pas95-2011-specification draft - hypoxic fire prevention systems for occupied spaces-.pdf

8/14/2019 PAS95-2011-Specification Draft - Hypoxic Fire Prevention Systems for Occupied Spaces-.pdf

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PAS 95:2011

2 BSI2010

Contents

Foreword 30 Introduction 5

1 Scope 62 Terms and definitions 7

3 Use and limitations 104 System design 114.1 Planning 114.2 Provisions 114.3 System specification 124.4 Control panel 134.5 Design oxygen concentration level 134.6 Indoor air climate 144.7 Flushing 144.8 Monitoring 144.9 Data retention 145 Installation, testing and maintenance 165.1 Installation 165.2 Testing 165.3 Documentation 165.4 Operation, maintenance and servicing instructions 17AnnexesAnnex A (informative) Hypoxic fire prevention concept 18Annex B (normative) Ignition-limiting oxygen threshold testing 20Annex C (informative) System specification: graphical representations 27Annex D (informative) Health and safety: working in hypoxic environments 29Annex E (informative) Servicing 38

Bibliography 39

List of figuresFigure A.1 Hypoxic fire prevention system concept 18Figure B.1 Ignition-limiting oxygen threshold testing set-up 22Figure C.1 Example of graphical output of key design parameters, including leakage,minimum/maximum oxygen concentration level, time to reach design oxygen concentrationlevel, compressor output and duty cycle 27Figure C.2 Demonstration of hold time 27Figure D.1 Protocol for working in a class 1 hypoxic environment 34Figure D.2 Protocol for working in a class 2 hypoxic environment 34Figure D.3 Protocol for working in a class 3 hypoxic environment 35Figure D.4 Protocol for working in a class 4 hypoxic environment 36List of tablesTable B.1 Test sample exceptions 21Table D.1 Time of useful consciousness at decreasing oxygen partial pressure(unacclimatized persons) 29Table D.2 Risk classification of hypoxia and actions recommended as precautions 31Table D.3 Common topics and questions raised 33


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PAS 95:2011

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Foreword

This Publicly Available Specification (PAS) was sponsored by the following companies:AcecoTI, Colorado Altitude Training, COWI, FirePASS Europe, Hypoxic Technologies, LPGFire, Opsys, Prevenex Europe and Wagner Group all members of the Summit Air Institutefor Preservation, Health and Safety (SAIPHS). Its development was facilitated by the British

Standards Institution (BSI). It came into effect on (date of publication).

Acknowledgment is given to the following organizations that were involved in thedevelopment of this PAS as members of the Steering Group:

COWI

FirePASS Europe

Gotland University

LPG Fire

Prevenex Europe

Smithsonian Institution The Altitude Centre

Wagner Group

This PAS is published by BSI, which retains its ownership and copyright. BSI reserves theright to withdraw or amend this PAS on receipt of authoritative advice that is appropriate todo so. This PAS will be reviewed at intervals not exceeding two years, and any amendmentsarising from the review will be published as an amended PAS and publicized in UpdateStandards.

This PAS is not to be regarded as British Standard. It will be withdrawn upon publication ofits content in, or as, a British Standard.

The PAS process enables a specification to be rapidly developed in order to fulfil animmediate need in industry. A PAS must be considered for further development as BritishStandard, or constitute part of the UK input into the development of a European orInternational Standard.

Information about this document

Product certification. Users of this PAS are advised to consider the desirability of third-partycertification of product conformity with this PAS. Users seeking assistance in identifyingappropriate assessment bodies or schemes may ask BSI to forward their enquiries to therelevant association, or contact SAIPHS at [email protected].

Use of this document

It has been assumed in the preparation of this PAS that the execution of its provisions will beentrusted to appropriately qualified and experienced people, for whose use it has beenproduced.

Presentation conventions

The provisions of this PAS are presented in roman type. Its requirements are expressed insentences in which the principal auxiliary verb is "shall". Its recommendations are expressed

in sentences in which the principle verb is should.


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Commentary, recommendations, explanation and general informative material is presentedin smaller italic type, using the heading NOTE, and does not constitute a normative element.

Contractual and legal considerations

This publication does not purport to include all the necessary provisions of a contract. Usersare responsible for its correct application.

Compliance with a PAS does not confer immunity from legal obligations.


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0 Introduction

Hypoxic fire prevention systems provide a means of inhibiting the development of f lamingfires and thus preventing fires from causing significant damage. They differ fromfire-extinguishing systems in that they provide a continuous level of prevention rather than adischarge of extinguishing agent once a fire has been detected.

Normal air is a mixture of oxygen and nitrogen together with small quantities of argon,carbon dioxide and other gases. Oxygen is the critical element that supports both life andcombustion. When the oxygen content is intentionally lowered for special applications, theresulting gas is called hypoxic air or low-oxygen air.

Hypoxic fire prevention systems are applied in installations where it is possible to control theenvironment of the protected space, either exclusively for fire prevention or in combinationwith other indoor climate control (e.g. temperature or humidity). They are used, for example,in archives, vaults, computer facilities, warehousing and cold storage. Hypoxic fireprevention systems used in the protection of artefacts and other materials affected byoxidation (e.g. food, paper, paintings, metals) can reduce oxidative degradation.

Hypoxic air systems using similar oxygen levels are used by athletes for physical fitness,training and rehabilitation and in medical research. Fire prevention is a relatively newapplication for such systems (Annex A details the concept). This PAS specifies provisions fortheir use in occupiable spaces.


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1 Scope

This Publicly Available Specification (PAS) specifies requirements for the design, installation,testing and maintenance of hypoxic fire prevention systems in occupiable spaces.

This PAS defines the limits of use of such systems.

This PAS is not applicable for fire-extinguishing systems covered by theBS EN 15004 series.

This PAS does not specify for full fire risk assessment.


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2 Terms and definitions

For the purpose of this PAS, the following terms and definition apply.

2.1approvedacceptable to a relevant authority (see 2.2)

NOTE In determining the acceptability of installations or procedures, equipment or materials, the authoritymay base acceptance on compliance with the appropriate standards.

