I have a half-union 2" PVC ball valve that's missing its o-ring. I think the valve was made by Hayward. The logo on it is an "H" with waves through the middle. What's the best way to find a replacement o-ring? Are these things standard? Can I walk into a pool shop and tell them I need a replacement o-ring for a 2" Hayward half-union ball valve?
My best guess was to use a micrometer to measure the diameter at the bottom of the groove where it sits and the inside diameter of the part that it has to seal against. That would give me inside and outside diameters. What I don't know is where to go to buy the o-ring. Pool store? Plumbing store? Internet?