Plumis Automist Series Quick start guide

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AutomistTM Technical Guide
Product specication and technical results from a test suite at BRE Global to
enable building control and re industry professionals to assess or specify Automist.
Plumis Ltd.
Seamless Fire Protecon
www.plumis.co.uk
A technical guide for:
- Building Control
- Fire Industry Professionals
New Edition
Version 2.5.0
RD171

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1 This Document Page 3
2 Introduction to Automist Page 3
3 System Diagram Page 4
4 Automist Operation Page 6
5 Quality Assurance Page 6
6 Components and conguration Page 7
7 Fire suppression within a holistic approach Page 9
8 Fire Performance and Regulations Compliance Page 10
9 Use of Automist Page 15
10 Specifying Automist Page 17
11 Conclusions Page 19
12 Appendix Page 20
The aim of Automist is to aid in the detection and control of dwelling res and thus provide improved protection
against injury, life loss and property damage. When correctly installed and maintained in accordance with its
instruction manual, Automist is designed to operate in a manner similar to that demonstrated in the testing
performed at BRE Global, subject to a reliable power and water supply and a correctly operating alarm input. The
effectiveness of Automist is however dependent on factors such as the size of room, detection method, environmental
conditions, available fuel, the source of the re, availability of ventilation, human behaviour and health, distance
to the re, time to activation and the actions of the emergency services upon arrival. Plumis therefore cannot make
warranties regarding detection, control, suppression or extinguishment of res, nor the prevention of injury, death
or property damage.
Contents

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Automist is a re suppression appliance designed for residential use. Its primary application is in the gap
between standardised sprinkler systems, which are designed to provide suppression to every room in a
property, and building and housing regulations, which in many circumstances require re suppression in a
single open-plan “access room”.
All major UK guidance documents on residential re safety, including Approved Document B, The LACoRS
guide, and Scottish Building Regulations, recognise re suppression as a compensatory solution for layouts
where the provided compartmentation is not adequate on its own, and divide the solutions into two
categories:
• Standardised products, generally “off patent” using long-established technologies;
• Innovative products, which have not yet been standardised, often patent protected and proprietary.
In both cases, it is essential that products have been adequately tested. For Standardised products,
strengths and weaknesses need not be evaluated for every project, as assessors can rely on the standards to
short-cut some of the regulatory formalities. For Innovative products, a similar short-cut is available in the
form of the LABC Registered Details Scheme.
Automist is covered by Registered Detail (RD171). Those wishing to
compare Automist directly to a conventional BS9251 sprinkler system in
greater detail should refer to section 8.2 of this guide.
The recent introductions of BS9991 and PD7479 illustrate the limitations
of an approach to re safety driven wholly by product categories; the new
standards have a broader reach, allowing Fire Engineering skills to be
applied to residential re safety strategy, inherently embracing the use of Innovations in re safety through
rigorous analysis of limitations and solutions.
The objective of this guide is to provide information on the performance, specication and installation
of Automist. With this guide as a route map, speciers and approvers can feel condent in specifying
Automist.
Intended as a more practical and affordable alternative to sprinklers, Automist uses a high pressure pump
to generate a ne water mist from nozzles mounted under a standard tap, on a work surface or in a wall.
In an extensive BRE test programme, Automist was found to render a lethal environment survivable.
Automist is a water mist innovation which provides developers with greater design freedom and exibility
of layout, in new builds, refurbishments or loft conversions.
1 This Document
2 Introduction to Automist
1. The LABC Registered Detail logo is a collective mark registered by LABC.