2.2authorityorganization, office or individual responsible for approving equipment, installations orprocedures

2.3competent persondesignated person, suitably trained and/or qualified by knowledge and practical experience

and with the necessary instructions to enable the required function to be carried out2.4control panelcomponent that receives and sends signals to other components of the system, including thebuilding management system (optional) and the fire detection alarm system (optional), withcontrol, monitoring and measurement functions, and alarm and annunciation features tomaintain the required oxygen concentration level in the protected area

2.5design oxygen concentration leveloxygen concentration in volume percentage used as the design basis for a hypoxic fireprevention system specification, determined by subtracting not less than 1% by volume

safety factor from the lowest tested ignition-limiting oxygen threshold of materials likely to befound in, or as part of the fabric of, the protected space

2.6flushingprocess during which the hypoxic air system is shut down and the air in the room is replacedwith fresh air

2.7hold timemaximum permissible period of time that the oxygen level in a protected space remains at orbelow the design oxygen concentration level after the input from the hypoxic fire preventionsystem has been disabled

2.8hypoxic airair in which the concentration of oxygen has been artificially reduced from normalconcentrations for a specific purpose

2.9hypoxic fire prevention systemsystem designed to use a hypoxic environment to prevent and/or inhibit fire

2.10hypoxic air generatorcomponent of a hypoxic fire prevention system that splits air on a molecular level to generate

a mix of oxygen, nitrogen, carbon dioxide and water


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2.11hypoxic environmentenvironment containing hypoxic air in which humans can operate at a normal level of activityfor short or extended durations (as appropriate) without the aid of specialized equipment(such as breathing apparatus)

2.12hypoxic air venting systemhypoxic air system that generates hypoxic air containing 10% or more oxygen by volume

2.13ignition-limiting oxygen thresholdoxygen concentration required for limiting ignition and preventing sustained flamingcombustion of materials when tested in accordance with specified standard procedures

NOTE See Annex B for the test method.

2.14indoor air climate (of the hypoxic fire prevention system)

operating climate, taking into account fresh air make-up (normally exclusively via the hypoxicfire prevention system), temperature and humidity

2.15inward leakageflow of ambient (non-hypoxic air) into the protected space resulting from structural leakageand additional leakage through doors/windows opening, etc.

NOTE 1 Maximum leakage is often expressed as a percentage of the volume of the protected space perhour.

NOTE 2 The test methods described in ISO 16000-8:2007 and the equivalent NT VVS 118:1997 aresuitable means of measuring leakage under non-pressurized conditions. Room integrity test methods usingpressure differential cannot be applied without a valid calculation to correct for influence of pressure.

2.16maximum oxygen concentration leveloxygen concentration in percentage by volume at or below the design oxygen concentrationlevel

2.17minimum oxygen concentration leveloxygen concentration in percentage by volume below which the oxygen level shall not go

2.18nitrogen injection systemhypoxic fire prevention system that generates air containing more than 90% nitrogen by

volume2.19occupiable spacespace intended for human occupancy

2.20operatornatural or legal person exercising actual power over the technical functioning of theequipment and systems (designated in the system logbook)

2.21oxygen alarm leveloxygen concentration level that is at the extreme of the allowable range of oxygen levelsspecified for fire prevention in the protected space


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NOTE This applies to both high and low oxygen alarm levels.

2.22oxygen-monitoring system (OMS)automatic electronic device capable of measuring the oxygen concentration level within ahypoxic environment

NOTE The OMS can be equipped with chemical, electrochemical, infrared, ultrasonic or other types ofsensors allowing reliable oxygen monitoring.

2.23protected spaceenclosed volume containing the hypoxic environment


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3 Use and limitations

The design, installation, testing and maintenance to ensure proper system function ofhypoxic fire prevention systems shall be performed by competent persons.

The hazards against which these systems offer protection, and any limitations on their use,shall be contained in the system supplier's design manual.

Unless relevant testing has been carried out to the satisfaction of the authority, inaccordance with Annex B, hypoxic fire prevention systems shall not be used in areas where:

a) explosive mixtures of gases, particulates and liquids are present;

b) reactive metals, cellulose nitrate, gun powder, metal hydrides, hydrazine and otherchemicals capable of auto-thermal decomposition are handled or stored;

c) sufficient air leakage control cannot be achieved;

d) an alternative source of oxygen is present.

Consideration shall be made of the effect of altitude on the available oxygen for respiration.

NOTE 1 A hypoxic environment cannot prevent non-oxidizing smouldering or pyrolysis.

NOTE 2 Hypoxic fire prevention systems cannot be used in conjunction with smoke control systems.


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4 System design

4.1 Planning

The following objectives shall form the basis of the planning process:a) to create a design that is effective in preventing fire;

b) to create an environment that does not pose a risk to persons.

4.2 Provisions

The design of the hypoxic fire prevention system shall include provision for:

coordination and integration with the fire safety strategy for the building and protected space;

a) integration with other systems within the building and with the building itself (e.g. firealarm, building management, ventilation, environmental);

b) where the system is integrated into an air-conditioning system utilizing remoteair-handling units (AHUs) that serve the protected space, air tightness of the ductworkand the AHUs that may comprise the leakage;

NOTE Where possible, arrangements should be made to utilize the heat generated by the process ofcompression.

c) modification of the building construction by sealing or other techniques to enableretention of the hypoxic environment so as to meet the maximum inward leakage ofexternal non-hypoxic air as specified by the system designer;

d) detection of non-oxidizing smouldering or pyrolyzing processes that can occur in thehypoxic air environment by means of an air-aspirating high-sensitivity smoke detection

system taking into account the airflows, possible ignition and restrained combustionscenarios within the protected space;

NOTE An example could be an overheating cable with pyrolysis of the plasticizer coating. A flaming firewill not develop in a correctly designed hypoxic air environment, but detection of this event is desirable tosignal and effect remedial action.

e) definition of an inward leakage specification taking into account the access requirementsof personnel, the behaviour and function of all ventilation and environment controlsystems, and any other features or systems that may impact on the retention of thehypoxic environment;

NOTE The user should be aware of the relationship between leakage, design oxygen concentration leveland system duty cycle that directly effects fire prevention and the required energy consumption to maintain

this.

