Pentair Lid O-Ring, 3-3/4 in. ID (Viton)

The Pentair R172009 is the lid o-ring for Rainbow automatic chlorinators, models 300, 302, 320 and 322. It is made of Viton, a heavy duty fluoroelastomer that stands up to the concentrated chlorine or bromine inside the feeder body far better than a standard rubber ring.

Size

3-3/4 in. inside diameter with a 3/16 in. cross section. Compare against the old ring if you are unsure which feeder you have.

When to replace it

A feeder that weeps water at the cap or lets out a hiss of gas when the pump runs has a lid o-ring that is swollen, flattened or cracked. Unscrew the cap, roll the old ring off, seat this one in the groove and tighten the cap by hand.