Changes of ISO/IEC 80079-49 against ISO 16852

Changes of ISO/IEC 80079-49:2024 with respect to the ISO 16852:2016 (withdrawn)

Scope of the new standard

The scope has not changed and remains for flame arresters preventing flame transmission in explosive gas-air or vapour-air mixtures, and excludes certain cases (e.g., mixtures that self-decompose, carbon disulphide, mixtures other than gas/air or vapour/air) as in the previous standard.

Significant technical changes

adaptation of the relevant IEC TC 31 requirements on standards: The new standard incorporates relevant editorial/structural requirements from IEC Technical Committee 31 (“IEC TC 31”) in how the standard is structured and referenced.
Upper temperature limit increased: The upper limit of the temperature range was raised from +150 °C (in ISO 16852:2016) to +200 °C, under the condition that the ambient temperature T₀ shall not be more than 80% of the auto-ignition temperature of the gas-air mixture. In fact, the new standard covers pressures from 80 kPa to 160 kPa and temperatures range from –20 °C to +200 °C, which reflects the above-mentioned extended upper limit.
Terminology change: “explosion group” → “equipment group”: The term “explosion group” in the previous standard has been replaced by “equipment group” in ISO/IEC 80079-49:2024, reflecting editorial requirements of IEC/TC 31.

Since the new standard is an international standard jointly by ISO/IEC under the “Explosive atmospheres” series and for the purpose of adaptation of IEC TC 31 requirements, alignment with IEC and harmonisation has been emphasised.

Clarification of conditions for non-standard atmospheric operating conditions: The new standard clarifies the conditions and requirements for flame arresters whose intended operating conditions are outside atmospheric conditions defined in Clauses 7.3.4 and 7.3.5.
Clarification of “information for use” requirements (Clause 12 f) concerning burn time: The section on user information/instructions (Clause 12(f)) now contains clarified requirements concerning burn time of flame arresters.
Addition of permission to replace visual inspection with a flow test: In the construction requirements (Clauses 7.1 and 14.1) the standard now permits replacing a visual inspection by performing a flow test.
Addition of Annex D including Flow chart for evaluation of test results: A new Annex D has been added which provides a flow chart for the evaluation of test results.

Implications of the changes

Manufacturers/users of flame arresters will need to check whether
- their equipment is covered up to +200 °C now; and
- whether the “T₀ ≤ 80 % auto-ignition temperature” condition is met.
For the purpose of reflecting the clarified burn-time requirement, "equipment documents, instructions or information for use, may need to be revised.
Updates in marking, labeling, documentation of equioment may be required regarding the change from “explosion group” to “equipment group”.
The allowance to substitute a visual inspection with a flow test offers flexibility for conformity assessment and/or maintenance practices.
The inclusion of a flow-chart in Annex D assists the manufacturers, laboratories and inspectors to evaluate test results consistently.

Detail description of the changes

Clause 1 — Scope

2024: Scope retains same subject (flame arresters) but updates the applicable temperature range to −20 °C to +200 °C and states applicability for pressures 80 kPa to 160 kPa; includes notes pointing to Annex E for operational conditions inside scope but outside “atmospheric” conditions.
Change vs 2016: 2016 specified −20 °C to +150 °C. 2024 raises the upper limit to 200 °C and adds the T₀ ≤ 80 % of auto-ignition condition (elsewhere in text).

Clause 2 — Normative references

2024: Updated to reference IEC/ISO documents aligned with IEC/TC-31 editorial structure (IEC 60079-0 etc.). Some referenced documents updated; editorial alignment with IEC directive noted.
Change vs 2016: Primarily editorial updates to normative refs and alignment to IEC/TC practices.

Clause 3 — Terms and definitions

2024: Terms reference IEC 60079-0 definitions; “equipment group” used rather than “explosion group”; definitions expanded/clarified for e.g., “stabilized burning”, “short time burning”.
Change vs 2016: Terminology update (explosion group → equipment group) and some clarifications/rewrites of definitions.

Clause 4 — Classification / Clause 5 — General requirements

2024: Classification tables (gas groups/equipment groups) preserved but sub-division of groups reiterated (IIA → IIA1/IIA, IIB → IIB1/IIB2/IIB3/IIB). Test classification tables updated to reflect 2024 test ranges.
Change vs 2016: Mostly editorial and rephrasing to adopt IEC style; tables updated where needed (see Table 1/Table 2 in 2024).

Clause 6 — Basic construction, materials & production testing

2024: Construction requirements remain but 7.1 (construction for prototype arresters) and related clauses now explicitly allow substitution of a visual inspection by a flow test in certain cases (this permission is new wording). Production test details updated for welded/cast components, flow measurement guidance remains.
Change vs 2016: New allowance to replace visual inspection with flow test; minor editorial changes and clarifications to production testing.

Clause 7 — Specific requirements for static flame arresters (and subclauses 7.1–7.5)

2024: Clause 7 expanded/renumbered in places; 7.3 Flame transmission tests contains the test matrices and the endurance burning test (7.3.5) with clarified conditions for atmospheric vs non-atmospheric operation (see Annex E cross-reference). Tables with gas mixtures and test parameters updated.
Change vs 2016: Test conditions mostly retained, but clarifications on test conditions for non-standard atmospheres, updated test parameter tables, and editorial updates. The endurance burning test and short-time burning test requirements clarified.

