Overview
ISO 14456:2024 - Gas cylinders - Gas properties and associated classification (FTSC) codes defines a systematic method for classifying gases and pressurized liquids in cylinders using a four‑digit FTSC code. FTSC stands for Fire potential (oxidizing power and flammability), Toxicity, State (physical state in the cylinder at 15 °C), and Corrosiveness. The standard assigns gases and mixtures to one of 15 compatible gas groups to support safe cylinder valve selection, transport, storage and handling.
Key topics and technical requirements
- Four‑digit FTSC code: One digit per category (F, T, S, C) based on measured or referenced properties.
- Fire potential (Category I): subdivisions include inert, supports combustion, flammable, pyrophoric, oxidizing, chemically unstable.
- Acute toxicity (Category II): subdivisions for non‑toxic through very toxic based on LC50 exposure ranges.
- State (Category III): identifies liquefied, compressed, dissolved or liquid‑withdrawal gases and pressure ranges (subdivisions 0–7).
- Corrosiveness (Category IV): non‑corrosive, acid forming, basic, halogen acid forming.
- Assignment rules for single gases and intentional mixtures: the FTSC code for mixtures is determined by the final mixture’s flammability, oxidizing power, toxicity and corrosiveness. Pyrophoric components >1% by volume classify the mixture as spontaneously flammable.
- Grouping: gases are allocated to 15 compatible groups (e.g., non‑flammable, flammable toxic, oxygen, acetylene) - groups 2, 5, 10, 11 and 14 contain single gases only.
- Purpose limitation: primary use is to group compatible gases for valve outlet assignment; the code is not a material‑compatibility assessment (ISO 11114 covers material compatibility).
- Supporting data and tables: the document includes alphabetical gas tables, group characteristics, and informative Annex A with rationale for new entries.
Practical applications and who uses it
- Gas manufacturers and suppliers: consistent classification of single gases and mixtures for packaging and labelling.
- Cylinder and valve manufacturers, and fitting designers: selection of appropriate valve outlets and outlet standards (e.g., ISO 5145 referenced).
- Transport, storage and logistics operators: grouping cylinders for safe segregation and handling.
- Safety managers, emergency responders and regulatory bodies: hazard identification, compatibility grouping and planning.
- Quality and compliance teams: ensuring alignment with global systems such as GHS and national transport regulations.
Related standards and references
- ISO 11114 (material compatibility with gases)
- ISO 10156 (flammability/oxidizing power determination)
- ISO 10298 (toxicity LC50 data)
- ISO 13338 (corrosiveness criteria)
- ISO 5145 (valve outlet connections)
ISO 14456:2024 integrates these references to provide a practical, standardized approach for gas classification and cylinder valve assignment.
