Limits of use of the O-rings
Factors that can affect the performance of O-rings or decrease their efficiency are working temperatures and operating pressures.
All elastomers are characterized by a point of brittleness, and at low temperatures they lose their elastic springback characteristics. Even at high temperatures elastomers tend to harden, losing elasticity or they decrease their hardness by becoming sticky and resulting in a loss of their springback.
It is recommended to choose the working point within these limits considering a margin of 20°C: for example, if you need an o-ring that works at -20°C, you should make sure that the elastomer you choose has a brittleness point below -40°C. Similarly, if the working temperature is 100°C it will be necessary to choose an o-ring that easily withstands 120°C.
It is important to keep in mind, however, that high temperature resistance is always affected by the fluid with which the o-ring is in contact, so an elastomer can work excellently at 130°C in oil but cannot work at the same temperature in water vapor.
The durability of an o-ring is significantly affected by the steady-state temperature (average working temperatures over time) at which it is works: for example, if the o-ring is continuously subjected to a temperature of 60°C and with a few peaks of 120°C, its life may even be unlimited. However, if the same o-ring is constantly subjected to a temperature of 120°C and only rarely reaches 60°C, its life may be limited to 100-200 hours if you do not choose an o-ring that can withstand higher temperatures.
Our technical department will be able to help you choosing the right type of elastomer for your needs.
The pressure of the fluid with which the o-ring works plays a fundamental role in the life of the seal: if the pressure that the fluid exerts on the o-ring is excessively high, there is an extrusion phenomenon that can damage it irreparably due to the infiltration of the o-ring between the surfaces of the seats.
To eliminate the extrusion phenomenon, it is important to minimize the clearance between the sealing surfaces, especially in dynamic applications.