ISO 6621-4:1988

Internal combustion engines — Piston rings — Part 4: General specifications

This part lays down the general characteristics of piston rings, individual dimensional criteria of which are specified as appropriate in the ISO publications cited in clause 0. Provides a system for coding, designation and marking of the piston rings. Applies to all rings up to and including 200 mm diameter covered by the above classification for both reciprocating internal combustion piston engines and compressors.