BS 8313-1997 Accomodation of Building Services in Ducts
BS 8313-1997 Accomodation of Building Services in Ducts
BS 8313-1997 Accomodation of Building Services in Ducts
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Code of practice for |
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Accommodation of |
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building services in |
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ducts |
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Licensed copy:Southbank University, 26/03/2008, Uncontrolled Copy, © BSI
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ICS 91.140.01 |
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NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW
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BS 8313 : 1997
BSI 1997
Amendments issued since publication
First published as CP 413,
March 1951 Amd. No. Date Text affected
Second edition July 1973
Third edition July 1989
Fourth edition July 1997
Contents
Page
Committees responsible Inside front cover
Foreword iii
Code of practice 1
1 Scope 1
2 References 1
3 Definitions 1
4 Exchange of information 2
5 Materials and components 2
6 General 2
7 Restrictions on positioning and combination of services 3
8 Space requirements 6
9 Access 7
Licensed copy:Southbank University, 26/03/2008, Uncontrolled Copy, © BSI
BSI 1997 i
BS 8313 : 1997
Figures
1 Minimum sizes of access openings for passage by persons 7
2 Anthropometric data 8
A.1 Space with limitations due to firm obstacles 20
A.2 Jointing and supporting air ducts without insulation and with a firm
obstacle on one side 20
A.3 Jointing and supporting air ducts without insulation and with a firm
obstacle on two sides 21
A.4 Jointing and supporting air ducts without insulation and with a firm
obstacle on three sides 21
A.5 Jointing and supporting air ducts without insulation and with a firm
obstacle on four sides (obstacle not continuous for more than 1 m) 22
A.6 Jointing and supporting pre-insulated air ducts with a firm obstacle on one
side 22
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A.7 Jointing and supporting pre-insulated air ducts with a firm obstacle on two
sides 23
A.8 Jointing and supporting pre-insulated air ducts with a firm obstacle on
three sides 23
A.9 Jointing and supporting pre-insulated air ducts with a firm obstacle on
four sides (obstacle not continuous for more than 1 m) 24
A.10 Insulation of an air duct in position with a firm obstacle on one side 24
A.11 Insulation of an air duct in position with a firm obstacle on two sides 25
A.12 Insulation of an air duct in position with a firm obstacle on three sides 25
A.13 Insulation of an air duct in position with a firm obstacle on four sides
(obstacle not continuous for more than 1 m) 26
A.14 Examples of installation spaces for flange jointed air ducts 26
A.15 Installation space dimensions A and B for flange jointed air ducts with a
firm obstacle on one side 27
A.16 Installation space dimensions A and B for flange jointed air ducts with a
firm obstacle on two sides 28
A.17 Installation space dimensions A and B for flange jointed air ducts with a
firm obstacle on three sides 29
A.18 Installation space dimensions A and B for flange jointed air ducts with a
firm obstacle on four sides 30
A.19 Examples of installation space for slip jointed air ducts 31
A.20 Installation space dimensions A and B for slip jointed air ducts with a firm
obstacle on one or more sides 32
A.21 e-values 33
A.22 Minimum access allowance e for air ducts insulated in position 34
A.23 Installation space dimensions A and B for air ducts insulated in position
with a firm obstacle on one side 34
A.24 Installation space dimensions A and B for air ducts insulated in position
with a firm obstacle on two sides 35
A.25 Installation space dimensions A and B for air ducts insulated in position
with a firm obstacle on three sides 35
A.26 Installation space dimensions A and B for air ducts insulated in position
with a firm obstacle on four sides 36
B.1 Installation spaces for uninsulated or pre-insulated air ducts 40
B.2 Installation spaces for air ducts insulated after installation 41
Index 44
List of references 47
ii BSI 1997
BS 8313 : 1997
Foreword
This British Standard has been prepared under the direction of the Technical
Committee B/209. It supersedes BS 8313 : 1989, which is withdrawn.
This edition introduces technical changes but it does not reflect a full review or
revision of the document, which will be undertaken in due course.
This code of practice is intended to provide architects, engineers, builders, contractors,
suppliers, specialists, and service engineers with recommendations for the design,
construction, installation and maintenance of ducts in buildings for the
accommodation of services. It also covers ducts attached to the outside of buildings,
suspended flooring and ceiling voids, and cavities which are used for services but not
always referred to as ducts. Annex A gives a detailed method for calculating the
minimum cross-sectional dimensions of space required in service ducts for the
installation and maintenance of thin walled HVAC ducting and annex B provides a
simplified method for doing the same calculation. Annex C draws attention to the
stressful nature and potential hazards associated with working in a confined space and
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annex D lists Acts, bylaws and statutory regulations which relate to the
accommodation and maintenance of building services in ducts.
As a code of practice, this British Standard takes the form of guidance and
recommendations. It should not be quoted as if it were a specification and care should
be taken to ensure that claims of compliance are not misleading. In particular,
attention is drawn to 6.1 and the fact that statutory legislation may impose more
stringent requirements in certain circumstances.
The standard should not be regarded as a substitute for expert advice. The intention is
that it should complement it.
Every fire authority has Fire Prevention Officers who will advise designers, owners and
occupiers and who will welcome liaison with architects and facilities engineers on the
safety aspects of building design. Advice can also be obtained from the Health and
Safety Executive and from local authorities on matters relating to health and safety,
and from Building Control Officers if new buildings or major alterations are involved.
Compliance with a British Standard does not of itself confer immunity
from legal obligations.
Summary of pages
This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to
48, an inside back cover and a back cover.
iv
blank
BS 8313 : 1997
Code of practice
buildings.
air or objects which, together with its frame and
This standard does not cover the design and furniture as installed in a building, is intended when
construction of air or refuse ducts, nor those with closed to resist the passage of fire and/or gaseous
`heart units', `packaged plumbing' or `service walls', products of combustion and is capable of meeting
although parts of it are relevant to them. specified performance criteria to those ends.
