The use temperature is another important factor affecti […]
The use temperature is another important factor affecting the permanent deformation of the O-ring. High temperatures accelerate the aging of rubber materials. The higher the operating temperature, the greater the compression set of the O-ring. When the permanent deformation is greater than 40%, the O-ring loses its sealing ability and leaks. The initial stress value formed in the rubber material of the O-ring due to compression deformation will gradually decrease and disappear as the O-ring relaxation process and temperature decrease. An O-ring whose temperature is operating at zero may have an initial compression that may decrease or disappear completely due to a sharp drop in temperature. In the case of -50 to -60 ° C, the low temperature resistant rubber material will completely lose the initial stress; even if the low temperature resistant rubber material, the initial stress at this time will not be greater than 25% of the initial stress at 20 ° C. This is because the initial compression of the O-ring depends on the coefficient of linear expansion. Therefore, when the initial compression amount is selected, it is necessary to ensure sufficient sealing ability after the stress drop due to the relaxation process and temperature drop.
For O-rings whose temperature is below zero, special attention should be paid to the recovery index and deformation index of the rubber material.
In summary, the design should ensure that the O ring has a suitable working temperature, or use high-temperature, low-temperature O-ring materials to extend the service life.