Pentair Check Valve O-ring

The designation Pentair Check Valve O-ring typically refers to a couple of widely used sealing rings depending on the exact valve model installed in the pool system: the Pentair 2" CPVC Check Valve Lid O-ring (Part #51016200 / 263042Z), the heavy-duty FullFloXF 2.5"–3" Check Valve O-ring (Part #270116Z), or the legacy Ortega Check Valve Cap O-ring (Part #072560). Molded from premium, chemical-resistant synthetic rubber elastomers (such as Buna-N or EPDM nitrile rubber), this specialized circular gasket sits tightly within a machined groove just under the valve’s clear inspection cover or screw cap. Its primary purpose is to establish an airtight, watertight compression seal that maintains system priming, prevents high-pressure water leaks from spraying out of the top of the plumbing, and keeps external air from being drawn into the filtration line when the pool pump drops into a vacuum cycle.

Because it is a small, flexible rubber ring, its weight is virtually negligible:

• Actual Product Weight: Approximately 0.01 to 0.02 pounds (roughly 0.16 to 0.32 ounces).

• Packaged Shipping Weight: Usually listed around 0.05 pounds (less than an ounce) when shipped in a standard mailer or protective plastic envelope.

Pentair Filter Tank Bottom Replacement Tutorial provides a step-by-step visual demonstration on how to safely replace a damaged or leaking lower tank assembly on a Pentair cartridge filter system.