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Two examples of generic system layouts are detailed on the following pages. As an “pre-engineered”
solution which is not covered within any one British Standard the following system layouts are proposed
as our recommendations, however these may need modication during the course of negotiation with
approving authorities with regard to a specic project specication.
a) Automist wall-mount kit (3N)
3 System Diagram
A discreet single-gang wall box
holds the water mist spray head
in place.
The pump can be housed in a
cupboard, under a staircase or
within a custom box unit.
Stainless
steel braided
3/4” water supply

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b) Automist under-tap kit (4N)
Assembled Automist emitter
- outer cover and o-ring
- manifold and two o-rings (base & upper)
- six protective caps
- four watermist nozzles
High
pressure
hose
Stainless steel braided
3/4” water supply
hot & cold water
supply pipes
Fused
connection
unit on a
separate
circuit
Automist
supply label &
cable tie
Wired or wireless heat
alarm with NC and NO
relay functionality
Standard
monobloc tap
¾” single
check valve
¾”
washing
machine
outlet with
isolation
valve
Automist
Pluvia Pump

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In the event of a re, the system is triggered automatically by a heat alarm or a re panel output. Heat
detection is recommended for kitchens in Approved Document B, and effectively eliminates nuisance
activation. Unlike conventional sprinklers, Automist can be stopped manually by pressing a button on
its control panel or by cutting power to the independent circuit on the consumer unit (marked with an
indicator sticker). As Automist uses much less water than a traditional sprinkler system, water damage
in the event of activation is minimised. Where desired, manual activation can also be provided through a
manual call point.
Once triggered, a pump drives mains water through the unique nozzle unit, quickly lling the room volume
with a dense fog. Water mist removes heat and displaces oxygen from the re zone, resulting in re control,
suppression or extinguishment. The intention is to lower the temperature and the accumulation of toxic
gases, thereby reducing damage and increasing survivability.
Adding water to a chip pan re can greatly exacerbate the re; the same is not true for water mist as the
updraught from the ame and the evaporation of the tiny droplets prevents water from reaching and
collecting in the pan.
The water mist technology also has benets for suppressing a greater range of re scenarios, particularly
res that are shielded from the nozzle release point.
Concept
• Independently tested - Objectively and extensively tested by BRE Global (further details in
Appendix)
• All concept proposals are underpinned by British Standard re engineering justication.
Equipment & Components
• CE marked - Meets EU consumer safety, health & environmental requirements
• Water Regulatory Advisory Scheme Approved - Automist re suppression system was examined,
tested and found, when correctly installed, to comply with the requirements of the United Kingdom
Water Byelaws (Certicate number 1102330)
Installation
• Installation - Automist should be specied, commissioned and signed-off by Plumis or an Accredited
Reseller. Each installer is fully trained to ensure that every project is installed to the very highest
standards, receiving a Plumis Certicate of Approval on successful completion of their training.
4 Automist operation
5 Quality Assurance

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Automist should be mains fed with a reliable water supply:
• 6 l/min ow
• 1-10 bar pressure at pump inlet
• Standard BSP ¾” connection. For life safety applications exposed or partially exposed pipework
must be in copper or steel for robustness.
The Automist pump should be:
• Proper air circulation must be provided. The system requires there to be a minimum 100 mm gaps
are gap between the pump perimeter and the enclosures.
• Protected electrically by suitable fusing and powered by an independent circuit either via a delayed
action RCD or no RCD (1.7kW, 230V and 50Hz) with an unswitched fused connection unit with
ex outlet. FP200 re rated power cable must be used to supply the unit. If the consumer unit is
located in the protected area it should be shielded by a fuse box electrical cover unit tested to BS476
Part 22 (1987) and EN1364-1 (1999).
6 Componentsandconguration
under sink
cupboard
separate circuit
Example:

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The Automist unit will be activated by an alarm which will ensure that:
• Audible warning is provided throughout the protected area.
• In addition to Automist’s integrated sounder, we recommend that the detector or alarm system
that activates Automist also includes its own sounder.Guidance on re detection in dwellings is
contained in BS 5839: Part 6.
• Automist must not be activated by an early warning interlinked system (which might include smoke
alarms). A separate alarm circuit should be used or provisions should be made so that a smoke
alarm can sound the heat alarm connected to Automist but will not trigger the pump unit.
• Where a single Automist unit is used to protect more than one area by use of multiple mist heads,
the activating alarms must be interlinked so that any heat alarm sounding in the protected areas
will activate the Automist unit. Where multiple Automist units serve a single area, these must be
similarly interlinked with a separate relay output provided for each Automist unit.
• Where a re resisting construction separates two protected areas with one or more Automist units
serving each area, it is not normally necessary to interlink the activation between these separate
areas.
Installation ow valves:
• Check valve should be installed to ensure back ow protection to the mains water (supplied in kit).
• Approved Isolation valves should be included to shut off the Automist system from the mains. The
valves should be labelled with the included Automist supply warning labels.
• Priority valves are not normally required but should be used in circumstances where the water
supply may otherwise be inadequate.Electrical components used within the installation must.
• Comply with the relevant guidance in BS 5839 Part 6.

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A re suppression device like Automist aims to control and suppress res, signicantly reducing the risk
of injury, life loss and property damage by maintaining tenable conditions for as long as possible while
occupants evacuate. This is achieved in several ways:
• Reduction of room temperature in the region of the re. Water mist devices achieve this by
consuming much of the re’s energy in converting water to steam.
• Reduction of smoke and toxic gases. Water mist devices achieve this by the production of copious
amounts of steam in the immediate vicinity of the re, locally excluding oxygen, reducing
temperatures and thus inhibiting the combustion reactions of the re.
• Fire growth is restricted. This is achieved through the reduction in temperatures and slowing of
combustion reactions.
• Flashover prevention. By constraining room temperatures to around 100°C or less, the rapid
ignition of all combustible items in the rooms is prevented.
• Providing cooling to structural elements in the re compartment allows them to perform their
function for longer.
Utilising Automist’s benecial suppression capabilities as part of a package of building design measures
may offer an alternative, more exible and desirable solution to those prescriptive approaches offered by
design guidance such as Approved Document B.
7 Fire suppression within a holistic approach

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All new or modied buildings constructed in the UK are required to meet the functional requirements of
the Building Regulations. Guidance for meeting these requirements are outlined in various codes such as
Approved Document B (ADB), supported where applicable by a wide range of British Standards.
For existing buildings the Regulatory Reform (Fire Safety) Order 2005 applies, with rented residential
properties also being subject to the provisions of the Housing Act 2004. These laws require properties to
maintain reasonable standards of re safety. Again, publically available guidance has been produced to
outline what are considered to be reasonable standards of safety, with many being more risk assessment
based than the guidance applicable to new buildings.
In the last four to ve years re suppression systems, particularly residential sprinklers, have gained
recognition in the various national guidance documents as one method of improving the level of re safety
such that the functional requirements of the Building Regulations are met. In August 2011 the draft
British Standard BS9991 proposes further embracement of re suppression as a means of creating design
exibility.
Whilst the above guides have focused specically on residential sprinklers they do not exclude any form of
re suppression as a potential alternative. Paragraph 0.18 of Approved Document B, Volume 1 2006 states,
“0.18. There are many alternative or innovative re suppression systems available. Where these are used
it is necessary to ensure that such systems have been designed and tested for use in domestic buildings
and are t for their intended purpose.”
An identical statement to that above is also included at the end of paragraph 0.16 of Approved Document B,
Volume 2, 2006.
Further to the specic comments above the opening paragraphs in Approved Document B enable
re engineering to be used as an alternative approach to achieving compliance with the functional
requirements of the Building Regulations. The BS7974 suite of documents provides a structured approach
and methodology for preparing re engineered solutions. This suite discusses re engineered solutions
generally in terms of comparative, deterministic and probabilistic approaches. The remaining parts of this
section outline the philosophy and details for why Automist forms an effective and robust means of re
suppression suitable for life safety applications. These proposals are further explored at a generic concept
level in Section 9.
8 Fire Performance and Regulations Compliance