f) construction of the protected space in such a way that it presents a barrier to firespreading from an adjacent (non-protected) space for a time period determined by localregulations or the building fire safety strategy;

g) functions occurring in the protected space. Where stored materials may give off odoursor gases that are undesirable, the design shall recommend flushing at recommendedintervals and may include suitable gas detection;

h) determining the design oxygen concentration level appropriate to the types of material tobe found in the protected space. All data relating to the required oxygen concentrationlevel, in conjunction with the duration of time persons will spend in the protected space

and the level of activity undertaken while there, should be made available forincorporation into the health and safety policy;


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i) types of combustible materials and their configuration in the protected space, todetermine the applicability of using an appropriate ignition-limiting oxygen threshold orthe need to conduct testing to establish a design oxygen concentration level;

NOTE Some combustibles contain variable amounts of chemically bonded oxygen, some may containnormal air in pockets (e.g. bubble wrap) and stored combustibles may be plastic wrapped. The

combustibles should be assessed by ignition-limiting oxygen threshold and behaviour in defined tests(see 4.4 and Annex B).

j) the injection method and any circulation methods applied;

k) considerations related to discarding high-oxygen by-product from the hypoxic airgenerator;

NOTE The high-oxygen by-product is usually vented to the atmosphere but could conceivably be usedfor other purposes.

l) consideration of the acoustic impact of air injection inside the protected space andcompressor noise from the hypoxic air generator;

m) management of compressor heat and condensate drainage that may be produced by the

hypoxic air generator.NOTE Where a decision is taken to exclude any of the above items, justification should be provided inthe design documentation.

4.3 System specification

The design specification for the hypoxic fire prevention system shall include:

a) the total volume of protected space, together with the number and shape (dimensions) ofrooms comprising that protected space;

b) the associated design oxygen concentration levels (maximum and minimum) to reflect

the fire prevention requirements based on the combustible contents;NOTE As an example, a hypoxic fire prevention system designed to maintain a protected space at 15.5%oxygen level (ignition-limiting oxygen threshold of 16.5%) could stop hypoxic air generation at 14.5%(minimum oxygen concentration level) and restart the generation at 15.5% (maximum oxygenconcentration level).

c) the design leakage, together with the method of assessment;

NOTE 1 An estimate can be made of the total leakage (e.g. in the case where the protected space hasyet to be constructed). The built environment can be verified by an approved test method formeasuring leakage at non-pressurized condition, as in ISO 16000-8:2007 or the equivalent NTVVS 118:1997.

NOTE 2 A method for verifying system design to compensate for leakage must be demonstrated. Thisis likely to be direct measurement of rate of oxygen reduction versus hypoxic air generator output.

d) the type and arrangement of the oxygen-monitoring system;

e) a means of verification for the oxygen-monitoring system, to ensure no loss of fireprevention or risk to personnel safety through failure of one or more oxygen sensors;

f) provision of a standby power supply to the oxygen-monitoring system for 24 hours as perBS EN 5839 Part:1 Clause 16;

g) a method to ensure adequate mixing of the environment;

h) the types, pressure ratings and sizes of distribution piping;

i) the performance output of the hypoxic air generator (i.e. flow rate and oxygenconcentration level), compressor power consumption and duty cycle;

j) the time to achieve the minimum and maximum oxygen concentration level from start-up;


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k) the duty cycle (onoff time) of the system;

l) the hold time of each protected space under power failure conditions;

m) alarms and status outputs, local and remote;

n) the types and sizes of control and sensor cables;

o) the ventilation/cooling requirements/space for the compressor system;

p) the access events and size of access opening;

NOTE This will require a knowledge of the differential pressure or linear air flow, to enable a volumetriccalculation of inward air leakage caused through each access event. This value should be added to thebackground inward leakage to give a total leakage value.

q) the system data-logging capability and communications protocol for external systems;

r) the methods employed to ensure safety of persons occupying the protected space;

s) the dimensions and weights of major components;

t) techniques to avoid unauthorized adjustment of system configured settings (e.g. oxygen

and alarm levels);

u) installation instructions and commissioning procedures for the system;

v) operational and servicing requirements (including records required).

NOTE 1 An example of how the system operation can be documented is given in Figure C.1.

NOTE 2 An example of hold time is given in Figure C.2.

4.4 Control panel

All control panel alarms shall be available to connect to a remote central supervisory centreor manned central station.

The panel shall incorporate a standard communications protocol to allow effective interfacingwith other fire and building management systems and for the collection and storage ofsystem performance data.

The control panel shall include, as a minimum:

a) the oxygen concentration level measured by each individual sensor;

b) alarm indications at oxygen alarm levels measured on any of the oxygen sensors in theprotected area;

c) a general fault status;

d) an online status with deactivation switch;

e) controls for deactivation of the system;

f) control of the range of oxygen concentration level acceptable for each room in theprotected space and the associated alarms, with appropriate safeguards so that levelscannot be accidentally adjusted;

g) functionality for continued operation in the event of a power failure.

4.5 Design oxygen concentration level

The design oxygen concentration level shall be based on the results of the ignition-limiting

threshold determined in Annex B.


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The design oxygen concentration level shall be determined by subtracting not less thana 1% by volume safety factor from the lowest tested ignition-limiting oxygen threshold ofmaterials likely to be found in, or as part of the fabric of, the protected space.

NOTE 1 Alternative tests of the materials to be contained in the protected area can be conducted inaccordance with international standard methods for measuring ignitability using hypoxic air atmosphere

generated by a specific system for a specific application; or if agreed by the authority, a performance-basedapproach for specific applications may be used. However, in the event of challenge or dispute, thereference test method in Annex B should apply.

NOTE 2 A performance-based approach sets the agreed performance levels or acceptable limits for thematerials and compartment fire properties and conditions, including heat release rate, smoke emission orsmoke obscuration, ignitability, flame spread and flashover.

NOTE 3 When setting the design oxygen concentration level, consideration should be given to thebalance between ignitability of materials and health considerations of those persons working in theprotected area (see Annex D).

4.6 Indoor air climate

Consideration shall be given in the system design to the impact on the indoor air climate ofthe hypoxic air generation method.

NOTE A hypoxic fire prevention system may be installed, subject to design specification being met, as acomponent of the air-conditioning system.

4.7 Flushing

The system shall be designed such that, in circumstances when flushing using non-hypoxicair is necessary, the system can be taken offline.