This standard does not cover spaces intended mainly
3.7 fire resistance
for purposes other than the accommodation of
services, nor with plant areas such as boiler and Ability of a component or construction of a building
calorifier rooms or gas storage areas. to satisfy for a stated period of time some or all of
the criteria specified in BS 476 : Part 4 and BS 476 :
The piping of radioactive substances and the
Part 24, covering stability, integrity and insulation.
specialist requirements for piping cryogenic liquids
are generally outside the scope of this standard. 3.8 fire stop
Seal provided to close an imperfection of fit between
elements, components or construction in a building,
2 References or in any joint, so as to restrict penetration of smoke
2.1 Normative references and flame through that imperfection or joint.
This standard incorporates, by dated or undated 3.9 firm obstacle
reference, provisions from other publications. These Any obstacle that will interfere with the installation,
normative references are made at the appropriate dismantling or maintenance of a service.
places in the text and the cited publications are
listed on page 47. For dated references, only the 3.10 flash point
edition cited applies; any subsequent amendments to Lowest temperature at which vapour from oil, etc.
or revisions of the cited publication apply to this can be ignited by an external source.
standard only when incorporated in the reference by 3.11 installation space
amendment or revision. For undated references, the Recommended minimum space necessary for the
latest edition of the cited publication applies, installation and maintenance of one or more services
together with any amendments. where access is limited by a firm obstacle. It is
2.2 Informative references expressed as a rectangular envelope at right angles
to and at any point along a run of services. It
This standard refers to other publications that
includes allowances for supports, thermal and sound
provide information or guidance. Editions of these
insulation, and safety margins.
publications current at the time of issue of this
standard are listed on page 48, but reference should 3.12 material of limited combustibility
be made to the latest editions. Material that conforms to any of the specifications
given for materials of limited combustibility in the
Approved Document published in connection with
3 Definitions B2/B3/B4 of the Building Regulations 1991[1].
For the purposes of this British Standard the
3.13 nominal size
definitions given in BS 6100 apply, together with the
following. Size used in the designation of appliance or
component.
3.1 duct
3.14 protected shaft
Space formed for the passage of cables, pipes, etc.
Stairway, lift, escalator, chute, duct, or other shaft
3.2 service duct which enables persons, objects or air to pass from
Duct that allows working space. one compartment to another.
BSI 1997 1
BS 8313 : 1997
co-ordination of the services within them. imposed by the Health and Safety at Work etc.
Act 1974 [2], the Asbestos (Licensing)
4.2 Consultation and co-ordination Regulations 1983 [3] and the Asbestos (Prohibition)
The necessary consultation and co-ordination should Regulations 1992 [4] and the Control of Asbestos at
be carried out and particular attention should be Work Regulations 1987 [5]. Guidance on work
paid to the following points: involving exposure or potential exposure to
a) brief from client; asbestos is found in the Health and Safety
b) system for ensuring that drawings and Executive (HSE) publications EH10 [6], L27 [7] and
specifications reach those who need them; L28 [8]. Components should be free of sharp edges
and projecting spikes, and should be easy to
c) system for spatial co-ordination; assemble.
d) project programme; g) Resistance to fire: combustibility, fire resistance
e) consultation with planning, building regulations and resistance to fire spread of the completed duct
and fire authorities; and its contents should always be assessed as part
f) consultation with gas, electricity, water, of the overall fire engineering design of the
sewerage and telecommunications authorities; building.
g) consultation with insurers; h) Resistance to pests: materials should not be
h) consultation with suppliers of special services liable to attack by insects, fungi or vermin or
such as industrial and medical gases (or other should be protected by suitable preservatives.
authoritative source); i) Cost and availability: cost and availability affect
i) operation and maintenance instructions; both construction and maintenance.
j) Ease of installation and maintenance. Materials
j) the possibility of increased future requirements
and components should be chosen taking into
owing to further development within or adjacent
consideration the labour, tools and equipment
to the project should be considered.
likely to be available for installation and
NOTE. Lack of systematic advance planning of services can result
in delays and expensive alterations.
maintenance, including cleaning. If installation and
maintenance is easy, it is more likely to be done
properly.
5 Materials and components
5.1 British Standards 6 General
Materials and components should conform to 6.1 Statutory provisions
relevant British Standards.
It is essential that designers of buildings, service
5.2 Choice of materials and components installations and ducts are aware that there is a wide
Factors that should be considered when duct range of Acts, Regulations and Bylaws covering such
materials and components are selected are as work in England and Wales, Scotland and Northern
follows, not necessarily in order of importance. Ireland (see annex D). It is their duty to ensure
compliance with the relevant requirements.
a) Mechanical properties: strength, elasticity,
ductility and mass. 6.2 Principles of general arrangement
b) Electrical properties: electrical conductivity and Most projects require that services be enclosed for
electrical insulating strength (of an insulator). part of their route through the building or buildings.
NOTE. Insulating materials may create the risk of electrostatic Services may be enclosed in a variety of types of
discharges. space.
2 BSI 1997
BS 8313 : 1997
Service ducts may be formed as part of the building Openings for services are weak points in the fire
structure or as non load bearing elements. compartmentation of a building. Their number and
Service ducts may be inside a building or attached to size should be minimized, and close attention paid to
its outside along their length. their detail design.
The complexity of the system of service ducts and Consideration should be given to routing of services
associated spaces depends on the size of the project to avoid escape routes, hazardous areas and clean
and the density of the services within it. The system areas.
should always be considered as a whole. Every effort The necessary precautions should be taken in design
should be made to simplify it, in order to ease of the services to provide adequate control of noise
design, construction and maintenance. transmission between different parts of the building.
The starting point for the general arrangement of the Suitable planning of the duct position may reduce
duct system should be a sketch or sketches showing noise transmission. Structural precautions to reduce
the proposed service ducts, which services they are transmission include adequate mass of the duct
intended to contain and the approximate capacities. walls, the sealing of gaps to avoid transmission via
The point of entry for services should normally be air paths, adequately designed access panels, which
on that side of the building nearest to the street in should be kept to a minimum in size and number,
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which the mains are installed. and, if necessary, the introduction of barriers at floor
levels in vertical ducts. See BS 8233.
It is often appropriate to build up the duct system
from the following three types of ducts: 6.4 Thermal insulation
a) horizontal main ducts; Hot or cold pipes and air ducts should be insulated
in accordance with BS 5422 and BS 5970. Barriers
b) vertical main ducts; across the duct or thermal insulation of the duct
c) secondary ducts. walls may be necessary to prevent damage to the
The designer may use some other system if building or contents or discomfort to the occupants
appropriate. (see also 13.2.1).
In multi-storey buildings, a smaller number of large
vertical ducts with adequate provision for horizontal 7 Restrictions on positioning and
distribution above ceiling level and below structural
members, or in service floors, will generally give the
combination of services
most flexible arrangement. 7.1 General
A larger number of small vertical ducts with ceiling 7.1.1 The consequences of the failure of the
spaces for horizontal distribution as necessary will services by themselves or in conjunction with other
generally be less flexible. The omission of space services should be considered and if this could
above ceilings generally produces the least flexible introduce a hazard the services should be
arrangement. segregated.
In single-storey buildings, accommodation for NOTE. Where this standard recommends certain services to be
accommodated in separate ducts and the separate ducts are
services may be needed below floor level, or above adjacent, the division between the ducts should afford adequate
ceiling level, or both. separation and fire resistance consistent with the hazards
External ducts should be weather resistant. involved.
