Abstract
In sealing process rubber seals are compressed. The seal stores energy and the material press back against the sealed metal parts. Due to various factors the pressure developed by the seal on the metal parts decrease in time. The usual compression set test gives few information about the evolution in time of the sealing force. In order to obtain information about sealing capacity it was necessary to develop a new test method able to show the compression stress relaxation. For this method various devices can be used. This paper describe a device used to determine the compression stress relaxation