NOTE 1 Flushing can be done in various ways, including opening doors/windows and using a ventilationsystem. The duration of flushing will depend on the mechanism and size of the hypoxic environment.

NOTE 2 The frequency of flushing (if any) will be dependent on the material stored, and so no timetablecan be provided in this specification.

NOTE 3 Due to the loss of fire prevention, flushing should be avoided as far as possible. Alternative fireprotection methods (e.g. fire watch) should be put in place before the hypoxic air environment is removed.

4.8 Monitoring

The system design shall enable performance to be monitored on a continual basis.

Performance indicators shall be, as a minimum:

a) oxygen concentration level as indicated by every sensor;

b) high and low oxygen alarm conditions;

c) system fail alarm.

These shall be transmittable to monitoring and control points (e.g. the fire alarm panel andthe building management system), as required.

4.9 Data retention

The system design shall enable the following data to be recorded and stored for a minimumof 12 months:

a) oxygen levels (minimum every 10 minutes);b) alarms (event-driven);


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c) duty cycle (event-driven).

A method shall be provided to retrieve information for analysis without compromising existingstorage or continuing data storage. Where this storage is not provided by external systemssuch as the building management system, then the hypoxic fire prevention system shallincorporate storage of this information.


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5 Installation, testing and maintenance

5.1 Installation

The installation of hypoxic fire prevention systems shall comply with the system designspecifications and include:

a) an air split unit (e.g. membrane, pressure swing absorption);

b) the control panel, wiring and power supply;

c) an oxygen-monitoring system;

d) pipes and/or ducting for feeding hypoxic air into the protected space and for disposing ofthe high-oxygen air stream into the atmosphere;

e) non-combustible pipes for hyperoxic air;

f) pipes from the compressor to the generator module and hypoxic air distribution pipes

within the protected space;g) a compressor and dryer.

NOTE A dedicated compressor/dryer system is recommended.

h) silencer system(s).

NOTE 1 The following are optional in the installation of hypoxic fire prevention systems: wiring to the firedetection and alarm control panel, to the building management system control panel and to remote displaysand indications; a water/oil separator; and pipes for clean water drainage.

NOTE 2 Electrical and mechanical equipment used in hypoxic fire prevention systems could be subjectto national regulations.

NOTE 3 Pipe types may include stainless steel, copper and flame-retardant plastic (as permitted under

conditions in sprinklers systems designed to BS EN12845).

NOTE 4 There is no equivalent standard yet available for control panels. The closest relevant standards,BS EN54 and BS EN 12094:1, are relevant for fire detection and alarm systems and for fire-extinguishingsystems, respectively. However, the control panel construction should at least meet national regulationsand the requirements for CE marking.

5.2 Testing

The completed system shall be reviewed and tested by a competent person in accordancewith the specifications of the system designer and installer, to meet the approval of theauthority:

a) A full visual inspection of all system components shall be carried out to ensure that thesystem has been installed in accordance with the design.

b) System performance tests shall be conducted and results verified against the systemspecification.

c) All inputs and outputs of the system control panel shall be tested to confirm performanceand functionality.

5.3 Documentation

Once the installation and testing are complete, documentation shall be provided to the

operator and authority by the installer and shall include the following, as a minimum:


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a) a completion document confirming the performance parameters of the system, signed bythe installer and commissioning engineer;

b) operation, maintenance and servicing instructions;

c) an installation report;

d) drawings showing the hypoxic fire prevention system layout;e) integrity (air leakage) monitoring and testing procedures for the premises;

f) commissioning data;

g) manufacturer's declaration of conformity;

h) guarantee documentation;

i) equipment datasheets with manufacturer and installer contact details.

NOTE 1 All modifications should be documented and carried out by a competent person. After anymodifications, a new system commissioning data report and an updated declaration of conformity shouldbe issued and documented.

NOTE 2 Where required, documentation should be signed for and/or approved by the authority.

5.4 Operation, maintenance and servicing instructions

The operation, maintenance and servicing instructions shall be provided by the systeminstaller to the authority and shall include, as a minimum:

a) date of installation, details of the installer and commissioning engineer, and drawingsand descriptions of the system operation and critical control functions;

b) testing and maintenance procedures for all system components;

c) manufacturers recommendations for system servicing and testing (see Annex E);

d) contact details for warranty and technical support;

e) recommendations for alternative fire protection when the system is likely to be shut downor inoperable for periods that extend beyond the hold time of the protected space,including notifying insurance and fire authorities;

f) action to be taken in the event of system fail alarm;

g) recommendations on keeping a logbook to record all system activity;

h) advice on health and safety procedures for persons occupying the protected space(see Annex D).


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Annex A (informative)Hypoxic fire prevention concept

Normal air contains 20.9% of oxygen by volume. As altitude increases, the volumetricproportion remains constant but the actual number of oxygen molecules reducesproportionally with decreased atmospheric pressure. As an example, in a commercial aircraftcabin space, the atmospheric pressure is 770mbar, equivalent to 2,200m altitude (at sealevel the atmospheric pressure is 1,013mbar).The actual percentage of oxygen at thisaltitude remains at 20.9% by volume, but its partial pressure is equivalent to a sea-leveloxygen concentration level of 15.8% by volume. In a hypoxic fire prevention system at sealevel, the balance of the air is essentially made up of nitrogen molecules. Physiologically, thehuman body cannot tell the difference between higher altitude air and the reduced oxygenair produced by a hypoxic air system.The change in proportion of nitrogen with respect tooxygen stops flame propagation and provides a fire prevention medium. This is why a firecan occur in an airplane but not in a correctly designed hypoxic atmosphere.

For every 410 metres above sea level, the available oxygen for respiratory purposesreduces by 1% by volume relative to that available at sea level.

Hypoxic atmospheres can be established with either a hypoxic air venting system or anitrogen injection system. Both systems create an environment with a reduced oxygen levelbut differ in the oxygen concentration of the airstream introduced into the area by thesystem. A generic arrangement is shown in Figure A.1.

Figure A.1 Hypoxic fire prevention system concept

Both systems are recognized as efficient methods of creating continuous hypoxic airenvironments for fire prevention. Once established, the oxygen concentration is monitoredand supervised constantly.

