This document specifies the requirements for flame arresters that prevent flame transmission when explosive gas-air or vapour-air mixtures are present. It establishes uniform principles for the classification, basic construction and information for use, including the marking of flame arresters, and specifies test methods to verify the safety requirements and determine safe limits of use. This document is applicable to pressures ranging from 80 kPa to 160 kPa and temperatures ranging from -20 °C to +200 °C. This document does not apply to the following: - external safety-related measurement and control equipment that might be required to keep the operational conditions within the established safe limits; - flame arresters used for explosive mixtures of vapours and gases, which tend to self-decompose (for example, acetylene) or which are chemically unstable; - flame arresters used for carbon disulfide, due to its special properties; - flame arresters whose intended use is for mixtures other than gas-air or vapour-air mixtures (for example, higher oxygen-nitrogen ratio, chlorine as oxidant); - flame arrester test procedures for reciprocating internal combustion engines; - fast acting valves, extinguishing systems and other explosion isolating systems; - Flame arresters used in gas detectors (those being covered for example, by IEC 60079‑29‑1 and IEC 62990‑1). This edition cancels and replaces ISO 16852:2016, which has been technically revised. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to ISO 16852:2016: a) adaptation of the relevant IEC TC 31 requirements on standards; b) modification of the upper limit of the temperature range from 150 °C to 200 °C under the condition that T0 shall be not larger than 80 % of the auto ignition temperature of the gas-air-mixture; c) change of the term "explosion group" to "equipment group" due to editorial requirements in IEC/TC 31; d) clarification of the conditions and requirements for flame arresters whose intended operating conditions are outside the atmospheric conditions in 7.3.4 and 7.3.5; e) clarification of the requirements on the information for use in Clause 12 f) concerning the burn time; f) addition of a permission to the construction requirements both in 7.1 and 14.1 to substitute visual inspection by performing a flow test; g) addition of a flow chart for the evaluation of test results as Annex D