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8.1 Automist Concept
Water mist technology has been applied for several years to the marine industry and is also used for some
specic applications in buildings. Clearly the use of water mist technology deserves recognition as a means
of suppressing res.
In one of the most comprehensive test suites ever run on a mist product at the Building Research
Establishment (BRE), Plumis veried the effectiveness of Automist with live burns in a series of different
scenarios. The test was based on BS EN 1869:1997, DD 8458 1:2010, and the criteria of Scandinavian
SRSA/DSB “Easily installed automatic extinguishing systems”. Critically, Fractional Effective Dosage (FED)
measurements and “free burn” control tests were included to allow a complete and objective assessment.
These tests were run in BRE Global’s Watford (UK) Burn Hall and mimicked both furniture and kitchen
res.
In every test where a “free burn” unsuppressed reference was available, the system produced an
improvement in both temperature and asphyxiant gas conditions, whilst reducing damage. Automist was
found to render lethal environments survivable. In a major furniture re, even those immobilised in the
room could have survived for the entire test period of 30 minutes. A more in depth discussion of the BRE
re testing is included in Appendix A.
450
Temperature (°C)
400
300
350
150
250
200
0
100
50
024 6 8 1210
Time (mins)
8m x 4m x 2.5m
Temperature
0.8m high and 2m
from a furniture
re
control
automist

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The application of Automist is carefully controlled to ensure that the application does not extend beyond
the system capabilities that were established during the BRE re tests. The general rules developed from
these tests are included in Section 10 of this document and form the basis of proof of concept for the
suppression performance for all actual applications.
Where the focus of the Automist application is not something that was directly considered during the BRE
re tests the behaviour has been further validated by independent re engineering consultants following
recognised re engineering principles discussed in BS7974 to demonstrate suitability for that application.
Such applications and validation are discussed in Section 9 later.
8.2 AutomistSystemConguration
At a system performance level it is necessary to demonstrate that Automist is “t for purpose in domestic
buildings”. As discussed earlier, at a component level the Automist system is CE marked as meeting EU
consumer safety, health & environmental requirements. Additionally Automist is also approved under the
Water Regulatory Advisory Scheme.
As an installation for life safety applications it is proposed that providing the systems physical installation
is of a comparable standard and connection to both electrical and water supplies as for the recognised
residential sprinkler system then the system would demonstrate an adequately robust system, suitable for
application in residential settings.
024 6 810
Time (mins)
5.0
FED Heat
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
8m x 4m x 2.5m Open
Room FED Heat -
when it reaches 1.0
it is assumed that
an occupant will
be incapacitated
due to pain. Third
degree burns are
predicted at an FED
of approximately 3.0
control
automist

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The following table discusses the individual elements and recommendations of BS9251 (component layouts
for a residential sprinkler system that is currently considered to be of an adequate standard for life safety
applications) and compares these to the conguration of Automist systems.
Design
Aspect BS9251 Recommendations Automist Comments
Suppression
system
Domestic cold water wet pipe
system, operating pressure
0.5 bar
Pre-engineered
domestic cold water dry
pipe system, operating
pressure 80 bar
Activation Fusible link or glass bulb
sprinkler heads which have
an activation temperature
in excess of 20oC above the
highest expected ambient
temperature.
BS5446 Part 2 Heat
Detector/Sounder
Achieved. Automist uses
proven technology used readily
in life safety re alarm and
detection systems.
Activation
temperature
57oC or 68oC for most general
applications
57oCAchieved. The Heat
Detection used for Automist is
more likely to respond earlier
than a concealed sprinkler
head.
Warning
Device
An audible alarm operated
from an electrically operated
ow switch.
BS5446 Part 2 Heat
Detector/Sounder
linked to the Automist
control panel and water
mains supply valve.
Achieved.
Areas of
Coverage
Whole house / apartment
coverage
Identied re risk
room(s)
Achieved. As a re
engineered system the areas
of coverage can be varied to
address the required risk. It
should be noted that even with
sprinkler coverage everywhere
only the heads exposed to
elevated temperature will
operate so the behaviour is
identical to Automist.
Water supplies Mains or tank supplied
providing a minimum 60 l/
min to one sprinkler head
or 42 l/min through at least
two sprinkler heads (subject
to domestic or residential
classication)
Mains fed providing a
minimum 5.5 l/min.
N/A. Being water mist based
Automist uses approximately
10% of the water requirements
for residential sprinklers and
therefore does not require
changes to the water mains
connection.
Water supply
tolerance
Minimum operating pressure
of 0.5 bar. Where mains
supplies are used then either
a priority valve should be
used or the system is designed
to operated with either a 25 l/
min or 50 l/min depending on
the system classication.
A reliable 1-10 bar
pressure at pump inlet.
Achieved. An identical
level of design redundancy is
included into the Automist
system as would be expected of
a residential sprinkler system.