Hypoxic fire prevention systems need a finite time to generate the hypoxic atmosphere.Conversely, should they be deactivated for service or because of critical operation failure,the fire-preventing atmosphere remains in place for a period of time. In larger protectedvolumes, the period of extended protection may amount to many hours, or a day or more.


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This hold time, or reservoir effect, allows time for repair or for provisional measures to beestablished so protection can remain uninterrupted. However, taken in isolation, hypoxic airgenerators are active components that can potentially fail. If this compromises riskprotection, then means of addressing this through redundancy should be considered.


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Annex B (normative)Ignition-limiting oxygen threshold testing

B.1 PrincipleSolid materials shall be heated with a flame in a hypoxic fire-preventative environment toassess the ignition-limiting oxygen threshold.

NOTE The test method in VDS 3527:1997 Annex A5.2 may be used as an alternative to this test and fortesting liquids. However, in the event of challenge or dispute on solid materials, the test method given hereshould apply.

B.2 Test facility

B.2.1

The test facility shall consist of a 100m

3

space built to BS ISO 14520-1:2006 specificationsfitted with a hypoxic air supply system and an air lock in front of the entrance (see B.2.4).

The height of the room shall be at least 2m.

All penetrations by test set-up equipment, pipes, measurement cables and sensors shall besealed with non-combustible foam sealants.

There shall be no significant draft in the room, and control of the flame torch shall be remotewith no access to the space during the test.

NOTE 1 Under these conditions, this test may be performed in situ at much larger volumes as well, toaccount for large components in storage or special arrangements.

NOTE 2 Alternatively, spaces with volumes no less than 10m3may be used provided the oxygen

concentration level, measured as the mean reading of the two lowermost oxygen sensors (see B.5.2), iswithin a deviation of +/- 0.1% by volume during the test.

NOTE 3 The hypoxic air generation system may be a standard equipment set-up at the testing facility, orit may be a proprietary system that the user is assessing under standardized testing conditions.

B.2.2

The test facility shall be fitted with smoke extractor fans.

B.2.3

The test facility shall be fitted with opposing observation windows to allow observation of thefire test.

B.2.4

The test facility shall be equipped with an adjoining air lock vestibule of equal height andminimum 2.5m width x 1m length to limit air leakage.

It shall be equipped with doors and observation windows that are sealed with smoke sealant.

B.3 Test sample and specimens

The test sample shall be a batch of identical test specimens.

NOTE 1 Items with known properties from acknowledged sources such as those referenced inVdS 3527 Annex A5 (see Table B.1) need not be tested.

NOTE 2 The following materials are not suitable as test specimens: explosive mixtures of gases,particulates and liquids; reactive metals, cellulose nitrate, gunpowder, metal hydrides, hydrazine and otherchemicals capable of autothermal decomposition.


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Table B.1 Test sample exceptions


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B.4 Apparatus

The apparatus shall consist of the following items (see Figure B.1).

B.4.1

An oxyacetylene torch, with the ability to provide flaming exposure, regardless of the oxygen

concentration level or other room climate conditions.B.4.2

Three oxygen sensors, positioned within the test facility at heights of 0.2m, 1.2m and 2.2m ina vertical line, at least 1m away from the test sample on the opposite side to the torch.

B.4.3

A calibrated scale to measure specimen loss of weight.

B.4.4

Thermocouples, installed inside the room to measure temperatures.

B.4.5Data-logging equipment, installed to record readings throughout the test.

B.4.6

Video-recording equipment.

B.4.7

A heavy-gauge steel wire mesh frame, installed inside the room to support vertical samples.

B.4.8

A heavy-gauge metal-frame table with wire mesh, installed inside the room to supporthorizontal samples.

B.4.9

A heavy-gauge metal bracket to support the torch and its remote operation.

Figure B.1 Ignition-limiting oxygen threshold testing set-up


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B.5 Test procedure

B.5.1

The video-recording equipment (B.4.6) shall be set to record each test for review aftercompletion.

NOTE A review may be necessary for closer inspection after the test to establish whether there issmoking or not.

B.5.2

The specimen shall be placed on the metal-frame table (B.4.8) and fixed in a horizontalposition.

B.5.3

The oxyacetylene torch (B.4.1) shall be fixed on the bracket (B.4.9) such as to hit a lateralside of the test specimen. The flame nozzle shall be fixed at an angle of 90 degrees towards


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the specimen, with the flame outlet spaced 0.2m away from it and approximately 0.025minwards from the edge of the specimen.

B.5.4

The oxygen concentration levels of the oxygen sensors (B.4.2) shall be recorded using thedata-logging equipment (B.4.5).

B.5.5

The test facility shall be filled with hypoxic air so that the oxygen concentration level is at thedesired value.

B.5.6

The unobstructed length of the torch flame shall be set to 0.3m. The test specimen shall besubjected to a flame set at the transition point from orange to blue colour for 180 seconds.

B.5.7

It shall be observed whether the test specimen ignites.

B.5.8

The loss of weight to the specimen during the test shall be measured using the calibratedscale (B.4.3). Specimen weight before the start of the test and 180 seconds after removingthe torch flame (post-exposure time) shall be recorded. The specimen shall be observed fora further 60 seconds to see whether it continues to produce flames independently of thetorch, and its weight then recorded again.

NOTE It may be useful to produce a graph to chart weight loss throughout the test.

B.5.9

A new specimen from the same batch shall be fixed in the vertical position on the metalframe (B.4.7).

B.5.10

Provision B.5.3 shall be repeated, but with the flame pointing towards a lowermost corner ofthe vertical specimen.

B.5.11

Provisions B.5.4 to B.5.8 shall be repeated.

B.5.12

The tests shall be repeated (at least twice more) for each sample, each time with the oxygenconcentration level being decreased by 0.5% by volume, or as agreed otherwise, until theignition-limiting oxygen threshold is established.

B.5.13

The air inside the test room shall be exchanged before carrying out the test with horizontalconfiguration and before carrying out the test with vertical configuration, to keep conditionsconsistent (room temperature at 20C and no air pressure differential to the outside).

B.5.14

For each type of specimen and configuration, a reference test shall be performed todetermine ignition and burning properties in normobaric normoxic conditions.

