending through the hole in the nut and having:
• a first end configured to be received in the nipple and having an outer surface configured to support the threaded nipple and the nut, the first end having an annular recess extending radially inwardly from the outer surface;
• a second end opposite the first end and configured to couple to the tube;
• and
• a passageway extending within the adapter body from the first end to the second end;
• and
• a compression sleeve having a first portion located between the adapter, the threaded nipple and the nut and a second portion located completely within the recess between the threaded nipple and the adapter.

An adapter for interconnecting a tube formed of cross-linked polyethylene or chlorinated polyvinyl chloride to a threaded nipple on a valve body using a nut and a compression fitting, the adapter comprising:

• an adapter body having:
• a first end configured to be received in the nipple;
• a second end opposite the first end and configured to couple to the tube;
• a passageway extending within the adapter body from the first end to the second end;
• and
• a cylindrical outer surface proximate the first end;
• an annular recess that extends radially inward from the outer surface and is configured to receive the compression fitting;
• and
• a groove that is located between the recess and the first end and is configured to receive an O-ring,
• wherein the recess has a rectangular cross-sectional shape and the threaded nipple is configured to overlie the recess when assembled such that a portion of the compression fitting is trapped between the threaded nipple and the adapter.