Overview
ISO 22252:2020 specifies performance requirements and design recommendations for breathing air supply and CO2 adsorption (absorption) systems in manned submersibles whose internal pressure is normally at or near one atmosphere. The standard focuses on maintaining safe life‑support conditions in manned compartments and defines system architecture, material selection, capacity sizing and operational safeguards. It excludes diving bells and compartments designed to operate above one atmosphere (for example submarine rescue compartments).
Key topics and technical requirements
- System architecture and redundancy
- Requires three-part breathing air arrangements: normal, reserve, and independent emergency systems.
- CO2 removal systems must also be redundant to tolerate a single failure.
- Breathing air management
- Target oxygen concentration in the manned compartment: 18–23% by volume.
- Air purity should meet recognized standards (e.g., ISO 8573-1, CGA G‑7.1) or equivalent.
- Oxygen supply & capacities
- Recommended oxygen supply rate: 28.3 L per person per hour (measured at 1 atm, 20 °C).
- Reserve system capacity: not less than breathing demand for 72 hours (consistent with rescue plans).
- Emergency system: independent supply sized to provide 150% of the normal time to reach the surface or 1 hour, whichever is greater.
- CO2 adsorption
- Design and sizing of CO2 absorbents (e.g., LiOH noted) and systems to maintain safe CO2 levels; materials must be compatible and non‑toxic.
- Materials and pipework
- Prohibits use of beryllium, asbestos, mercury in life‑support systems.
- Preferred metals for breathing air pipework include Monel, 304/316 stainless steel, copper, copper‑nickel, etc.; some materials (aluminum, certain brass/alloys) have use restrictions.
- Pipework and non‑standard valves must have a burst strength ≥ 4× MAWP; valves suitable for oxygen service and permanently marked.
- Cylinders and storage
- Cylinder standards referenced (e.g., ISO 9809 series, CGA).
- Cylinders stored inside the pressure hull must not, if fully released, increase hull pressure > 1 atm or raise O2 above 23% by volume. External cylinders should be arranged in separate banks with independent hull penetrations.
Applications and who uses it
ISO 22252:2020 is intended for:
- Submersible designers, OEMs and systems integrators specifying life‑support systems
- Marine and offshore safety engineers and naval architects
- Classification societies, regulators and procurement teams evaluating compliance
- Maintenance crews and life‑support technicians developing inspection and emergency plans
The standard helps ensure reliable breathing air delivery and CO2 control for safe underwater operations, supports design reviews, risk assessments and rescue‑planning discussions.
Related standards
Keywords: ISO 22252:2020, manned submersibles, breathing air supply, CO2 adsorption, life support systems, oxygen supply rate, emergency breathing systems.
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