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Electrical supplies A separately fused
connection to the re
pump taken after the
meter and from the
supply side of the
domestic fuse box using
re resisting cable. All
other devices on the
system should continue
to function in the event
of a complete failure
of mains power (as per
BS5839 Part 6)
Automist must remain
powered in the event of
a re and therefore must
not share a mains circuit
or RCD with appliance and
sockets. The pump unit
electrical supply will adopt
the BS9251 installation
recommendations.
Achieved. An identical
level of design redundancy is
included into the Automist
system as would be expected
of a residential sprinkler
system.
Installation Requires an Approved
Installer to run pipes
from the services routes
and sign off the system
installation.
Requires a Plumis
Certied and Approved
Installer and/or Reseller to
install Automist correctly.
Achieved.
Typical run time Minimum of 10minutes
for domestic occupancies
and 30minutes for
residential occupancies.
30 minutes (default) or
congurable with the re
panel
Achieved. Due to the lower
water supply requirements
the Automist is capable
for being run for extended
periods more easily than
residential sprinklers with
less potential water damage.
Commissioning Pressure test to 1.5 times
the working pressure or
12 bar for 1 hour. Plus a
pressure and ow test.
A simple commissioning
procedure carried out by a
Plumis Accredited installer
during which the pump
runs for 20 seconds.
Achieved. The
commissioning procedure
allows the installer to
monitor the ow and
pressure requirements which
can be easily checked at any
time.
Maintenance Annual inspection and
testing by a suitably
qualied contractor.
An annual
recommissioning
procedure to be carried out
by an accredited installer
or the responsible person
trained by the accredited
installer.
Achieved. An identical
level of design redundancy is
included into the Automist
system as would be expected
of a residential sprinkler
system.
Although noted in the table it is worth highlighting Automist should be specied, commissioned and
signed-off by Plumis or a Plumis Accredited Installer only. Each installer has been quality checked and
fully trained by Plumis to ensure that every project is installed to the very highest standards. Each installer
will possess a Plumis Certicate of Approval on successful completion of their training and accreditation
process.