Underground ducts should be resistant to the entry 7.1.2 Hazardous materials such as flammable,
of ground water and to chemical attack by the soil, oxidizing, toxic or corrosive gases or liquids should
and should be able to accommodate soil movement. only be run in ducts when there is no safe practical
6.3 Interaction of duct layout with building alternative.
design Gas pipes may be run in ducts provided the
The spaces required for services should be recommendations of 7.2.3 are applied. Where other
incorporated in the building design from the earliest hazardous materials have to be in pipes in ducts,
sketches. If sufficient space is not allowed in the then the recommendations of 7.2.2 to 7.2.6 should
initial concept it can be extremely difficult to apply.
achieve a satisfactory solution in the completed 7.1.3 Services not associated with lifts should not
project. Information on space allowances for ducts is be run in lift wells.
given in clause 8. 7.1.4 Services should only be run in air ducts if the
Close co-operation between the designers of the following points are taken fully into account at the
services and of the building is essential. Particular design stage of the air ducts and the system of which
attention should be given to the design of service they are part.
entry and exit points, to ensure that the building is a) The consequences of gases, vapours or liquids
not weakened and that services are protected from escaping from piped services and being
differential movement. It is sometimes necessary to transported around the building should be
make holes in load-bearing walls or floors for the considered. In no case should services carrying
passage of services, to resite beams or columns or to toxic or flammable substances be routed through
re-route services to avoid them. air ducts.
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BS 8313 : 1997
b) Services within an air duct will increase its Air ducts conveying clean air for ventilation, heating
resistance to air flow and make it more difficult to or air conditioning should be insulated, if necessary,
clean the duct. Service penetrations through the to prevent condensation, a change in air temperature
duct wall may increase air leakage. Both of these or extremes of temperature in the service duct.
factors may increase the duct size and, in the case Air ducts conveying polluted air from fume
of mechanical systems, the fan size and power cupboards, industrial processes, etc. should be
required to achieve specified air flow rates at the designed and sited after consideration of the
terminals. particular hazards involved. They should be
7.1.5 Cavities in walls and partitions should not be segregated from other services, if appropriate.
used as service ducts unless suitable for that All extract ducts from fume cupboards should be
purpose. Routing of flammable, oxidizing, toxic or under negative pressure where they run through
corrosive services through such cavities in structural buildings.
walls should be avoided where practicable, but, if Air ducts serving parts of a building or appliances
necessary, special precautions should be taken. considered to be special risks should, where
Some points that should be considered are as necessary, be independent of each other and of any
follows: air ducts serving other parts of the building. The
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a) the requirements of the Gas Safety possibility of fire in extract ducts from frying areas
Regulations 1972 [9] and the Gas Safety in kitchens should be considered.
(Installation and Use) Regulations 1994 [10]; Where practical, flue pipes should not be run in the
b) services should take the shortest practical route same duct as other services. Where this is not
through the cavity; practicable, they should be insulated to prevent
c) in the case of flammable, oxidizing, toxic and excessive heat loss and high temperatures where
corrosive services, use of high integrity pipework, these could present a hazard. Particular attention
e.g. avoiding joints within the cavity, etc. and should be given to maintaining any fire separation.
secondary sleeving as appropriate (see 13.5.7d)3)); Compressed air pipes do not normally present a
d) the dispersal of any leakage in the cavity; hazard to other installations although leaking
e) provision of access for inspection and compressed air may cause injury to personnel.
maintenance of the service within the cavity; Vacuum pipes do not normally present a hazard to
f) the effect on the fire resistance of the wall; other installations. Suitable precautions should be
taken if they are run in the same duct as any service
g) the effect on the acoustic integrity of the wall.
conveying flammable, oxidizing or corrosive
7.1.6 The effects of leakage of services and the substances.
effect of each service on neighbouring services Electrical installations should conform to BS 7671 :
should be considered. For example, water and other 1992. Telecommunications installations should be in
fluids can cause damage by corrosion and solvent accordance with BS 6701. In particular, the following
action. Hot fluids can cause damage by overheating. precautions should be taken.
A jet of fluid escaping from a pressurized service can
a) Cables, conduits, trunking and cable trays
cause damage by force of impact. The contents of
should be separated from pipes or other services
some pipes may be poisonous or infectious. Pipes
by at least 25 mm, and more for large services.
conveying gases that are heavier than air should be
Alternatively, adjacent metallic surfaces should be
placed at the top of horizontal ducts and those
electrically insulated.
conveying gases that are lighter than air should be
placed at the bottom, so that escaping gas will be b) Cables and accessories should be selected and
diluted as much as possible. installed such that under reasonably foreseeable
fault conditions they will not create a hazard
7.2 Restrictions for particular services either alone or in conjunction with other services.
7.2.1 Hot water, steam and condensate pipes should c) Installations should be protected from
be insulated to prevent excessive heat loss and high overheating.
temperatures within the duct. Hot pipes should not d) Telecommunications installations should be
be run adjacent to chilled water services, plastics protected from interference from electrical
drainage systems or electrical or telecommunications installations.
cables, regardless of insulation. Condensate pipes
e) Discharge pipes and drains should be
and screwed joints in steam and pressurized hot
positioned considering the need for access for
water pipes are particularly liable to corrosion.
rodding and the likelihood of escape of liquid
Cold, drinking and chilled water pipes should be during this operation. In horizontal ducts they
insulated to prevent condensation and/or a rise in should, if possible, be positioned below all other
water temperature. (See also 10.4.) services.
NOTE. Pipes containing fire fighting water do not normally require
insulation to prevent condensation, as the water is stationary.
4 BSI 1997
BS 8313 : 1997
7.2.2 For the purposes of this standard, gas, vapour 7.2.3 Pipes conveying town gas, natural gas and
and liquid pipelines are classified into groups liquefied petroleum gases (LPG) should be installed
depending on the major risk associated with the in ducts according to the relevant requirements of
pipeline contents: BS 6891, and BS 5482: Part 1, the Liquefied Petroleum
a) Group 1: flammable. Flammable gases, Gas Association (LPGA) Code of practice No. 22 [11]
e.g. natural gas, hydrogen, propane, and butane, and the Institution of Gas Engineers (IGE)
flammable liquids, highly flammable liquids, and publications IGE/UP/2 [12] and IGE/TD/4 [13].
higher flash point liquids such as oils; 7.2.4 Pipes conveying flammable gases or
b) Group 2: oxidizing. For example, oxygen, flammable liquids (group 1) should only be run in
nitrous oxide and oxygen mixtures; ducts if the following precautions are taken.
c) Group 3: toxic or corrosive. For example, a) Pipes should be of non combustible material
ammonia, chlorine and certain laboratory wastes. with a melting point not lower than 800 ÊC but
d) Group 4: hot services, which may scald or burn. should not be of asbestos cement.
For example, steam, high temperature hot water b) Ducts should be well ventilated (see clause 12)
(HTHW) and medium temperature hot water or, by some other suitable means, it should be
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BSI 1997 5
BS 8313 : 1997
precautions are taken to ensure that dangerous ducts is given in annexes A and B.
substances cannot be transmitted through the 8.3 Maintenance
ventilation system.
