ISO 6621-1:2018 defines the most commonly used terms for piston rings. These terms designate either types of piston rings or certain characteristics and phenomena of piston rings.

The terms and definitions in this document apply to piston rings for reciprocating internal combustion engines. They may also be used for piston rings of compressors working under analogous conditions.

NOTE 1 Further terms and definitions covering measuring principles are given in ISO 6621-2:2003.

NOTE 2 This document gives the equivalent terms in the Chinese, English, French, German, Italian, Japanese, Portuguese, Russian and Spanish language.