What size O-Ring for ORB fitting

2515R Dude · Sep 25, 2024

Another stupid question, searched everywhere, cannot find and answer.
I have a 27 Ton splitter and it leaks at two connections on the control valve.
One is 1/2 ORB (3/4" thread OD) and another is 5/8 ORB (7/8 thread OD).
I went to NAPA at least three times to buy correct O-rings. Whatever they give me ether too thick and do not go in to the chamfer and get damaged and leak or too small and leak. Ones they gave me something which felt OK, it worked for 2-3 weeks and then disintegrated, I guess it was made out of bad materials.

Now i want to find something online but cannot find any info whit size O-rings for those particular fittings.

Any help? I'm sure there is some chart for O-rings for ORB fitting, but i cannot find it

kennyd · Sep 25, 2024

Look at the chart on this page:

https://www.hydraulicstore.com/images/pdf/SAE%20O-RING%20THREAD.pdf

So for your 5/8" ORB the number is 910N90

The 910 is the industry standard number
The N is Buna-N
The 90 is the durometer

Then you can use a resource like this to figure out what the 910 means:

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

www.allorings.com

oldtimer 66 · Sep 25, 2024

Try this link

https://www.hydraulic-supply.com/orb-fitting-adapter-o-rings-485.html?

the tube size .50 and your .62 look like the orings you would need.

Buna-N

Nitrile (Buna-N) is a general purpose material suited for petroleum oils, water, and some hydraulic fluids. It is an inexpensive popular seal that is also resistant to tears and abrasive treatment and will function in temperatures between -35 degrees Fahrenheit and 250 degrees Fahrenheit.

oldnslo · Sep 25, 2024

For the #8 SAE ORB 3/4-16 thread you need a 908

Industry standard for ORB O-rings is 9+ size of port

#6 = 906
#8 = 908
Etc.

Sometimes there will be 2 in front like 2-908