Pentair #2-259 3-Port Valve Compression O-Ring

The Pentair #2-259 3-Port Valve Compression O-Ring (Product #: 071427 / 071427Z) is a factory-original OEM replacement sealing component engineered to establish an airtight, leak-proof hydraulic barrier within high-capacity pool and spa filtration networks. Specifically designed as the primary housing perimeter seal for heavy-duty, built-in side-mount backwash valves on classic Purex, Pentair, and PacFab SM and SMBW 2000 and 4000 series diatomaceous earth (D.E.) fiberglass filters (including popular models like the 4024, 4036, and 4048), this large-diameter round-profile ring sits securely within the machined channel of the 3-port valve body casting. When the valve top assembly or structural brass retaining hardware is compressed and bolted down, the gasket deforms uniformly to establish a positive pressure-side water barrier and block catastrophic suction-side air induction that would otherwise cause pump cavitation, loss of system prime, or external water weeping. Molded from a high-grade nitrile rubber (Buna-N) compound featuring a rigid 90-durometer hardness rating, the component delivers exceptional structural elasticity, superior ozone resistance, and long-term compression memory, allowing its 6.25-inch inner diameter and 1/8-inch cross-section thickness to withstand continuous exposure to high chlorine or bromine concentrations, heavy pool mineral scaling, and intense thermal cycling without flattening or dry-rotting. Built to comfortably manage rapid water velocities and continuous baseline operating line pressures up to 50 PSI, this flexible part ensures the entire backwash loop operates at peak hydraulic efficiency. The physical dry product weight of this single Pentair #2-259 O-Ring is approximately 0.021 pounds (roughly 0.34 ounces, with a nominal packaged shipping weight of 0.05 pounds), providing pool service professionals and homeowners with an essential, low-cost, and highly reliable internal hardware safeguard for flawless pool water management.