Manned submersibles -- Breathing air supply and CO2 adsorption systems -- Performance requirements and recommendations

This document specifies performance requirements and gives recommendations for the design of breathing air supply and CO2 absorption systems of manned submersibles, capable of maintaining 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).

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Status
Published
Publication Date
14-Jan-2020
Current Stage
6060 - International Standard published
Start Date
09-Jan-2020
Completion Date
15-Jan-2020
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ISO 22252:2020 - Manned submersibles -- Breathing air supply and CO2 adsorption systems -- Performance requirements and recommendations
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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)
COPYRIGHT PROTECTED DOCUMENT
© 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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Published in Switzerland
ii © ISO 2020 – All rights reserved
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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

7.1 CO management................................................................................................................................................................................... 6

7.2 CO absorption system design ................................................................................................................................................... 6

7.3 CO absorbents ....................................................................................................................................................................................... 7

7.4 CO absorbents capacity ................................................................................................................................................................. 7

Bibliography ................................................................................................................................................................................................................................ 8

© ISO 2020 – All rights reserved iii
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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

through ISO technical committees. Each member body interested in a subject for which a technical

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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

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

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expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

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.
iv © ISO 2020 – All rights reserved
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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

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
equipment providing CO absorption while the submersible is surfaced or submerged
3.11
LiOH
lithium hydroxide
highly alkaline inorganic compound that can absorb CO in the air
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

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

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

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

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.

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.

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-

toxic, and the materials shall be compatible for use with CO absorbent chemicals.

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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