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In this section we detail typical applications for Automist, how it should be specied, and present some
additional points of comparison with conventional sprinklers.
• Providingseparationfromriskareas
The guidance in Approved Document B recommends for studio ats that the kitchen should be
‘remote’ from the entrance door and escape route. Although it is preferable if the cooking facilities
are away from the at entrance the lack of clearly dened guidance on the meaning of ‘remote’ can
lead to inconsistency. Looking at the UK national re statistics and also reference such as BS 5839
Part 6 it is clear that kitchens are the location of over half of all dwelling res, with cooking being
the cause of ignition. In contrast approximately 15% of all re deaths result from res that originate
in kitchens, suggesting that kitchen res tend to occur whilst the occupants are awake and therefore
able to respond at an early stage.
Where differences in interpretation occur Automist can be used to help address concerns over this
issue by reducing the risks associated with the cooking facilities. In this application Automist covers
all occupant types and the suppression will control the re at an early stage, minimising heat and
smoke generation and providing cooling to improve the potential for escape.
• Providingaprotectedrouteoutfromtheloftroomstoanalexitatthegroundoor
after a loft conversion or when creating an open plan arrangement
Approved Document B, Volume 1 proposes sprinklers as a means of protecting the open plan area at
ground level. Given Automist’s effective suppression performance discussed in Appendix A and the
satisfactory installation standards discussed in Section 10 it is proposed that Automist can be used
as an alternative to sprinkler protection to the open-plan area.
In 2010 the NHBC Foundation released a research paper prepared by the BRE on open plan
apartment layouts considering the application of residential sprinklers and LD1 standard re alarm
and detection systems as reasonable measures for enabling open plan apartment layouts (providing
the apartments were with dened limits). These proposals have more recently been adopted in
the draft British Standard BS9991 (the proposed replacement for BS5588 Part 1), amongst a wider
recognition of the potential application of water mist systems in residential design.
Where open plan layouts are proposed, especially conversion projects where retro tting entire
residential sprinkler systems would be prohibitive, Automist provides a viable and effective
alternative.
9 Use of Automist

Page 16 of 27
• Providingadequateprotectionwhenredoorsareeitherremovedordowngraded
In the example of a re engineered solution, where the plans are compliant with Approved
Document B principles, the suppression capabilities of Automist can be used in conjunction with
an analysis of the proposed doors material properties and comparative re and temperature
performance, where the client wished to either use a door which was not re resistance certied or
was inherently non-re rated.
As shown in the BRE re testing (covered in detail in Appendix A) Automist was capable of
maintaining compartment temperatures to around 100oC within the re compartment. Providing
the chosen door performance is capable of maintaining its integrity at temperatures of 100-150oC
and the accommodation room falls within the design parameters for Automist coverage then this
proposal can be justied as achieving an equivalent level of performance.
• Providingcompensatoryprotectionwhenreserviceaccessisextended
Following the recent amendments to Approved Document B, re service vehicle access distances
were reduced to residential buildings. Currently Approved Document B proposes that re service
vehicle access should be achieved to within 45m of the furthest point in the dwelling when
measured from the re appliance parking position. When this guidance cannot be achieved there
is the potential for debate over the most appropriate and practical solutions. Approved Document
B would suggest that dry rising water mains be provided where basic vehicle access is achieved
however this is often disputed by re services on grounds of travel distance, availability of water
supplies and additional time prior to commencing re ghting. It is not uncommon on compact
developments for ideal access to be impossible to achieve and therefore Automist offers reasonable
and cost effective alternative solutions.
When the re service arrive at the scene the re could have been growing for at least 20 to
30minutes (based on the time required for detection, the call to the re service and then the re
service response) which could result in a very large re where re suppression is not present
therefore including efcient re service access arrangements becomes vital. In contrast with
Automist provided to the accommodation rooms the re size and the compartment temperatures
would be greatly reduced and also controlled (as demonstrated in Appendix A). The suppression
effects would largely compensate for less than ideal re access by minimising the extent of re
ghting required, creating relatively stable conditions and increasing the time available for re
ghters to setup prior to commencing operations. As secondary benets the suppression will also
help to improve conditions for escape within the dwelling prior to re service arrival and also assist
with limiting re damage.