NOTE Local health and safety and environmental regulations for handling hazardous materials should beconsulted.


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B.6 Test documentation

B.6.1

The following shall be recorded prior to the test:

a) test specimen configuration;

b) spacing of specimens (if multiple specimens are tested);

c) torch location, flame colour, angle towards and distance from specimen;

d) material:

weight (grams);

dimensions (metres);

type and shape;

packaging (if any);

e) system:

type of hypoxic air supply;

date of manufacture;

manufacturer name;

capacity of hypoxic air flow generator and oxygen concentration level (% by volume);

for nitrogen gas injection hypoxic air systems, capacity in terms of nitrogen air flow andnitrogen concentration level (% by volume).

B.6.2

The following shall be recorded during each test:

time of exposure (seconds) of the test specimen to the flame;

ignition time (seconds) after exposure to the flame;

weight loss (grams) during flame exposure and during the post-exposure observationperiod;

oxygen concentration level (% by volume) in the room throughout the test;

observation of any smoke generation throughout the test;

observation of sustained flaming (duration in seconds) after removal of the flame;

temperatures in the room (C).

B.7 Test criteria

B.7.1

The measured ignition-limiting oxygen threshold shall be recorded when tests of identicalsamples tested both horizontally and vertically have passed the following criteria:

a) no self-sustained burning or spread of fire observed on the sample beyond the areadirectly hit by the torch flame during 180 seconds of exposure to the flame;

b) no self-sustained burning or spread of fire observed on the sample for a durationof 60 seconds after removal of the burner flame.


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B.7.2

Pure, mixed or encapsulated specimens that are subject to glow, rekindle or smoulder byoxidation shall be tested by the procedure given in B.5. An extended period of observationduring the post-exposure time shall then apply, the length of which shall be set by thelaboratory.

B.7.3

The ignition-limiting oxygen threshold for the system shall be set as the measuredignition-limiting oxygen threshold reduced by a safety factor of 1% oxygen concentrationlevel by volume.


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Annex C (informative)System specification: graphical representations

Figure C.1 Example of graphical output of key design parameters, including leakage,minimum/maximum oxygen concentration level, time to reach design oxygen

concentration level, compressor output and duty cycle

Y-Axis Oxygen concentration (% by volume)

X-Axis Time (hours)

Key: Dark red Oxygen concentration in continuous operation without set

maximum/minimum oxygen levelsLight Red Maximum set oxygen concentration level

Green Minimum set oxygen concentration level

Blue Oxygen concentration level in normal operation with setmaximum/minimum oxygen concentration levels

System data

Room volume 770m3(770,000 litres)

Inward leakage of ambient air 1.5% of volume per hour (192.5 litres/hour)

Inward flow of hypoxic air at 10% 750 litres/minute, equivalent to 5.8% of volume per hour(140% per day). This requires a compressor outputof 1,485 litres/minute

Starting oxygen concentration level 20.9%

Minimum set oxygen concentration level 14.5%

Maximum set oxygen concentration level 15.5%

Duty cycle of compressor 31%

Figure C.2 Demonstration of hold time


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Y-Axis Oxygen concentration level (% by volume)

X-Axis Time (hours)

Legend: Dark red Oxygen concentration level

System data (volume and leakage data identical to those in Figure C.1)

Room volume 770m3(770,000 litres)

Inward leakage of ambient air 1.5% of volume per hour (192.5 litres/hour)Inward flow of hypoxic air at 10% 0 litres/minute

Starting oxygen concentration level 14.5%


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The data given are applicable for locations from sea level up to approximately 500m.Above 500m, the effect of altitude on the oxygen availability in a protected space should betaken into account.

D.2 Workload

For persons exposed to controlled hypoxia in a protected space, workload is not arisk-determining factor, as they will simply exhaust, as when performing physical work in anormoxic environment at loads that are too high for their level of fitness or acclimatization.

D.3 Risk profile

Although there is a linear decrease of oxygen partial pressure with a decrease of oxygenconcentration level, the risk for persons is non-linear for several physiological reasons. Infact, up to the so-called threshold altitude at about 17% oxygen by volume (equivalent to

an altitude of 1,500m), the body does not realize that something has changed (detaileddiscussion in [2]). Further decreases below 17% result in physiological short-termadaptations occurring. Many of them shift the sigmoidal oxygen-binding curve of the redblood cells to the safe side. For healthy persons, the following potential risks have to betaken into account when they are exposed to controlled hypoxia (see also Table D.2).

D.3.1 Acute cerebral/mental incapacity

As given in Table D.1, this can occur in extreme hypoxia only, below 10.4% oxygen byvolume, equivalent to 5,500m altitude). Unconsciousness can occur if these thresholds areexceeded for more than 30 minutes, reducing to a few minutes as oxygen concentrationlevel continues to fall.

D.3.2 Acute mountain sickness (AMS)

Headache and nausea may occur at approximately 15.4% oxygen by volume, equivalentto 2,500m altitude, if the person is continuously exposed for at least 6 hours. Typically, anyproblems take 824 hours to materialize. At 11.8% oxygen by volume, equivalentto 4,500m, 50% of persons exposed for more than 46 hours and without previousacclimatization suffer from AMS. Any such symptoms rapidly reverse when the personre-enters a normoxic environment.

D.3.3 Other risk considerations

D.3.3.1 Pregnancy

According to international recommendations (e.g. [3], [4]), pregnant women may be exposedup to 14.5% oxygen by volume, or 3,000m altitude, if there is no or minimal workload.

NOTE This recommendation is on the safe side as in some countries (e.g. USA) physicians for altitudemedicine give 4,000m as the limit.

D.3.3.2 Young people

Young people do not have any age-specific increased risk when they are exposed toaltitude. Therefore the same recommendations as for adults should be used.

D.3.3.3 Older people

The risk for older people is defined not by hypoxia or duration of exposure but bypre-existing conditions (see below). Without any such conditions (especially of the heart orthe lung), they show the same risk as younger adults with the same exposure.


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D.3.3.4 Race/ethnicity

The race of the person exposed is not a risk-determining factor within the range discussedhere (up to 13% oxygen by volume, or 3,800m), but the region of origin may predispose tosickle-cell anaemia, which may cause significant symptoms at class 2 hypoxia(see Table D.2).

