Pentair #2-111 Air Bleeder Adapter O-Ring

The Pentair #2-111 Air Bleeder Adapter O-Ring (part number 98209800 or 98209800Z) is a precision-molded elastomeric sealing component engineered specifically for the manual air relief valve and adapter assemblies of Pentair Clean & Clear, Clean & Clear Plus, Predator, FNS Plus, and Quad D.E. pool and spa filtration systems. Molded from a premium, high-density synthetic nitrile rubber (Buna-N), this small circular gasket conforms to standard AS568 dash-number 111 dimensions, featuring an inner diameter of approximately 7/16 of an inch and a cross-sectional thickness of 3/32 of an inch. Its primary structural role is to seat tightly within the machined perimeter groove of the air bleeder adapter stem, establishing an absolute airtight and watertight compression boundary when the valve is threaded hand-tight into the peak of the pressurized filter tank dome. This specialized seal ensures the filtration vessel can safely maintain continuous hydraulic operating pressures up to 50 PSI without slow weeping, air leaks, or pressure drops. Engineered to resist flattening under continuous mechanical torque, it easily tolerates relentless outdoor UV exposure, extreme seasonal thermal shifts, and prolonged contact with harsh pool chemistry like chlorine, bromine, and winterizing acid washes. Due to its miniature, low-profile elastomer ring architecture, this individual adapter O-ring is exceptionally lightweight, carrying a nominal product and shipping weight of approximately 0.01 pounds (about 0.16 ounces).