8.3.1 Sufficient space should be provided for the
7.2.7 Pipes covering refrigerants should conform to operation, inspection and repair of valves, dampers,
BS 4434. Pipes conveying flammable, oxidizing, toxic cleaning points, expansion joints and other fittings,
or corrosive refrigerants should, in addition, be in and the cleaning and painting, if applicable, of the
accordance with 7.2.2 to 7.2.6, as appropriate. inside of the duct and the services within it.
7.2.8 Pressurized pneumatic pipelines for conveying Additional spacing will be needed for access for
flammable dusts or powders should not be run in tools and work on pipes and ducts. This may be in
ducts. Where this is unavoidable, the severe risk of excess of 250 mm for a typical spanner.
fire and the consequence of a leakage should be
8.3.2 Careful consideration should be given to what
taken into account.
degree of demolition of the duct and disruption of
other services will be acceptable when a service is to
8 Space requirements be maintained or modified. Services should
preferably be arranged so that it is possible to
8.1 Space allowances for ducts at the outline remove one without disturbing the others.
design stage
8.4 Future requirements
8.1.1 Space for air ducts
Adequate space should be provided initially to allow
The installation space required for supply air ducts for the renewal of services. Most building structures
for low velocity systems can be estimated by can be expected to last much longer than the
dividing the required air volume flow rate by a services.
velocity of 4 m/s. Return air ducts will normally
require as much space as supply air ducts. 8.5 Critical points
8.1.2 Vertical ducts for piped and electrical The size of a duct is usually determined by space
services requirements at critical points such as changes of
direction, branches or crossings rather than on
The installation space required for vertical ducts for straight runs.
piped and electrical services on each floor of a
multi-storey building is usually between 1 m2 8.6 Flanges and insulation
and 2 m2 for each 5000 m3 of building volume. The size of a pipe or air duct including connections
8.1.3 Space for additions and alterations and/or insulation can be much greater than its
nominal size.
Between 10 % and 15 % extra space should normally
be allowed for future additions and alterations. 8.7 Separation of services
8.1.4 Depth of ceiling voids Extra space may need to be allowed for separation
of incompatible services (see clause 7).
Ceiling voids should have a minimum depth
of 500 mm free of structural members. To avoid 8.8 Modular co-ordination
excessively deep ceiling voids and to ease balancing If a modular system of dimensional co-ordination is
of systems, each vertical service duct should serve a being used for the project, the service ducts and
maximum area of about 1000 m2. their contents should be dimensioned and positioned
within this system.
6 BSI 1997
BS 8313 : 1997
BSI 1997 7
BS 8313 : 1997
a) Prone
b) Kneel
c) Crawl
d) Squat
e) Stoop g) Passageway
All dimensions are in millimetres.
8 BSI 1997
BS 8313 : 1997
Licensed copy:Southbank University, 26/03/2008, Uncontrolled Copy, © BSI
Ladder width 380 min. 450 optimum Width for one man 600 to 750
Distance between side walls 600 min. Width for two men 1100 min.
Rung distance c 225 to 250 Riser b 184 optimum
Rung diameter d 20 to 40 Tread c 240
(h) Ladder (i) Steps
Width 530 to 600 with handrails Width 750 min. to 1100 optimum
600 min. between side walls (k) Ramp
Riser b 250 maximum
Tread width c 80 to 150
(j) Inclined ladder
All dimensions are in millimetres.
Figure 2. Anthropometric data (concluded)
Doors and covers should be hinged or completely Continuous trench covers generally require
removable. Sliding doors should not be used. All individual adjustment during installation to ensure
doors should open outwards from the duct interior. accurate alignment of the surfaces with adjacent
Hinged hatch covers in floors should open floor surfaces and to eliminate any tendency to rock
through 180 Ê or be provided with a self-locking upon the bearing points. It is, therefore important
device to hold the hatch open. Doors of ducts that that individual sections of trench covers be
are large enough to be entered should be openable numbered or marked to ensure that they are placed
in correct sequence.
from the inside of the duct.
9.7 Security
Heavy trench covers do not usually require securing.
Special procedures or devices controlling the use of
Other access covers and doors should preferably be doors and access covers may be needed, particularly
secured by budget locks (see 3.16). if a hazard may arise from unauthorized use.
BSI 1997 9
BS 8313 : 1997
10 Protection of services in ducts warning pipe or other suitable means should indicate
that liquid has escaped within or has entered the
10.1 Mechanical damage duct. Precautions should be taken to maintain trap
Services should be protected from accidental and seals to prevent the entry of rodents, for instance by
malicious damage by suitable positioning or connecting the discharge from a sanitary appliance
enclosure. to the trap. Precautions should also be taken against
10.2 Condensation back flow drains into underground ducts.
Condensation should be prevented by suitable choice 11.3 Collection in holding tank
of insulation, ventilation and heating. If the water authority does not accept discharge to
10.3 Corrosion the building drainage system, etc., drains from ducts
Corrosion should be minimized by choice of suitable should discharge to a holding tank. The capacity of
materials and combinations of materials, by keeping the tank should be chosen in relation to the amount
ducts and services dry and by application of suitable of liquid likely to escape from a failed service.
paint or other protective coatings. Relevant Provision should be made for emptying the holding
information is given in BS 5493 and PD 6484. tank to a disposal contractor's vehicle or other
suitable recipient. An alarm should indicate that
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10.4 Frost
liquid has entered the tank, so that the cause can be
Services liable to frost damage should be positioned established and remedied.
in frost-free places where possible. If this is not
possible, they should be protected by insulation 11.4 Retention within the duct
and/or heating. The latter should be thermostatically If there is a significant probability of a liquid service
controlled. Particular care should be taken when leaking and causing damage but it is impractical to
water services are run in ventilated ducts. provide drainage, the duct should be made
watertight and arrangements made for removing and
10.5 Thermal expansion
disposing of liquid retained in the duct after a leak.
Provision should be made for thermal expansion of An alarm should indicate that there is liquid in the
services without imposing excessive loads on the duct, so that the cause can be established and
structure, fixings or services. remedied.
10.6 Differential movement 11.5 Watertightness
It is common for services to have to accommodate Ducts below ground level which may be subject to
differential movement, particularly, but not only, at external water pressure should be watertight.
service entry and exit points. Services should (See CP 102.)
therefore be designed so that they can accommodate
the expected movement without damage. Advice on
how much movement can occur may need to be 12 Ventilation of service ducts
sought. 12.1 General
10.7 Provision of adequate support It is recommended that building service ducts should
In selecting the method of supporting services, be ventilated regardless of the services they contain.
provision should be made for the overall dimensions Ventilation for persons within ducts is covered
of the services where these are to be thermally in 12.2, for the control of hazardous leaks in 12.3,
insulated, and for the preservation of any and for the control of environmental effects,
moisture-proof layer. e.g. condensation or overheating in 12.4. Satisfying
Typical fixings and supports are specified in BS 3974 the single largest requirement should be satisfactory
and BS 5572. in all cases.
