#6 to 5/8-18 O-Ring Seal P/S Adapter

The #6 to 5/8-18 O-Ring Seal P/S Adapter by RUSSELL is a precision hydraulic and pneumatic fitting designed to bridge connections between AN-sized ports and NPTF metric threads in high-pressure fluid systems. This straight adapter serves as a critical coupling solution for engineers, technicians, and enthusiasts who work with custom hydraulic lines, air systems, and fuel delivery applications where reliable sealing under pressure is non-negotiable. Whether integrating aftermarket hydraulic components, upgrading brake systems, or assembling pneumatic tooling, this adapter ensures leak-free performance across demanding industrial and automotive environments.

Manufactured from aluminum in a natural finish, the adapter features male O-ring face seal (ORFS) construction on the #6 AN end and a 5/8-18 inch male NPTF thread on the opposite side, delivering a straight-through passage that minimizes flow restriction and turbulence. The O-ring seal design creates a metal-to-metal wedge contact that prevents leakage without relying solely on thread sealants, making it ideal for high-vibration or high-temperature applications where tape or Teflon can degrade. The lightweight aluminum construction reduces system weight while maintaining structural integrity, and the natural anodized surface resists corrosion in most industrial settings.

This adapter is essential for anyone assembling custom hydraulic brake lines, pneumatic pressure regulators, fuel injection systems, or industrial fluid transfer equipment that requires NPTF-threaded ports. It pairs seamlessly with standard AN hose fittings and NPTF-compatible manifolds, making it a versatile solution for both one-off custom builds and production-level assembly. Installation is straightforward—hand-tighten the O-ring fitting to make metal contact, then rotate an additional quarter turn with appropriate wrenches to achieve a leak-free seal without over-torquing. Verify thread compatibility and pressure ratings with your system specifications before installation.