Page 17 of 27
Automist design specication guidelines state that a single pump can cover an area of up to 32m2, with
a maximum ceiling height of 5m. Based on Plumis’s experimental data from BRE, spray heads must be
located within 5m line of sight of any possible re location.
10 Specifying Automist
5m
5m
Correct Incorrect

Page 18 of 27
Small potentially blocked or shadowed oor areas shall be permitted on a horizontal plane in compartments
of 64 m2 (two pump units) or less as long as the maximum area of the total contiguous shadowed oor area,
regardless of geometric conguration, does not exceed 2 m2.
Preliminary Automist designs can be recommended by speciers by following these recommendations,
however, Plumis accredited installers are trained to specify, install, commission and maintain the Automist
system. Their early involvement in the project is recommended as they are required to verify installation
proposals, provide critical supporting technical information and also commissioning certicates for project
approval by Building Control or other involved third parties.
5m
5m
Correct Incorrect

Page 19 of 27
Automist should be specied, commissioned and signed-off by Plumis or an Accredited Reseller. Each
reseller is fully trained to ensure that every project is installed to a high standard, receiving a Plumis
Certicate of Accreditation on successful completion of the training.
Automist is an innovative re suppression unit which can be installed as a compensatory measure for
layouts that don’t match the conventional prescriptive guidance from Approved Document B or supporting
guidance for the Regulatory Reform (Fire Safety) Order and the Housing Act.
The Registered Detail RD171 allows assessors to approve Automist with condence for use in open-plan
access rooms, both in ats and in houses with no more than one oor above 4.5m.
11 Conclusions

Page 20 of 27
12 Appendix
12.1 Fire Testing at BRE
In one of the most comprehensive test suites ever run on a mist product at the Building Research
Establishment (BRE), Plumis veried the effectiveness of Automist with live burns in a series of different
scenarios. The test was based on BS EN 1869:1997, DD 8458 1:2010, and the criteria of Scandinavian
SRSA/DSB “Easily installed automatic extinguishing systems”. Critically, Fractional Effective Dosage (FED)
measurements and “free burn” control tests were included to allow a complete and objective assessment.
These tests were run in BRE Global’s Watford (UK) Burn Hall and mimicked both furniture and kitchen
res.
What is Fractional Effective Dosage?
Fractional Effective Dosage (FED) is a calculation method used to predict impacts on re victims as a result
of the “doses” of toxic gases concentration and the temperature exposure during a re. This is detailed by
the method of Prof D.A. Purser and is used to British and European Standards (BS7899-2: 1999: Code of
practice for assessment of hazard to life and health from re. Guidance on methods for the quantication of
hazards to life and health and estimation of time to incapacitation and death in res and ISO TS 13571: Life-
threatening components of re – Guidelines for the estimation of time available for escape using re data,
respectively).
FED has a toxic gas component (FED-Asphyxia) and a temperature component (FED-Heat).
FED Asphyxia: Exposure to a sufcient inhaled dose of asphyxiant gases results in cerebral hypoxia
(insufcient oxygen available to brain tissue), which leads to collapse with loss of consciousness followed
by death if the exposure is prolonged. The inhaled dose of asphyxiant gases increases with re duration
and with the increased concentration of toxic gases with re growth. Consequently, the main objective
from a re protection perspective is to minimize re spread (reducing the concentration rate of increase)
sufciently to avoid loss of consciousness but most importantly death before rescue arrives. In the BRE
tests, the toxic gases considered were carbon monoxide and carbon dioxide, as well as low-oxygen hypoxia.
The dosage of toxic gases is also dependent on rate of air intake. For these tests, it has been assumed that an
occupant was stationary but agitated while in the compartment during a re, resulting in ventilation (VE)
of 15 litres per minute. Using this method, loss of consciousness is expected when the FED of asphyxiant
gases (FEDAG) reaches 1 while death is expected at an FEDAG of approximately 2-3.
FED Heat: The main hazards from a brief exposure to heat during a re are skin pain and burns, followed
by death in severe situations. This depends mainly on the duration of exposure and the temperature
increase during a re so suppression will not only reduce the temperature but also avoid it from increasing.
When FED Heat reaches 1 it is assumed that an occupant will be incapacitated due to pain. Third degree
burns are predicted at an FED of approximately 3. Additionally, for air saturated with water vapour (as in a
water mist fought re), the maximum temperature at which air can be breathed is 60°C.