The provision for ventilation should be so designed
11 Drainage of service ducts as not to decrease the fire safety of the building.
Ventilation openings provided in accordance
11.1 General with 12.1 to 12.4 should, where necessary, because a
Drainage should be provided in ducts to dispose of fire resisting division is passed, be fitted with
liquids from leakage or infiltration. devices, e.g. fire resisting doors or dampers, that will
Special consideration should be given to the close automatically in case of fire. Consideration
drainage of flammable, toxic or corrosive liquids. should be given to the provision of indicators to
11.2 Discharge to building drainage show whether the device is open or closed.
system, etc. NOTE. Ducts with a cross-sectional area of less than 0.05 m2
which convey only services in the following list need not be
Drains from ducts should discharge to the building ventilated other than as required in 12.2 or to prevent overheating:
drainage system, a soakaway or watercourse, etc., if a) ventilation, air conditioning, warm air heating;
this is acceptable to the water authority. If sufficient b) drainage in houses, offices and shops, except food shops;
fall is not available, a sump with an automatic pump c) electric power and telecommunications;
and high level alarm should be provided. A warning d) substances of groups 4 and 6 (see 7.2.2);
pipe or other suitable means should be provided. A e) vacuum pipelines.
10 BSI 1997
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12.2 Ventilation for persons Table 1. Free area of ventilation opening for
Work carried out in confined spaces is potentially dispersal of small leaks
hazardous and guidance on the precautions to be Cross-sectional area of duct Minimum free area of each
taken is given in annex C. m2 opening
Ventilation for persons within ducts may be achieved Not more than 0.05 Cross-sectional area
either by permanent means or by providing of duct
ventilation prior to and during occupation.
More than 0.05 but not 0.05 m2
The ventilation applied should be capable of more than 7.5
providing respirable air for persons whilst working.
In some instances additional air may be required to More than 7.5 1/150th of area of duct
cater for the work being undertaken, e.g. removal of 12.3.2 Duct ventilation openings should lead to safe
heat or dilution of welding fumes. places, preferably the open air. Ducts contained
BS 5925 provides information on the quantities of air solely within a room or an occupied space and not
required. (See also Health and Safety Executive containing group 3 services may be ventilated within
Guidance Note EH22 [14].) that room provided that the room is ventilated (see
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BSI 1997 11
BS 8313 : 1997
length.
13.1.2 Unless suitable precautions are taken, service
ducts may be: 13.2.6 If flammable or oxidizing services are to be
a) a place where fire starts; installed in a ceiling void or floor void, either the
b) a place where fire grows undetected; services should be enclosed in separate duct(s) or
c) a place where persons become trapped; pipe sleeve(s) within the void, or the void should be
considered as a duct and the necessary ventilation
d) a route for the spread of fire and smoke;
provided.
e) a place where fire is difficult to extinguish.
If group 1, 2 or 3 services are to be installed in a
13.2 Prevention of fire ceiling or floor void they should be enclosed in a
13.2.1 The location and construction of services duct which is ventilated to a safe position.
and ducts within buildings should take into account If the services are enclosed in a separate duct or
the fire hazards to the services from fires which can pipe sleeve within the void, the duct(s) or pipe
occur in the building or in the duct, and the hazards sleeve(s) should be sealed from the void and should
to the building from a major failure of the services. be in accordance with this standard. If the services
In some special cases it may be necessary to provide are not enclosed within a separate duct or pipe
liquid or gas monitoring or explosion reliefs within sleeve within the void, the void should be considered
the duct. to be a service duct.
13.2.2 If combustible materials are considered for
use within or as part of a service duct, the extent to 13.2.7 The following factors should be carefully
which they will increase the fire loading, the considered when locating services in a separate duct
necessary provision of cavity barriers and the within a void:
production of smoke and toxic gases should be a) ventilation of the void;
carefully assessed. Careful consideration should be b) provision of cavity barriers;
given to the potential fire and smoke hazard inherent c) access to services.
in combustible insulation. (See BS 5422 and
BS 5970.) 13.3 Detection and alarm of fire
13.2.3 Ducts to which access is provided should be 13.3.1 Where ducts are large enough for passage of
designed to be cleanable (see 19.3). Accumulations persons, provision should be made for giving alarm
of rubbish, dust or grease can easily be ignited. of fire.
Particular care should be taken that insulation does
not become contaminated by flammable liquids. (See 13.3.2 If the building has a fire alarm system, the
BS 5422 and BS 5970.) alarm sounders should be audible within such ducts
13.2.4 Sources of ignition should be avoided where and manual call points should be situated inside, and
possible. Smoking should be prohibited in service adjacent to, each exit from the duct.
ducts. Suitable precautions should be taken when 13.3.3 If the building has a fire detection system,
operations involving heat, such as soldering and consideration should be given to such system being
welding, are to be carried out inside ducts (see extended into service ducts of whatever size.
Health and Safety Executive Guidance Notes
EH 54 [18] and EH 55 [19]. In high fire risk areas, 13.3.4 Any fire alarm or fire detection and alarm
sparks from power or hand tools are dangerous. system should be in accordance with BS 5839 :
Heat should not be applied to pipes or plant that has Part 1.
contained flammable substances unless it is safe to
do so (see also 19.2).
12 BSI 1997
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13.5.10 Where a duct is contained wholly within 13.6.3 Major service ducts and important features,
one fire compartment, it will not normally require a such as ventilators and gas isolating valves should be
fire resisting enclosure since the possibility of fire shown on the drawings available to the fire service.
spread to another fire compartment via the duct will
not exist. There may be a considerable hazard where 13.6.4 Portable fire extinguishers, hose reels,
small areas of high fire risk such as kitchens or sprinklers and fire extinguishing gas systems should
stores are included in the same fire compartment as be provided in service ducts as appropriate.
sleeping accommodation. In these cases ducts are Any total flooding or automatic fire extinguishers
normally horizontal, and the risk is greater if they mounted in ducts should be in accordance with
are at a high level where they may be subjected to BS 5306 : Part 0, and BS 7273 : Part 2. Further
the worst conditions of flame and heat from a fire. In information is given in Health and Safety Executive
such circumstances, consideration should be given to Guidance Note GS16 [21]. Particular attention should
the duct enclosures, including any access or be paid to the safety of persons within service ducts.
inspection panels in the high fire risk areas, being
fire resisting. 14 Other safety precautions
A fire resisting suspended ceiling does not
14.1 General
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14 BSI 1997
BS 8313 : 1997
Pipelines or services within the ducts should be Lights should be controlled by switches placed at a
suitably insulated and protected to avoid uniform height and at regular intervals. Switches
endangering personnel. Step irons and handrails should always be provided at access points.
should not be in contact with hot pipes. Consideration should be given to the provisions of
Unexpected obstructions or projections by the duct emergency lighting, which should be actuated
or by the services and equipment within should be automatically when the normal lighting fails, or at
limited by careful design and installation. least to placing alternative lamps on two different
Services and equipment should be arranged neatly circuits.
within ducts and should be readily accessible for Explosion protected or waterproof fittings and
maintenance. switches should be used where appropriate
(See BS 5345 : Parts 1 and 2.)
