Overview
EN ISO 11621:2005 (adopting ISO 11621:1997) specifies procedures for changing the gas service of refillable gas cylinders. It applies to seamless steel, aluminium-alloy and welded steel cylinders of all sizes (including large cylinders with water capacity >150 L). The standard gives general requirements and stepwise actions to follow when transferring cylinders between services for permanent and liquefied gases. It does not apply to cylinders for dissolved acetylene, radioactive gases or gases listed in group G of the standard’s gas classification.
Keywords: EN ISO 11621:2005, gas cylinders, change of gas service, cylinder transfer procedures, ISO 11621:1997.
Key topics and requirements
- Scope and exclusions: Defines cylinder types and services covered; excludes certain hazardous gases and special cases.
- Gas grouping and compatibility: Gases are grouped (e.g., inert, oxidizing, flammable, embrittling, carbon monoxide, toxic) to determine required actions for each transfer. Compatibility with cylinder and valve materials must be checked (see ISO 11114-1).
- Stepwise actions: The standard lists numbered actions (steps 1–10) such as:
- External examination and preparation (identification, surface/valve check, labels, ownership, test date)
- Check for moisture and hydrocarbons, internal visual inspection
- Material compatibility verification
- Check for internal corrosion or surface defects
- Cylinder evacuation, purging or vacuum (where appropriate)
- Non‑destructive testing (NDT) and hydrostatic testing when exposure to water or incompatible service is suspected
- Cleaning and purging: Emphasizes removing residual gas, contaminants and cleaning agents, then drying and sealing cylinders to prevent recontamination.
- Valve and safety device checks: Verify valve outlet types (ISO 5145 or national equivalents), pressure relief devices and operational condition.
Keywords: cylinder inspection, purging, cleaning, valve compatibility, NDT, hydrotest.
Practical applications and users
- Gas suppliers and filling plants - safe reassigning of returned cylinders to different gases.
- Cylinder refurbishment and requalification facilities - inspection, cleaning, NDT and re‑testing workflows.
- Industrial gas distributors, laboratories and medical gas suppliers - ensure contaminant‑free supply and regulatory compliance.
- Safety officers, inspectors and regulatory bodies - define required checks and recordkeeping when changing gas service.
Keywords: gas suppliers, cylinder refurbishment, industrial gas safety, transportable gas cylinders.
Related standards
- ISO 11114-1 - compatibility of cylinder/valve materials with gases
- ISO 5145 - cylinder valve outlet selection and dimensioning
- ISO 6406, ISO 10460, ISO 10461 - periodic inspection and testing of gas cylinders
- ISO 10156 - fire potential/oxidizing ability for valve selection
- Superseded: EN 1795:1997
For implementation, consult the full EN ISO 11621:2005 text and the referenced standards to ensure compliance with material compatibility, inspection intervals and national regulations.
