The O'ring or toroidal seal is an exceptional versatile sealing device for various applications. The range of application begin from garden hose couplings to critical aerospace duties, make it the world's most popular seals.

The advantages of using o'rings are: suit many static and dynamic duties, occupy little space, seal efficiently in both directions, are compatible with the most fluid media, elastomeric O'rings can function between - 65 °C ÷ + 315 °C according to material type, PTFE o'rings can perform at temperatures down to - 200 °C.

Choosing an o'ring is recommended by : pressure, medium pressure, working temperature, static or dynamic operation, housing type, tolerances, other important factors.

Rubber has a very high bulk modulus and therefore virtually incompressible. This means that the o'ring must be deformed on the diameter section to give it an initial sealing force within a housing.

When system pressure is applied, the o'ring deforms further. But, because of the initial squeeze, the sealing force always exceeds on the o'ring by the system pressure.

At higher pressures, back-up rings might be required to prevent o'ring extrusion. Leakage problems often arise due t lack of initial squeeze, of the o'ring diameter section being too large for its housing.

O'rings are usually used for pressures below 100 bars. If there are higher, using an back-up is recommended.

General materials:
Nitrile (NBR)- recommended for food-processing applications.
Chloroprene (CR) - recommended for many media, such as mineral lubricating oil and greases, dilute acids and alkalis and some solvents.
Natural rubber (NR) - suitable for using in hot or cold water , ammonia, ethylene glycol, dilute acids and alkalis. It have high strength and high resilience, with good abrasion resistance. Limited resistance to heat, weathering and oils has reduced the ue of natural rubber in favour of synthetic elastomers.
Ethylene - propylene (EPM/EPDM) - are ideal materials for steam raising plant. These compounds have excellent resistance to weathering, ozone, hot and cold water and steam and also to aliphatic phosphate - ester, hydraulic fluids, acids, alkalis, salt solutions, alcohols, glycols and silicone oils.
Butyl (IIR) - rubber has similar chemical resistance to ethylene-propylene. Very low gas permeability makes butyl popular for vacuum and high pressure gas applications. It must not be used with mineral oils.
Epichlorhydrin (ECO) - corrosive properties and poor compression set resistance limit the use of these materials for sealing applications. Compounds based on this elastomer have good resistance to mineral oils, fuels and ozone.
Chlorosulphonated polyethilene (CSM) - these elastomers show excellent resistance to weathering and give good service in many media. They are not recommended for dynamic seal applications as compression set resistance is limited.
Polyurethane (AU/EU) - good resistance to weathering and oxygen, and good resistance to hydrocarbon fuels and mineral oils. Resistance to acids is low, and some grades are affected by water and humidity.
Fluorosilicone (FVMQ) - recommended for applications involving hydrocarbon oils, petroleum fuels and mineral based hydraulic fluids. Primarily used for static seals in aerospace fuel systems at temperatures up to + 180 oC, this material experience similar mechanical limitations to silicone.
Silicone (VMQ) - offer good resistance to heat, weathering and compression set at high temperatures together with excellent electrical properties. High gas permeability, low tensile strength and poor resistance to tear and abrasion limit use. Some grades are suitable for food applications.

SC SUSZI SRL can supply o'rings for any application, o'ring kits standard or at customer request.