14.4 Protection against falls
It may be necessary to take special precautions 14.7 Equipotential bonding
against the possibility of personnel falling within All simultaneously accessible extraneous and/or
ducts. exposed conductive parts should meet the
No sudden drop should occur over the threshold of requirements of BS 7671.
Licensed copy:Southbank University, 26/03/2008, Uncontrolled Copy, © BSI
an entrance to a duct. If the floor level of the duct is 14.8 Alarm systems
below that of the floor outside, the level of the latter
where possible should be continued through the Suitable alarm systems should be provided if the
threshold to give a platform of minimum recommendations of clause 13 do not ensure safety.
dimensions 750 mm by 750 mm. 14.9 Means of escape
Where a platform cannot be provided, the entrance Suitable means of escape should be provided if the
should be fitted with a guard rail and sill when a recommendations of clause 13 do not ensure safety.
difference in levels occurs over the threshold. Access
openings to under-floor ducts should be protected by
temporary guard rails when open. 15 Service entries and exits
Platforms and staircases within ducts should be 15.1 The following general principles should be
fitted with handrailing 1200 mm high with a midrail observed in the design of service entries and exits.
and toeboard, and an entrance to a stair or ladder a) The service should be supported in such a way
from a platform should be fitted with a safety bar. that differential movement is accommodated or
Suitable fixed ladders, stairs, steps or ramps should prevented;
be provided in vertical ducts or where there is a b) The building and its foundations should not be
change in floor level in a horizontal duct. weakened;
Recommended dimensions for these can be found in
c) The service should be sleeved where it passes
the annexes.
through the building structure;
Fixed ladders should conform to BS 4211. As an
d) The space between the service and the sleeve
alternative to the provision of safety cages as
should be sealed at the point of entry with a non
specified in BS 4211, other suitable means of
hardening plastic material to prevent the passage
providing safety on ladders can be employed,
of water, gas and vermin. (See BS 6213.)
e.g. suitable systems for use with safety belts, which
Consideration may be given to using cable glands
help in the release of a person who has collapsed.
or cable transits as an alternative, where
In vertical ducts, anchors for attaching the safety line applicable;
of a harness should be provided on platforms and in
e) The service should pass through or under the
the side of the duct at intervals of not more
building structure by the shortest practical route.
than 2 m. Anchors should conform to BS 5845, and
safety belts or harnesses should conform to 15.2 The design of service entries and exits should
BS EN 354, BS EN 358, BS EN 361, BS EN 365 and be agreed with the utilities as early as possible.
BS 2830. Advice on the design of service entries and exits can
14.5 Electrical power be found in the following publications:
The provision of electrical power within ducts is not a) gas pipes: IGE publication IGE/UP/2 [12];
normally necessary, however, where needed it is b) telephone, telegraph and data communication:
important to consider the problems of high voltages BS 6701;
and of trailing leads. c) water supply: BS 6700.
14.6 Lighting
A lighting installation should be provided within
ducts large enough to be entered, particularly at
access points.
BSI 1997 15
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16 BSI 1997
BS 8313 : 1997
be readily available. (See BS 5306: Part 0). allowed to accumulate, particularly through
maintenance activities. Ducts should be cleaned as
18 Inspection and testing necessary.
The cleaning of a duct after any form of hazardous
18.1 Inspection should be maintained throughout contamination is a job for specialists.
the period of construction, to ensure that work has
been done correctly and has not been subsequently Regular inspection should be made for the detection
damaged. of vermin and any necessary measures taken for
disinfestation.
18.2 At completion, the cleaned ducts should be Consideration should be given to repainting ferrous
thoroughly inspected and tested. Some points that pipe fixings and other iron work under a planned
should be checked are listed below: maintenance system for protection against corrosion
a) duct ventilators and any associated fire where adverse site conditions are anticipated. For
dampers; precautions in spraying of highly flammable liquid,
b) duct drainage; reference should be made to Health and Safety
c) duct lighting; Executive Guidance Note EH9 [25].
d) alarms, telephones, etc.; 19.4 Fire safety
e) marking; Before any works of maintenance are carried out,
f) fit and lubrication of doors, hatchways, access consideration should be given to the extent of any
panels; fire hazards involved, and the effect of any fire on
the occupants or operation of the building.
g) fire extinguishing equipment; Appropriate precautionary measures should be taken
h) acceptance certificates; where necessary, for example by temporarily
i) drawing showing location of isolators or relocating occupants who may be put at risk should
isolating valves. a fire start. All reasonable precautions should be
taken to avoid the outbreak of fire. Smoking should
be prohibited in ducts and `no smoking' rules
19 Maintenance applicable in other areas of the building should be
NOTE. See also BS 8210. observed by maintenance workers. It is essential that
fire escape routes are kept unobstructed. A portable
19.1 Operation and maintenance instructions
fire extinguisher should be readily available. See
Operation and maintenance instructions should be also 17.6.
supplied, containing complete sets of `as-fitted'
drawings and specifications, instruction manuals for
equipment, etc.
19.2 Routine inspections and maintenance
work
Accessible ducts and services should be inspected at
regular intervals. Records of the inspections and of
any work done should be kept and signed as part of
a policy of planned maintenance.
BSI 1997 17
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Annexes
18 BSI 1997
BS 8313 : 1997
or other requirements. This in turn depends on the are applicable to rectangular air ducts of dimensions a
dimensions of the air duct and the reach of the and b, but can be used also for circular air ducts by
workman with the tools or materials required. using the A and B values where a = b (indicated by a
Care should be taken to provide sufficient access at diagonal line). The shaded areas represent the
any face from which it is necessary to reach an recommended standard ventilation duct sizes given in
adjacent face. Eurovent Document 2/3 [26].
