O Rings are moulded circular rings with a circular cross-section. When you Compress the cross-section in a housing, you will achieve a water / airtight seal. O rings are mostly used in non-moving (static) applications. However, They can and are used on some Moving applications, such as Hydraulic rams, to give a secondary seal or rod wiping action. The O’ring would normally be fitted in a groove that’s machined or moulded in one of the surfaces to be sealed.
Nitrile O Rings have a working temperature range of -30 to +100 degrees C.
Nitrile O Rings have good chemical resistance to mineral oils and greases, hydraulic oils and also non-flammable hydraulic pressure fluids.
Viton O Rings have a working temperature range of -15 to +200 degrees C.
Viton O Rings have good chemical resistance to mineral and synthetic oils and greases, engine and transmission oils, fuel and non-flammable hydraulic pressure fluids Viton also has a very low gas permeability which makes it suitable for vacuum applications.
Silicone O Rings have a working temperature range of -55 to +200 degrees C.
Silicone has good resistance to water, aliphatic engine and transmission oil and animal and plant oils and fats. Most commonly available in either red or white but can be made in black if required.
PTFE O Rings have a working temperature range of -200 to +300 degrees C.
PTFE is the most chemically inert of all the O ring materials, it is resistant to most chemicals, acids, oils and steam. It is very tough and abrasion resistant however it is not easily compressible and will not seal as well as other polymers.