O ring size/measuring

[Right-arm fast]

Hi,
I need an o ring for a hydraulic cylinder. Firstly I need to accurately measure it. How do I do this ? It’s got a largish diameter but quite a thin cross section. I have a vernier caliper. Secondly where is the best place/supplier to order one from for overnight delivery.

Tia

 

[davidroberts30]

Measure the rod for the oring inside measurement then measure the groove for the cross section

 

[Right-arm fast]

Measure the rod for the oring inside measurement then measure the groove for the cross section

Thanks DR. Is that a fool proof method of getting the right sizes?

 

[davidroberts30]

No?

 

[tomlad]

I a ram service place .
He had a gauge thing like a pirimid , with steps .were ever the ring sat was its size , id i guess, measured thickness in groves around its base.

 

[Right-arm fast]

I a ram service place .
He had a gauge thing like a pirimid , with steps .were ever the ring sat was its size , id i guess, measured thickness in groves around its base.

Hi yes have seen those. Wanted to avoid two trips to sort a single oring, think it might be safer though.

 

[davieh3350]

I measure the male size of the part, then I measure the ring, if it's squashed I measure the thick part then the thin part and split the two and it comes out close.