ISO 22252:2020

INTERNATIONAL ISO
STANDARD 22252
First edition
2020-01
Manned submersibles — Breathing air
supply and CO2 adsorption systems
— Performance requirements and
recommendations
Reference number
ISO 22252:2020(E)
©
ISO 2020

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ISO 22252:2020(E)

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© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ISO 22252:2020(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General requirements and recommendations . 2
5 Material requirements and recommendations . 3
6 Breathing air supply system requirements and recommendations .3
6.1 Breathing air management . 3
6.2 Oxygen supply. 4
6.3 Breathing air supply system design . 4
6.4 Breathing air capacity . 4
6.5 Breathing air cylinder . 4
6.6 Breathing air supply pipework . 5
7 CO absorption system requirements and recommendations . 6
2
7.1 CO management. 6
2
7.2 CO absorption system design . 6
2
7.3 CO absorbents . 7
2
7.4 CO absorbents capacity . 7
2
Bibliography . 8
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ISO 22252:2020(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology,
Subcommittee SC 13, Marine technology.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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INTERNATIONAL STANDARD ISO 22252:2020(E)
Manned submersibles — Breathing air supply and CO2
adsorption systems — Performance requirements and
recommendations
1 Scope
This document specifies performance requirements and gives recommendations for the design of
breathing air supply and CO absorption systems of manned submersibles, capable of maintaining
2
suitable life support conditions in the manned compartments.
It is applicable to manned submersibles where the internal pressure of the manned compartment is
normally maintained at or near to one atmosphere.
It is not applicable to submersibles where the occupants endure pressures higher than one atmosphere
(such as in diving bells, for example).
It is not applicable to submersibles designed to carry passengers or divers in a separate compartment
capable of being pressurised to higher than one atmosphere inside the pressure hull (such as in
submarine rescue compartments, for example).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
diving bell
manned non-self-propelled submersible tethered unit consisting of at least one chamber internally
pressurized in order to allow a diver to be transported to and from an underwater site
3.2
manned submersible
craft capable of carrying personnel and/or passengers (3.6) while operating underwater, submerging,
surfacing and remaining afloat with the internal pressure of the manned compartment (3.4) normally
maintained at or near to one atmosphere
3.3
pressure hull
hull of a submersible that maintains structural integrity while under differential pressure
3.4
manned compartment
compartment of the pressure hull (3.3) in which people are carried, generally maintained at a pressure
of one atmosphere
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ISO 22252:2020(E)

3.5
passenger submersible
submersible carrying passengers (3.6) that primarily operates underwater and relies on surface
support, such as a surface ship or shore-based facilities, for monitoring and for one or more of the
following: recharging power supply, recharging high pressure air and recharging life-support
3.6
passenger
person other than the pilot and the members of the crew or other persons employed in any capacity on
board a passenger submersible (3.5) craft on the business of the craft
3.7
breathing air supply system
equipment providing breathing air to the manned compartment(s) (3.4) while the submersible is
surfaced or submerged
3.8
reserve breathing air supply system
breathing air supply equipment specifically designated as the ‘reserve’ component, that is not normally
used during planned dives unless some unforeseen emergency circumstance occurs
3.9
emergency breathing air supply system
equipment providing an independent emergency air supply for use in case of fire, smoke or other toxic
contaminants in manned compartment(s) or failure of the normal and the reserve breathing air supply
system (3.8)
3.10
CO absorption system
2
equipment providing CO absorption while the submersible is surfaced or submerged
2
3.11
LiOH
lithium hydroxide
highly alkaline inorganic compound that can absorb CO in the air
2
4 General requirements and recommendations
4.1 The breathing air supply system shall be designed with redundancies to avoid loss of breathing air
supply due to a single failure in the system.
4.2 The CO absorption system shall be designed with redundancies to avoid loss of CO removal
2 2
capability due to a single failure in the system.
4.3 The breathing air supply and CO absorption systems should be designed so that as far as
2
reasonably practicable, incorrect operation of the equipment by trained personnel is not possible.
4.4 The breathing air supply and CO absorption systems shall be fit for purpose to operate safely in
2
the specified operating parameters of the submersible. This shall be as a result of a design specification
configured to the required safe operating envelope.
4.5 The electronic equipment and systems associated with breathing air supply and CO absorption
2
systems shall be able to adapt to the electromagnetic environment of the submersible. Anti-
electromagnetic interference measures can be considered if necessary, for example, resisting interference
from the VHF.
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ISO 22252:2020(E)

4.6 The appropriate risk analysis should be used in the design of the breathing air supply and CO
2
absorption systems, which can refer to IEC 60812 or equivalent standards.
5 Material requirements and recommendations
5.1 Materials containing beryllium, asbestos and mercury shall not be used in the breathing air supply
system and in the CO absorption system.
2
5.2 The material used in the manufacture of pipework in the breathing air supply system should be
suitable for the gas in the pipework.
5.3 The metal materials used in breathing air pipework should be nickel-copper alloy (Monel), 304 or
316 stainless steel, copper, aluminum bronze (except those alloys subject to dealuminification), copper
nickel, brass (except those alloys subject to dezincification), or C-69100 copper alloy. Aluminum may only
be used when adequate precautions are taken to prevent contact with fluorochlorocarbon lubricants and
hydroxide based CO absorbents.
2
5.4 Other suitable materials may be considered on a case-by-case basis after evaluation of their
material specifications.
5.5 The following materials shall not be used for the breathing air supply pipework:
a) carbon steel,
b) cast, ductile and malleable iron piping, tubing and fittings,
c) plating or coatings with cadmium.
5.6 Pipework exposed to seawater shall be manufactured from material resistant to seawater
corrosion.
5.7 Soft goods (non-metallic materials such as gaskets, O-rings, valve seats, etc.) used in the breathing
air supply pipework shall be compatible with the gas in the pipe.
5.8 If lubricant or sealant is used in breathing system pipework, it shall be compatible with the gas
in the pipe. If the gas has an oxygen concentration exceeding 25 %, the lubricant or sealant shall be
compatible with oxygen at the maximum system supply pressure and flow rate.
5.9 If PTFE tape type thread sealant is used in threaded joints in the breathing air supply pipework, it
shall be demonstrated that all potential hazards associated with the disintegration/shredding of the tape
have been addressed.
5.10 Valve parts in the breathing air supply pipework shall meet the material requirements of 5.1 to 5.9.
5.11 The manufacturing materials of the CO absorption system shall be corrosion-resistant and non-
2
toxic, and the materials shall be compatible for use with CO absorbent chemicals.
2
6 Breathing air supply system requirements and recommendations
6.1 Breathing air management
a) The oxygen concentration in the manned compartment should be kept between 18 % and 23 %
by volume.
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