US Patent 9541228 Push-to-connect fitting

A housing for receiving a fluid conduit has an internal annular shoulder. A cylindrical first cartridge is positioned in the housing and has an internal annular groove and an outer annular groove. An O-ring in the internal annular groove provides a seal with a fluid conduit. A second O-ring is positioned within the outer annular groove to provide a seal between the first cartridge and the housing. A gripping ring is positioned adjacent and in contact with the first cartridge and has inwardly projecting annularly spaced tines for gripping and holding a fluid conduit inserted into the housing. A second cylindrical cartridge is positioned adjacent the gripping ring on a side opposite the first cartridge. The housing includes a lip at one end to engage the second cartridge for holding the first and second cartridges and the gripping ring against the annular shoulder in the housing.