In the case of air ducts insulated in position, the A.7.4 Typical methods used for insulating air ducts in
installation space should be calculated using the situ are as follows.
formulae for either f or e values, whichever gives the a) Method 1. Insulating with rigid slabs, for example
greater space requirement. resin bonded mineral wool, fastened by thin steel
When a face of the air duct does not face a firm bands or the like. Without protective covering. (One
obstacle, a minimum notional space allowance operation.)
of 100 mm or t + 50 mm, whichever is greater, should b) Method 2. Insulating with soft, flexible materials
be provided which, together with the adjacent free such as mats of mineral wool, with or without
space, gives space for a workman's whole body. A netting reinforcement and metallic facing, wrapped
casing, which should be demountable for maintenance around the air duct and sewed or clipped in
purposes, may be installed at the boundary of this position. Without protective covering. (One
notional space. The designer should preserve the operation.)
adjacent free space. c) Method 3. Insulating as methods 1 or 2, but with
The types of calculation of installation spaces for protective covering, for example sheet-metal. (Two
common methods of jointing, supporting and insulation operations, first insulating, and then covering.)
are given in A.7, which also includes tables of
dimensions for the installation spaces related to A.7.5 Figure A.21 and tables A.5 and A.6 show
standard air duct dimensions. examples of e-values for use in calculation of
dimensions A and B for insulating flange jointed and
A.6 Calculation of installation space dimensions slip jointed air ducts with firm obstacles on one or
for air ducts more sides of the duct. Appropriate e-values are given
A.6.1 Figures A.2 to A.5 illustrate calculations for in figure A.22 and table A.7. Minimum installation space
jointing and supporting air ducts without insulation. dimensions A and B are given in figures A.23 to A.26
and corresponding values of n are given in tables A.8
A.6.2 Figures A.6 to A.9 illustrate calculations for to A.11.
jointing and supporting pre-insulated air ducts.
A.7.6 For air ducts pre-insulated externally, minimum
A.6.3 Figures A.10 to A.13 illustrate calculations for installation space dimensions A and B are as given in
insulation of an air duct in position. figures A.15 to A.18 with (2t 2 100) added.
A.6.4 For circular air ducts, d should be substituted For air ducts pre-insulated internally, minimum
for both a and b in the formulae given in figures A.2 installation space dimensions A and B are as given in
to A.13. figures A.15 to A.18, for flange joints, or as in
figure A.20, for slip joints.
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20 BSI 1997
BS 8313 : 1997
B = b + fa1 + 100
All dimensions are in millimetres.
BSI 1997 21
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A = a +fb1 + fb2
B = b + fa1 + fa2
All dimensions are in millimetres.
22 BSI 1997
BS 8313 : 1997
B = b + fa1 + (t + 50)*
All dimensions are in millimetres.
* If (t + 50) < 100, insert 100 (see A.5).
BSI 1997 23
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24 BSI 1997
BS 8313 : 1997
B = b + ea1 + (t + 50)*
All dimensions are in millimetres.
* If (t + 50) < 100, insert 100 (see A.5).
BSI 1997 25
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A = a + eb1 + eb2
B = b + ea1 + ea2
All dimensions are in millimetres.
Figure A.13 Insulation of an air duct in position with a firm
obstacle on four sides (obstacle not continuous for more
than 1 m)
26 BSI 1997
BS 8313 : 1997
,,,,,,,,
a < 1000
a
b 100 150 200 250 300 400 500 600 800 1000 B
,,,,,,,,
100 300
150 350
200 400
250 450
,,,,,,,,
300 500
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400 600
500 700
600 800
,,,,,,,,
800 1000
1000 1200
1200 1400
1400 1600
1600 1800
1800 2000
2000 2200
A 300 350 400 450 500 600 700 800 1000 1200
,,,,
a > 1000
a
b 1200 1400 1600 1800 2000 B
100
,,,,
150
200
250
300 700
,,,,
400 800
500 900
600 1000
800 1200
,,,,
1000 1400
1200 1600
1400 1800
1600 2000
1800 2200
2000 2400
A 1400 1600 1800 2000 2200
All dimensions are in millimetres.
Figure A.15 Installation space dimensions A and B for flange jointed air ducts
with a firm obstacle on one side
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,,,,,,,,
a < 1000
a
b 100 150 200 250 300 400 500 600 800 1000 B
,,,,,,,,
,,,,,,,
100 300
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150 350
500
200 400
v
250 450
300 500
,,,,,,,
b
400 600
500 700
A 300 350 400 450 500 600 700 1000 1200 1400
500 800
,,,,,,,
800 1000
1000 1200
500
1200 1400
v
1400 1600
b
1600 1800
1800 2000
2000 2200
A 550 600 650 700 800 900 1000 1200 1400
,,,,
a > 1000
a
b 1200 1400 1600 1800 2000 B
100
,,,,
150
200
250
1000
300 700
,,,,
v 400 800
b
500 900
600 1000
800 1200
1000 1400
,,,,
A 1400 1600 1800 2000 2200
1200 1600
1000
1400 1800
v 1600 2000
1800 2200
b
2000 2400
A 1600 1800 2000 2200 2400
All dimensions are in millimetres.
Figure A.16 Installation space dimensions A and B for flange jointed air ducts with a
firm obstacle on two sides
28 BSI 1997
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,,,,,,,,
a < 1000
a
b 100 150 200 250 300 400 500 600 800 1000 B
,,,,,,,,
,,,,,,,
100 300
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150 350
500
200 400
v
250 450
300 500
,,,,,,,
b
400 600
500 700
A 500 550 600 650 700 800 900 1200 1400 1600
600 800
,,,,,,,
800 1000
1000 1200
500
1200 1400
v
1400 1600
b
1600 1800
1800 2000
2000 2200
A 750 800 850 900 1000 1100 1200 1400 1600
,,,,
a > 1000
a
b 1200 1400 1600 1800 2000 B
100
,,,,
150
200
250
1000
300 700
,,,,
v 400 800
b
500 900
600 1000
800 1200
1000 1400
,,,,
A 1600 1800 2000 2200 2400
1200 1600
1000
1400 1800
v 1600 2000
1800 2200
b
2000 2400
A 1800 2000 2200 2400 2600
All dimensions are in millimetres.
Figure A.17 Installation space dimensions A and B for flange jointed air ducts with a
firm obstacle on three sides
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,,,,,,,,
b + 600
> 1 000 f2 f2 a + 600
a < 1000
a
,,,,,,,,
b 100 150 200 250 300 400 500 600 800 1000 B
100 500
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150 550
500
200 600
,,,,,,,,
,,,,,,,
v
250 650
300 700
b
400 800
500 900
A 500 550 600 650 700 800 900 1200 1400 1600
,,,,,,,
600 1000
800 1200
1000 1400
500
1200 1600
,,,,,,,
v
1400 1800
b
1600 2000
1800 2200
2000 2400
A 750 800 850 900 1000 1100 1200 1400 1600
a > 1000
a
b 1200 1400 1600 1800 2000 B
,,,,
100
150
200
250
1000
,,,,
300 900
v 400 1000
b
500 1100
600 1200
800 1400
,,,,
1000 1600
A 1600 1800 2000 2200 2400
1200 1800
1000
1400 2000
v 1600 2200
1800 2400
b
2000 2600
A 1800 2000 2200 2400 2600
All dimensions are in millimetres.
