A-A-59588
The silicone rubber shall be of the following classes and grades, as specified:
Class 1A – Low temperature resistant.
Grades – 40, 50, 60, 70, 80
Class 1B – Low temperature resistant and low compression set at high temperature.
Grades – 40, 50, 60, 70, 80
Class 2A – High temperature resistant.
Grades – 25, 40, 50, 60, 70, 80
Class 2B – High temperature resistant and low compression set.
Grades – 25, 40, 50, 60, 70, 80
Class 3A – Low temperature, tear and flex resistant.
Grades – 30, 50, 60
Class 3B – Tear and flex resistant.
Grades – 30, 50, 60, 70, 80
The silicone rubber covered by this specification is intended generally for use under the conditions listed below. Users should, however, consider all the requirements of this specification when selecting a class and grade of silicone rubber.
Class 1 – Where resistance to extreme low temperature is required to approximately -73ºC (-100ºF). Class 1 material also possesses resistance to extreme high temperature (to approximately 219ºC (425ºF)), but length of service at high temperatures is less than that of the class 2 materials. The class 1B material also possesses low compression set at high temperature.
Class 2 – Where resistance to extreme high temperature is required to approximately 219ºC (425ºF). Class 2 material possesses low temperature resistance, but only to about -62ºC (-80ºF). Class 2B material also possesses low compression set.
Class 3A – Where resistance to extreme low temperature to approximately -75ºC (-103ºF), and resistance to tearing and flexing are required. Class 3A material also possesses resistance to extreme high temperature to approximately 204ºC (400ºF).
Class 3B – Where resistance to tearing and flexing are required, but the resistance to extreme low temperature requirement is less than that of the class 3A material. Temperature range for the class 3B material is approximately between -70ºC (-94ºF) and 204ºC (400ºF).