Cannot figure which o-ring is needed

[Stacy-MissionViejo]

Hello,
My Pentair STA-RITE U3 skimmer float valve is missing both o-rings. I identified the larger 6" o-ring, on which the valve should sit. I cannot figure out how to order the smaller o-ring that should be installed inside the valve to lock the airflow when the float drops. It seems that Pentair does not supply this o-ring separately from the valve. My valve looks almost new, and I do not see the need to buy the whole assembly 08650-0079 unless I have no other options.
Has someone changed o-rings on this valve? I would appreciate references to their sizes, the part-number for the smaller o-ring, and the sources where you bought them.
Thank you.

 

[PoolStored]

If you have the o-ring, o-rings follow a standard. Get a caliper and measure and use the tool below. Many standard o-rings are available at ACE and better hardware stores.

AS568 O-Ring Size Chart | Standard USA O-Ring Sizes

www.allorings.com

 

[Stacy-MissionViejo]

No, I don't have the o-ring, the slot is empty.

 

[Stacy-MissionViejo]

The link is very helpful, thank you!

 

[1poolman1]

Hello,
My Pentair STA-RITE U3 skimmer float valve is missing both o-rings. I identified the larger 6" o-ring, on which the valve should sit. I cannot figure out how to order the smaller o-ring that should be installed inside the valve to lock the airflow when the float drops. It seems that Pentair does not supply this o-ring separately from the valve. My valve looks almost new, and I do not see the need to buy the whole assembly 08650-0079 unless I have no other options.
Has someone changed o-rings on this valve? I would appreciate references to their sizes, the part-number for the smaller o-ring, and the sources where you bought them.
Thank you.

Those O rings are only needed if the pool gets so low on water that the valve has to seal. Even then thy don't usually seal long and the pump runs dry. Just keep your water level up.

 

[Stacy-MissionViejo]

If anyone is ever looking to buy this o-ring, I went with Buna-N, 50A Durometer in size 299 (2-3/8" ID, 2-5/8" OD, 1/8" Width). Not sure if this is the best material option (though I think it is at least good enough), but the size 299 is perfect. I could not find individual o-rings of this size and hardness, so I ordered a pack of 10 for around $10 from Amazon. Not sure if I can share the link here, but I'd be happy to DM it to anyone who's interested.

Thank you all for your assistance.

 

[nuttyp]

Looks like THIS LINK is one of the amazon providers that sells 10-packs by the standard english number. This particular one is selling viton, seems like the quantity does not affect the price, 12-$15 a pack. But I don't know viton from buna from proton.