Clause 8 — Liquid product detonation flame arresters

2024: Requirements for liquid seals, foot valves, and flame transmission testing preserved; some test apparatus figures and detailed procedural clarifications updated.
Change vs 2016: Revisions to flame transmission test method for liquid product detonation arresters (editorial/technical clarifications).

Clause 9 — Dynamic flame arresters (high-velocity vent valves)

2024: Clause 9 kept with updates to the flame transmission test sequences, endurance burning conditions and short-time tests; additional procedural clarifications (e.g., for opening/closing tests, deflagration tests).
Change vs 2016: Clause reworded and clarified compared with 2016 (2016 had revised Clause 9 already vs the 2008 edition; 2024 continues to refine test procedures).

Clause 10 — Hydraulic flame arresters

2024: Test apparatus and procedures updated (see Figure References and Annex E for special conditions).
Change vs 2016: Clarifications and updated figures/procedures; limits for use formatted/updated.

Clause 11 — Test of flame arresters installed on/within gas-conveying equipment

2024: Retained and expanded; Tables 8/9 in 2024 give detailed numbers of individual tests and parameters for different inlet pressures (≤ 600 hPa and > 600 hPa).
Change vs 2016: 2016 added Clause 11; 2024 refines the test matrices and provides additional tabulated guidance.

Clause 12 — Information for use (instructions, burn rating, marking)

2024: Clarified requirements for information to be supplied with the flame arrester (Clause 12(f) explicitly clarifies burn time information and marking examples — see Figures and sample marking plate references).
Change vs 2016: 2016 revised instructions and marking already; 2024 further clarifies the burn time requirement and recommended statement format.

Clause 13 — Tests (general) / Clause 14 — Production testing & conformity

2024: Production testing retains earlier tests; 14.1 now includes the permission to replace a visual inspection with a flow test where appropriate — this is explicitly called out in the 2024 edition.
Change vs 2016: Permission to substitute flow test for visual inspection is the notable new allowance.

Annex A / B / C / (D & E & F) — Informative annexes

2024:
- New Annex D: Flow chart(s) for evaluation/decision process for test results (stable and unstable detonation arrester decision flows).
- Annex E: Guidance for operating conditions outside atmospheric assumptions (cross-referenced from Clauses 1 and 7).
- Annex F (or a similar annex in the published PDF): table of significant changes vs EN ISO 16852:2016 (this annex helps users see the delta).
Change vs 2016: Addition of Annex D (flow charts) and clearer Annex E guidance for non-standard atmospheres; Annex F summarizes changes.

Changes of ISO/IEC 80079-49 against ISO 16852

Changes of ISO/IEC 80079-49 against ISO 16852

Changes of ISO/IEC 80079-49:2024 with respect to the ISO 16852:2016 (withdrawn)

Scope of the new standard

The scope has not changed and remains for flame arresters preventing flame transmission in explosive gas-air or vapour-air mixtures, and excludes certain cases (e.g., mixtures that self-decompose, carbon disulphide, mixtures other than gas/air or vapour/air) as in the previous standard.

Significant technical changes

adaptation of the relevant IEC TC 31 requirements on standards: The new standard incorporates relevant editorial/structural requirements from IEC Technical Committee 31 (“IEC TC 31”) in how the standard is structured and referenced.

Terminology change: “explosion group” → “equipment group”: The term “explosion group” in the previous standard has been replaced by “equipment group” in ISO/IEC 80079-49:2024, reflecting editorial requirements of IEC/TC 31.

Since the new standard is an international standard jointly by ISO/IEC under the “Explosive atmospheres” series and for the purpose of adaptation of IEC TC 31 requirements, alignment with IEC and harmonisation has been emphasised.

Clarification of conditions for non-standard atmospheric operating conditions: The new standard clarifies the conditions and requirements for flame arresters whose intended operating conditions are outside atmospheric conditions defined in Clauses 7.3.4 and 7.3.5.

Clarification of “information for use” requirements (Clause 12 f) concerning burn time: The section on user information/instructions (Clause 12(f)) now contains clarified requirements concerning burn time of flame arresters.

Addition of permission to replace visual inspection with a flow test: In the construction requirements (Clauses 7.1 and 14.1) the standard now permits replacing a visual inspection by performing a flow test.

Addition of Annex D including Flow chart for evaluation of test results: A new Annex D has been added which provides a flow chart for the evaluation of test results.

Implications of the changes

Manufacturers/users of flame arresters will need to check whether

their equipment is covered up to +200 °C now; and

whether the “T₀ ≤ 80 % auto-ignition temperature” condition is met.

For the purpose of reflecting the clarified burn-time requirement, "equipment documents, instructions or information for use, may need to be revised.

Updates in marking, labeling, documentation of equioment may be required regarding the change from “explosion group” to “equipment group”.

