‘O’ rings are simply measured by the ID (inside Diameter) and section size. There are many options for material specifications as shown below, if you are uncertain on material requirements and common sizing consult your local branch. For convenience a range of o ring kits are available.
Nitrile (NBR) 70
The most common elastomer used for industrial grade O-rings. Compatible with most mineral based hydraulic fluids with a working temperature range from -40°C to 110°C.
Nitrile (NBR) 90
Harder than Nitrile 70 and hence suitable for use as a high pressure O-ring or back up washer.
Possessing the broadest chemical compatibility of any mainstream elastomer, its broad working temperature range of -35°C to 205°C and excellent mechanical properties make this an excellent high performance compound for use in hydraulic systems.
Silicone, EPDM, Neoprene
..and other specialty compounds are available in many sizes or to order.