D.3.3.5 Pre-existing medical conditions

People with pre-existing medical conditions may have an increased risk compared withhealthy persons under the same conditions. This does not automatically exclude thesepersons from work in hypoxic environments, but advice should be sought [5].

D.4 Safety procedures

Safety procedures should take into account the characteristics of the respective exposure asmentioned above (% oxygen by volume, duration, individual pre-existing conditions). Asummary based on the facts mentioned above is given in Table D.2.

Table D.2 Risk classification of hypoxia and actions recommended asprecautions

Hypoxiariskcategory

Oxygen in inspired air Summary of risk Precautions

%O2 Equivalentaltitude

pO2

[%] [m] [mmHg]

Class 1

17 01,600 760620 No risk Advise employees(see Figure D.1)Class 2 16.9

14.81,6002,700

620550

No risk for a fulldays shift ifsevere diseases ofthe lungs or heartand severeanaemia areexcluded

Exclude severediseasesAdvise employees(see Figure D.2)

Class 3 14.713.0

2,7003,800

550480

No risk if diseasesare excluded asmentioned for

class 2, theworkload is limited(see Table D.3)and the duration ofexposure does notexceed 4 hours/day or 2 x2 hours/day withhigh workload

Exclude severediseasesCheck workload

level(see commentbelow)Advise employees(see Figure D.3)

Class 4 3,800


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occur fornon-acclimatizedpersons

The majority of hypoxic fire prevention systems operate in the class 2 category.

D.5 Signage for environment

Appropriate warning and instructions signs should be installed notifying personnel of thepresence of hypoxic fire prevention systems and authorization requirements for accessingthe area.

The following wording is suggested.

a) You are entering a controlled environment with lower than normal oxygen levels. If youdo not have the appropriate authorization, please report to xxx.

b) If you feel shortness of breath or any other unusual symptoms, you should leave the

environment immediately and inform your supervisor.

D.6 Health and safety assessment

D.6.1 Stage 1: questionnaire for persons likely to enter a hypoxic environment

a) Do you have any known heart disease?

b) Do you have any known lung or airway disease?

c) Do you have anaemia?

d) Do you have, or have a family history of, inherited blood disease, low blood count,anaemia or sickle-cell anaemia?

e) Did you experience any pains (with the exception of headaches), such as abdominal,chest or joint pains, nausea, vomiting, shortness of breath or fatigue during previousstays at high altitude (mountains) or during airplane flights?

f) Have you ever had a stroke or a mini stroke (transient ischaemic attack)?

g) Have you ever been treated for rhythm problems of the heart?

h) Have you had any episodes of dizziness within the last 3 months that have preventedyou from pursuing your normal daily activities?

i) Do you have to pause during your daily activities at work or at home because ofshortness of breath?

j) Have you experienced any chest pain within the past 3 months while at rest, or whileunder physical or mental stress?

k) Have you woken up in the past 3 months because of shortness of breath?

l) If female, are you currently pregnant?

m) Are there any known medical issues that you think might affect you working in alow-oxygen environment? If so, please specify.

n) Is your doctor currently prescribing drugs (for example, water pills) for your bloodpressure or heart condition?

If the person responds with YES to any of the above statements, they should be referred to

a qualified physician to determine whether they should be allowed to enter the hypoxicenvironment and, if so, under what limitations (if any).


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D.6.2 Stage 2: further examination by a qualified physician

It is important that this supplementary examination should be performed by a physician whohas relevant environmental physiology experience and the technical equipment necessary.They should provide a report to the organization and advise on what controls or limitationsshould be enforced with the individual relative to hypoxic conditions.

D.7 Common topics and questions raised

Table D.3 Common topics and questions raised

Topic Comment

Pregnancy:What if I am pregnant?

According to international guidelines,pregnant women should not be exposedto class 3 or 4 hypoxia. They can be

exposed to class 2 hypoxia, but forminimal workload only (e.g. inspection,supervision)

Comparison with air travel:How does the hypoxic environmentcompare with an aeroplanes cabin?

For classes 1 and 2 the hypoxia does notexceed the hypoxia of an aeroplanecabin. This gives the person an idea howhe/she will experience the environment

Inflow exposure risk:Avoid direct exposure to the inflowdevices. Stay at least 1.0m from theinjector orifices

This provides further safety, particularlyin relation to nitrogen injection systems

Acute mountain sickness (AMS)symptoms:Some dizziness, headache or nauseamay occur if persons are subject toprolonged class 3 or 4 hypoxia.If these symptoms disappear within lessthan 30 minutes after you have lefthypoxia, you may enter again; otherwise,contact a physician.If symptoms reappear after you havereturned to hypoxia, specific advice by aphysician trained in altitude

medicine/hypoxic environments isnecessary before you enter hypoxiaagain

This provides further safety, since it iswell known that AMS-related symptomsdo not occur quickly or immediately. Anyhypoxia-related symptom that disappearswithin some minutes in normoxia is notdangerous, and therefore a re-entry tohypoxia is possible

Alarm system/emergency exit:If there should be any alarm signal by thehypoxia system, leave the hypoxic areaimmediately (but do not run in anuncontrolled manner, to avoid additionaldanger or accidents). Any furtherprocedure should be discussed outside(in normoxia) when the reason for thealarm is known

Gives clear advice in case of (possible)emergency


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Figure D.3 Protocol for working in a class 3 hypoxic environment


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Figure D.4 Protocol for working in a class 4 hypoxic environment

Note: The oxygen levels described here would be highly unusual in an occupied, protectedenvironment and would only be utilized where material in the protected space required theselow oxygen levels to impede combustion.


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Annex E (informative)Servicing

The servicing instructions provided by the installer should include the following:

a) compressors are to be checked weekly by the operator;

b) if pressure vessels are used, servicing instructions in accordance with the regulations forthe country of operation;

c) air locks and other critical points of potential leakage are to be inspected on a quarterlybasis.

