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 −73°C (−100°F)). Class 1 material also possesses resistance to extreme high temperature (to approximately 219°C (425°F)), 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 219°C (425°F). Class 2 material possesses low temperature resistance, but only to about −62°C (−80°F). Class 2B material also possesses low compression set. Class 3A - Where resistance to extreme low temperature (to approximately −75°C (−103°F)), and resistance to tearing and flexing are required. Class 3A material also possesses resistance to extreme high temperature, to approximately 204°C (400°F). 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 −70°C (−94°F) and 204°C (400°F).