O-Ring Face Seal
O-Ring Face Seal (OFS) fittings were designed to eliminate leakage problems and still handle the greater pressure of today’s hydraulic systems, and are dimensionally standardized in SAE J1453. An OFS connection uses a Buna-N, 90 Durometer O-ring that seats into a grove in the face of the fitting. As the connection is tightened the O-ring compresses against a flat-face sleeve that is brazed onto the end of a tube, am makes a metal-to-metal seal crating a cavity that supports the O-ring. The sleeve also prevents twisting of the tube and supports it during the assembly process.