A suitable procedure for verification of the system is as follows:

a) daily, verify oxygen levels;

b) every 3 months, test and service all electrical detection and alarm systems asrecommended in BS EN 5839 Part 1;

c) every 3 months, check oxygen sensors and the oxygen-monitoring systems. They should

be compared with a separate calibrated device;

d) every 6 months, perform the following checks and inspections:

externally examine pipework to determine its condition; replace or pressure test andrepair as necessary pipework showing corrosion or mechanical damage;

check all valves for correct function;

review the duty cycle. An increase would indicate more access events than designed foror that the area of leakage has increased from that measured during installation, whichwould adversely affect system performance; carry out work to reduce the leakage oramend design to cater for additional access events.


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Bibliography [to be styled]

Standards publications

For dated references, only the edition cited applies. For undated references, the latestedition of the referenced document (including any amendments) applies.

ASTM E 779-99, Standard test method for determining air leakage rate by fan pressurization

BS EN 13829:2001, Thermal performance of buildings Determination of air permeability ofbuildings Fan pressurization method

BS EN 15004-1:2008, Fixed firefighting systems Gas extinguishing systems Part 1:Design, installation and maintenance

ISO 14520-1:2006. Gaseous fire-extinguishing systems Physical properties and systemdesign Part 1: General requirements

ISO 16000-8:2007, Indoor air Part 8: Determination of local mean ages of air in buildingsfor characterizing ventilation conditions

ISO/DIS 12136, Reaction to fire tests Measurement of fundamental material propertiesusing a fire propagation apparatus

NT VVS 118:1997, Ventilation: local mean age of air homogeneous emission techniques(Nordtest method)

VdS 3527, Guidelines for inerting and oxygen reduction systems Planning and installation

Annex D references

1. Kupper, T, et al. Consensus Statement of the UIAA Medical Commission Vol.15: Work inHypoxic Conditions. 2009 [

2. Kupper, T, [Workload and professional requirements for alpine rescue]. Professoral thesisat Aachen Technical University / Germany, 2006 (english publication in preparation), Dept.of Aerospace Medicine. Aachen Technical University: Aachen 2006,.

3. Jean, D, C Leal, and H Meijer. Consensus Statement of the UIAA Medical CommissionVol.12: Women Going to Altitude. 2008

4. Jean, D, et al., Medical recommendations for women going to altitude. High Alt MedBiol,2005. 6(1): p. 22-31, 2005.

5. Milledge, J and T Kupper. Consensus Statement of the UIAA Medical CommissionVol.13:People with Pre-Existing Conditions Going to the Mountains. 2008 ;

Further reading

Allianz Risk Consultants. Loss control guideline: Fire protection with low oxygen orOxy-Reduct principal concepts. Switzerland, Allianz Risk Consultants, April 2004

Angerer P, Nowak D., Working in permanent hypoxia for fire protection-impact on health,Journal of international archives of occupational environment and health., 76, 2, 87-102.,February 2003

C A Boman, J Holmberg, H Stymne, Monitoring of Air Infiltration in Museums, Case Study:The National Museum of Fine Arts, Stockholm, Sweden, The 6th Indoor Air Quality Meeting,Padova, November 2004

Chiti, S. Test methods for hypoxic air fire prevention systems and overall environmentalimpact of applications. Universit a degli studi di Modena e Reggio Emilia, faculty of


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Engineering di Modena, Master Thesis, Academic Year 2008/2009. Reprint COWI FireResearch Report 01/2010.

CIBSE TM 23, testing buildings for air leakage, CIBSE, UK, 2000

European Guideline - Fire Protection in Information Technology Facilities, CFPA- EGuideline No. 14:2007, CFPA, 2007

FPA Guidance Note - Low oxygen atmospheres and the risk control of associated healthhazards, The Fire Protection Association, UK, 2006

Friedman, R, Principles of Fire Chemistry and Physics, NFPA, 3rd Ed., Quincy, MA, USA,National Fire Protection Association, 1998

Fu Q, Townsend NE, Shiller SM, Martini ER, Okazaki K, Shibata S, Truijens MJ, RodriguesFA, Gore CJ, Stray-Gundersen J, and Levine BD, Intermittent hypobaric hypoxia exposuredoes not cause sustained alterations in autonomic control of blood pressure in youngathletes. American Journal of Physiology Regulator, Integrated, and ComparativePhysiology 2007, 292, 5, R1977-R1984.

Huggett, C, Habitable atmospheres which do not support combustion, Combustion andFlame,20, 197, 140-142, 1977

Jensen, G. Clearing the Air, Fire Prevention Fire Engineers Journal, March 2007, 51-53

Jensen, G, Holmberg, J G, Gussias, A, Melgard, M, Fjerdingen, O T. Hypoxic Air Venting forProtection of Heritage. Jointly published by Riksantikvaren the Norwegian Directorate forCultural Heritage and Historic Scotland: Technical Conservation, Research and EducationGroup, in support of COST the European CO-operation in the field of Scientific andTechnical Research Action C17 Built Heritage: Fire Loss to Historic Buildings, 2006

Madsen N., Jensen C., Holmberg J.G., Hypoxic air venting fire protection for librarycollections, World Library and Information Congress: 71th IFLA General Conference andCouncil, "Libraries - A voyage of discovery", IFLA; Oslo, Norway, August 14th - 18th 2005,.

National Research Council of the National Academies of Science, Emergency andContinuous Exposure Levels of Contaminants, Washington DC, USA NRC- NAS,Volume 1, 2007

UNINETT, Research Network in Norway, - Requirements for fire detection and fireprotection, UFS No.: 104, Version: Version 2, Approved draft, 02. 07. 2008, Physicalinfrastructure workgroup, UNINETT, Oslo, Norway, 2008.

R E Shave, E Dawson, G Whyte, K George, D Gaze, P Collinson, Effect of prolongedexercise in a hypoxic environment on cardiac function and cardiac troponin, British Journalof Sports Medicine 38, 86-88, 2004

SINTEF,, Fire Protection Solutions for Rooms with Sensisitive Contents, SINTEF,Byggforskerien, 550.363, Byggforsk ,Oslo, April 2009

Online resources

http://heritagefire.net/heritage_fire_wg_papers/wg2/wg2_Inert_Air_Libraries_IFLA_

English.pdf

http://www.gbshaun.com/altitudeforall//hypoxia_resources_scientists.html

http://www.theuiaa.org/medical_advice.html.


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