scope:

This specification defines the requirements for toroidal sealing rings ('O' rings) manufactured from materials which have been approved to DTD 5597-"Vulcanized Ethylene-Propylene Rubbers (Fluid Resistant)".

They may be used in reciprocating mechanisms or for static purposes in contact with phosphate ester hydraulic liquids within a temperature range of -60° C to 100° C for continuous operation or 130° for short intermittent periods, and with silicone hydraulic liquids within the temperature range -60° C to 130° C for continuous operation or up to 160° C for intermittent periods. For application in contact with air they may also be considered for use within the temperature range -60° C to 120° C. They have excellent ozone resistance. They are unsuitable for use in contact with fuels, mineral oils, di-ester oils and silicate liquids, or greases derived from any of these.

NOTE. At ordinary temperatures and in the absence of hostile environments, e.g. when properly stored, these rubbers deteriorate only very slowly. However, the rate of deterioration increases markedly with increased temperature and the service life of a rubber therefore depends upon the operational temperature. Conversely, the maximum temperature at which a rubber may be used depends upon the useful life required.