Overview
EN ISO 11755:2020 (adoption of ISO 11755:2005) defines inspection requirements for gas cylinder bundles used with compressed and liquefied gases (excluding acetylene). It covers visual and functional checks to be performed before, during and after filling to ensure bundle integrity, correct filling, and safe transport/use. The standard applies to transportable assemblies (frames with two or more cylinders, each up to 150 L water capacity) commonly known as cylinder bundles.
Key topics and requirements
- Scope & exclusions
- Applies to bundles for compressed and liquefied gases; does not apply to acetylene bundles or bundles integrated into battery vehicles.
- Definitions
- Clarifies terms such as compressed gas, liquefied gas (high/low pressure by critical temperature), manifold, main outlet valve, tare weight, and maximum permissible filling weight.
- Inspection prior to filling
- Verify country approval for filling, valid periodic inspection/test date, compatibility with gas and filling pressure/weight.
- Inspect frame, restraining systems, lifting attachments, manifold, flexible hoses, valves and pressure-relief devices for damage or tampering.
- Check cylinder surfaces for dents, cuts, fire damage or signs of immersion/contamination; apply rejection criteria from ISO 6406 / ISO 10461 / ISO 11623 as appropriate.
- Ensure positive residual pressure (to detect internal contamination) and, for liquefied gases, confirm mass vs. tare weight.
- Marking and identification
- Bundles must be permanently marked with design/approval references, country code, inspection stamp, initial inspection date (YYYY/MM), test pressure (“PH…BAR”), working pressure (“PW…BAR” for compressed gases), water capacity in litres, tare weight and maximum filling weight (where applicable), manufacturer’s mark and serial number.
- Inspection during filling
- To prevent overfilling of liquefied-gas bundles with individual closable valves: either dismantle and fill one cylinder at a time, or fit each cylinder with a separate filling-control device.
- Monitor for leaks, especially with toxic, flammable or pyrophoric gases.
- Inspection after filling
- Confirm no overfill (pressure corrected for reference temperature or mass checked against permitted filling weight), verify markings/labels, ensure main outlet valve and cylinder valves do not leak and are correctly set for transport.
Applications and who uses it
- Filling station operators and cylinder filling technicians
- Gas suppliers, transport safety officers, and logistics teams handling bundles
- Inspection and certification bodies performing periodic tests
- Manufacturers and designers of cylinder bundles and manifolds
- Safety managers in industries using bulk gas supplies (industrial gases, welding, medical gases, specialty gases)
Related standards
- ISO 6406 (seamless steel cylinders - periodic inspection/testing)
- ISO 10461 (aluminium-alloy cylinders - periodic inspection/testing)
- ISO 11623 (composite cylinders - periodic inspection/testing)
- EN 13769 (design, manufacture and testing of cylinder bundles)
- UN Model Regulations on the Transport of Dangerous Goods
Keywords: EN ISO 11755:2020, gas cylinders, cylinder bundles, inspection at time of filling, compressed gases, liquefied gases, filling inspection, filling procedures.
