Pentair 2" #2-137 Buna N-70SH Upper Bulkhead O-Ring

The Pentair 2" #2-137 Buna N-70SH Upper Bulkhead O-Ring (part number 270104 or 270104Z) is a specialized elastomeric sealing component designed specifically for the upper bulkhead and multiport valve connection assemblies of Pentair Triton, Tagelus, and Sand Dollar pool and spa sand filtration systems. Molded from a premium, high-density 70 Durometer Shore A (70SH) synthetic nitrile rubber (Buna-N), this circular gasket conforms to standard AS568 dash-number 137 dimensions, featuring an inner diameter of approximately 2.06 inches and a cross-sectional thickness of 3/32 of an inch. Its primary structural role is to seat tightly within the machined perimeter channel of the 2-inch upper bulkhead fitting, establishing an absolute airtight and watertight compression boundary when the plumbing union or valve is bolted to the filter tank. This industrial-grade hardness ensures the seal can continuously withstand high-velocity water flow and internal system operating hydraulic pressures up to 50 PSI without weeping, pinching, or experiencing structural blowouts. Engineered to maintain its elastic shape memory under heavy mechanical torque, it completely resists degradation from intense outdoor weathering, severe seasonal temperature shifts, and prolonged contact with pool chemicals like chlorine, bromine, and winterizing acid treatments. Due to its streamlined, low-profile elastomer architecture, this individual bulkhead washer carries an exceptionally lightweight net product and shipping weight of approximately 0.02 pounds (about 0.32 ounces).