Pentair #2-325 Drain Cap O-Ring

The Pentair #2-325 Drain Cap and Valve Stem O-Ring (Product #: 51005000 / 51005000Z) is a factory-original OEM replacement sealing component engineered to establish an absolute, leak-proof hydraulic barrier across a diverse lineup of high-capacity filtration systems and push-pull plumbing valves. This multi-use round-profile ring fits into precision-machined grooves on specialized pool and spa equipment, serving as either the foundational seal for the primary drain cap or as a critical intermediate gasket on internal moving selector stems. It is engineered for a broad range of premium Pentair machinery, including Clean & Clear® Plus and Predator® cartridge vessels, Warrior® and EasyClean® diatomaceous earth (D.E.) configurations, FNS® and Meteor® sand tanks, as well as Pentair's signature line of push-pull slide backwash valves. When compressed under physical installation torque or standard operating system loads up to 50 PSI, this elastomeric ring yields a positive mechanical barrier that blocks pressurized water from weeping out of the filter tank drain and stops catastrophic suction-side air induction that would otherwise cause pump cavitation and loss of system prime. Molded from an ultra-durable, high-grade ethylene propylene diene monomer (EPDM) rubber compound featuring a 70-durometer hardness rating, the ring delivers exceptional dimensional compression memory and superior ozone resistance, allowing it to withstand continuous exposure to high chlorine or bromine concentrations, concentrated shock treatments, and intense outdoor UV radiation without flattening, tearing, or dry-rotting. The physical dry product weight of this single Pentair #2-325 O-Ring is approximately 0.02 pounds (roughly 0.32 ounces, with a nominal packaged shipping weight of up to 0.20 pounds depending on specific retail bagging), providing pool service professionals and DIY homeowners with a vital, low-cost hardware standard to preserve optimal equipment pad circulation and baseline efficiency.