Overview
ISO 407:2023 - Small medical gas cylinders - Pin‑index yoke‑type valve connections - defines dimensional and safety requirements for pin‑index yoke‑type valve connections used on small medical gas cylinders (typically 5 L or below). It applies to connections for cylinders with a working pressure up to 200 bar and/or a test pressure up to 300 bar. The standard specifies basic dimensions, allowable alternative yoke designs, and exact positions and dimensions for pins and holes for outlet connections for medical gases and mixtures.
Note: ISO 407 uses the unit bar (1 bar = 10^5 Pa) because of its universal use in the gas industry, though bar is not an SI unit.
Key technical topics and requirements
- Scope and sizing: Targeted at small cylinders (≤ 5 L) and high‑pressure applications (≤ 200 bar working / 300 bar test).
- Pin‑index system: Defines single‑pin and two‑pin (single‑row and double‑row) yoke connection systems and the allocated pin positions for specific gases (e.g., O2, N2O, Air, He, CO2, ethylene, cyclopropane).
- Dimensional control: Detailed basic dimensions and tolerances for valve bodies, yokes, pins and holes (see Clause 6 and Clause 8, and Figures 1–18).
- Safety and interchange prevention:
- A gas‑tight seal must only occur when the yoke pins correspond to the valve holes.
- If pins do not match holes, a gas‑tight seal must not be possible and mechanical damage must be prevented.
- Yoke construction and performance:
- Pins must be fixed or assembled to prevent user removal or loosening.
- Only a single retained sealing washer is permitted on the yoke spigot.
- The yoke must withstand a torque of 50 N·m on the clamping screw without permanent deformation.
- Yoke dimensions must limit valve movement to a maximum of 6° about the long axis prior to pin engagement.
- Marking and identification: The gas name or chemical symbol must be indelibly stamped on both valve and yoke; color identification should comply with ISO 32 where used.
Practical applications and users
ISO 407:2023 is essential for:
- Cylinder and valve manufacturers designing pin‑index yoke valves for medical gases.
- Medical equipment suppliers and hospitals specifying safe, non‑interchangeable connections for oxygen, nitrous oxide, medical air, helium, CO2, and mixed gases.
- Regulators and testing laboratories validating conformity of small medical gas cylinders and fittings.
- Maintenance and safety engineers implementing cylinder handling, inventory and compatibility controls.
Related standards
- ISO 32 - Gas cylinders for medical use - Marking for identification of content (referenced for color/marking practices).
Keywords: ISO 407:2023, pin‑index yoke‑type valve, small medical gas cylinders, medical gas cylinder valves, yoke connection, valve pin‑hole dimensions, gas safety standard.
