The materials covered by this specification are intended mainly for the manufacture of seals which are normally required to operate at temperatures up to +225"C in contact with air, petroleum-based and diester-based fluids where low compression set is of primary importance. For static applications, the materials may be suitable for use at temperatures down to -50°C, but with increasing frequency/amplitude the low temperature behaviour will deteriorate and they may not be suitable below -20°C.

In certain applications, the materials may be suitable in contact with silicone and silicate ester fluids, but where such use is contemplated the designer should satisfy himself of the suitability of the material for the particular application.

The materials are not suitable for use with certain phosphate ester-based fluids.

NOTE. At ordinary temperatures and in the absence of hostile environments, eg when properly sfored, these rubbers deteriorate only very slowly. For most practical purposes the effect is insignijìcant and the storage life of fluoro-carbon rubbers may be considered indefinite. Howevèr, the rate of deterioration increases markedly with increased temperature and the service life of the rubber therefore depends upon the operational temperature. Conversely, the maximum temperature at which the rubber may be used depends upon the useful life required.