The allowance to substitute a visual inspection with a flow test offers flexibility for conformity assessment and/or maintenance practices.

The inclusion of a flow-chart in Annex D assists the manufacturers, laboratories and inspectors to evaluate test results consistently.

Detail description of the changes

Clause 1 — Scope

2024: Scope retains same subject (flame arresters) but updates the applicable temperature range to −20 °C to +200 °C and states applicability for pressures 80 kPa to 160 kPa; includes notes pointing to Annex E for operational conditions inside scope but outside “atmospheric” conditions.

Change vs 2016: 2016 specified −20 °C to +150 °C. 2024 raises the upper limit to 200 °C and adds the T₀ ≤ 80 % of auto-ignition condition (elsewhere in text).

Clause 2 — Normative references

2024: Updated to reference IEC/ISO documents aligned with IEC/TC-31 editorial structure (IEC 60079-0 etc.). Some referenced documents updated; editorial alignment with IEC directive noted.

Change vs 2016: Primarily editorial updates to normative refs and alignment to IEC/TC practices.

Clause 3 — Terms and definitions

2024: Terms reference IEC 60079-0 definitions; “equipment group” used rather than “explosion group”; definitions expanded/clarified for e.g., “stabilized burning”, “short time burning”.

Change vs 2016: Terminology update (explosion group → equipment group) and some clarifications/rewrites of definitions.

Clause 4 — Classification / Clause 5 — General requirements

2024: Classification tables (gas groups/equipment groups) preserved but sub-division of groups reiterated (IIA → IIA1/IIA, IIB → IIB1/IIB2/IIB3/IIB). Test classification tables updated to reflect 2024 test ranges.

Change vs 2016: Mostly editorial and rephrasing to adopt IEC style; tables updated where needed (see Table 1/Table 2 in 2024).

Clause 6 — Basic construction, materials & production testing

Change vs 2016: New allowance to replace visual inspection with flow test; minor editorial changes and clarifications to production testing.

Clause 7 — Specific requirements for static flame arresters (and subclauses 7.1–7.5)

2024: Clause 7 expanded/renumbered in places; 7.3 Flame transmission tests contains the test matrices and the endurance burning test (7.3.5) with clarified conditions for atmospheric vs non-atmospheric operation (see Annex E cross-reference). Tables with gas mixtures and test parameters updated.

Change vs 2016: Test conditions mostly retained, but clarifications on test conditions for non-standard atmospheres, updated test parameter tables, and editorial updates. The endurance burning test and short-time burning test requirements clarified.

Clause 8 — Liquid product detonation flame arresters

2024: Requirements for liquid seals, foot valves, and flame transmission testing preserved; some test apparatus figures and detailed procedural clarifications updated.

Change vs 2016: Revisions to flame transmission test method for liquid product detonation arresters (editorial/technical clarifications).

Clause 9 — Dynamic flame arresters (high-velocity vent valves)

2024: Clause 9 kept with updates to the flame transmission test sequences, endurance burning conditions and short-time tests; additional procedural clarifications (e.g., for opening/closing tests, deflagration tests).

Change vs 2016: Clause reworded and clarified compared with 2016 (2016 had revised Clause 9 already vs the 2008 edition; 2024 continues to refine test procedures).

Clause 10 — Hydraulic flame arresters

2024: Test apparatus and procedures updated (see Figure References and Annex E for special conditions).

Change vs 2016: Clarifications and updated figures/procedures; limits for use formatted/updated.

Clause 11 — Test of flame arresters installed on/within gas-conveying equipment

2024: Retained and expanded; Tables 8/9 in 2024 give detailed numbers of individual tests and parameters for different inlet pressures (≤ 600 hPa and > 600 hPa).

Change vs 2016: 2016 added Clause 11; 2024 refines the test matrices and provides additional tabulated guidance.

Clause 12 — Information for use (instructions, burn rating, marking)

2024: Clarified requirements for information to be supplied with the flame arrester (Clause 12(f) explicitly clarifies burn time information and marking examples — see Figures and sample marking plate references).

Change vs 2016: 2016 revised instructions and marking already; 2024 further clarifies the burn time requirement and recommended statement format.

Clause 13 — Tests (general) / Clause 14 — Production testing & conformity

2024: Production testing retains earlier tests; 14.1 now includes the permission to replace a visual inspection with a flow test where appropriate — this is explicitly called out in the 2024 edition.

Change vs 2016: Permission to substitute flow test for visual inspection is the notable new allowance.

Annex A / B / C / (D & E & F) — Informative annexes

2024:

New Annex D: Flow chart(s) for evaluation/decision process for test results (stable and unstable detonation arrester decision flows).

Annex E: Guidance for operating conditions outside atmospheric assumptions (cross-referenced from Clauses 1 and 7).

Annex F (or a similar annex in the published PDF): table of significant changes vs EN ISO 16852:2016 (this annex helps users see the delta).

Change vs 2016: Addition of Annex D (flow charts) and clearer Annex E guidance for non-standard atmospheres; Annex F summarizes changes.

Download the conformity assessment checklist for ISO/IEC 80079-49:2024