Figure A.18 Installation space dimensions A and B for flange jointed air ducts with a
firm obstacle on four sides
30 BSI 1997
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Table A.6 Values of ea1, ea2, eb1 and eb2 (see figure A.21)
Dimensions in millimetres
ea1 ea, but with a min. of (t + f1) for a # 1000
ea, but with a min. of (t + f2) for a > 1000
eb1 eb, but with a min. of (t + f1) for a # 500 and b # 500 or a > 1000 and b # 1000
eb, but with a min. of (t + f2) for a # 500 and b > 500 or 500 < a # 1000 or a > 1000 and b > 1000
ea2 min. 500
eb2 min. 500
NOTE 1. For the values of ea and eb, see table A.5. f1 = 100 mm and f2 = 300 mm (see figure A.14).
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32
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a) Firm obstacle on one side b) Firm obstacle on two sides c) Firm obstacle on three sides d) Firm obstacle on four sides
Figure A.20 Installation space dimensions A and B for slip jointed air ducts with a firm obstacle on one or more sides
BS 8313 : 1997
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Table A.7 Values of ea1, ea2, eb1 and eb2 by firm obstacles
Dimensions in millimetres
Firm obstacle on one side Firm obstacle on two Firm obstacle on three Firm obstacle on four
sides sides sides
ea1 ea, but min. (t +f1) for ea, but min. (t +f1) for a # 500 or min. (t + f2) for a > 500
a # 1000 or min. (t + f2) for
a > 1000
ea2 t, but min. 100 t, but min. 100 min. 500
eb1 t, but min. 100 eb, but min. (t +f1) for b # 500 or min. (t +f2) or b > 500
eb2 t, but min. 100 t, but min. 100 min. 500 min. 500
NOTE 1. For the values of ea and eb, see table A.5. f1 = 100 mm and f2 = 300 mm (see figure A.14).
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NOTE. Working space dimensions ea1, ea2, eb1 and eb2 for air ducts jointed and insulated in position, by one or
more firm obstacles are given in table A.7.
Figure A.22 Minimum access allowance e for air ducts insulated in position
34 BSI 1997
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36 BSI 1997
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38 BSI 1997
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thin walled air ducts (wall thickness not B.4 Installation spaces for air ducts not
exceeding 15 mm) for ventilation, heating and air insulated or insulated before installation
conditioning of buildings. Installation spaces for air ducts not insulated or
insulated before installation are shown in figure B.1.
B.2 Field of application
The method is applicable to rectangular and circular B.5 Installation spaces for air ducts insulated
air ducts exceeding 100 mm on the smallest side after installation
or 100 mm diameter. It relates only to simple runs of B.5.1 Insulating methods
ducts and does not make allowance for fittings such as
Typical methods used for insulation after installation
dampers, bellows, silencers, filters or test points.
are as follows.
The installation spaces of adjacent services are allowed
a) Method 1. Insulating with rigid slabs, for example,
to overlap provided that the necessary clear space is
resin bonded mineral wool, fastened by thin steel
maintained around each service.
bands or the like. Without protective covering. (One
Where the allowances given by this method for operation.)
installation and removal of the air ducts are applied, it
b) Method 2. Insulating with soft, flexible materials
is permissible for part of the installation space to be
such as mats of mineral wool, with or without
used for other services or building components after
netting reinforcement and metallic facing, wrapped
the air ducts are installed and tested, provided that
around the air duct and sewed or clipped in
these can be removed if the air duct is to be removed.
position. Without protective covering. (One
The method is not applicable to the design of operation.)
installation spaces for services other than air ducts.
c) Method 3. Insulating as methods 1 or 2, but with
B.3 Interpretation, exceptions and limitations protective covering, for example sheet-metal. (Two
operations, first insulating, and then covering.)
B.3.1 The figures referred to in A.6 and A.7 show the
installation spaces recommended for access to the face d) Method 4. Insulating with rigid or flexible
of the air duct shown at the top of the figure. The size materials fixed to the duct by adhesive, with or
of the duct is the finished width of this face including without protective covering. (One or two
any external insulation but not flanges, cleats or other operations.)
joint components. The hatched area around each figure B.5.2 Installation spaces
denotes the area permitted for firm obstacles which
Installation spaces for ducts insulated after installation
may be part of the building or other services. A
are shown in figure B.2, and table B.1.
demountable casing may be installed in the installation
space. For insulating methods 1, 3 and 4, extra space may
need to be provided if rigid sheets of insulation or
covering more than 400 mm wide are to be used.
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b) Bolted flange joints, size of duct plus insulation > 500 but # 1000
d) Slip joints
All dimensions are in millimetres.
40 BSI 1997
BS 8313 : 1997
Figure B.2 Installation spaces for air ducts insulated after installation
Table B.1
Dimensions of X
Insulation method Dimension X
(see B.5.1) mm
1 125
2 125
3 200
4 200
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blank
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Normative references
BSI publications
BRITISH STANDARDS INSTITUTION, London
BS 476 : Fire tests on building materials and structures
BS 476 : Part 4 : 1970 Non-combustibility test for materials
BS 476 : Part 24 : 1987 Method for determination of fire resistance of ventilation ducts
BS 1710 : 1984 Specification for identification of pipelines and services
BS 2830 : 1994 Specification of suspended access equipment (suspended chairs,
traditional steeplejack's seats, work cages, cradles and platforms) for use
in the building, engineering construction, steeplejack and cleaning
industries
BS 4211 : 1994 Specification for ladders for permanent access to chimneys, other high
Licensed copy:Southbank University, 26/03/2008, Uncontrolled Copy, © BSI
BSI 1997 47
BS 8313 : 1997
Other references
[11] Liquefied Petroleum Gas Association Code of Practice No. 22. Coupar Angus: LPGA2), 1996
[12] Institution Of Gas Engineers. IGE/UP/2 Gas installation pipework, boosters and compressors on industrial
and commercial premises. London: IGE, 19943)
[13] Institution Of Gas Engineers. IGE/TD/4 Edition 3 Gas services. London: IGE, 1994
[23] Health & Safety Executive Guidance Note GS 5 Entry into confined spaces. Sudbury: HSE Books, 1995
[24]Institution Of Gas Engineers. IGE/SR/5 Entry into and work associated with confined spaces. London:
IGE, 1992
Informative references
BSI publications
Licensed copy:Southbank University, 26/03/2008, Uncontrolled Copy, © BSI
2) Available from William Culross and Sons Ltd., Coupar Angus, Perthshire PH13 9DF.
3) IGE publications are available from the Institution of Gas Engineers, 21 Portland Place, London W1N 3AF.
48 BSI 1997
BS 8313 : 1997
Other references
[1] GREAT BRITAIN. Approved Document published in connection with B2/B3/B4 of the Building
Regulations 1991. London: HMSO
[2] GREAT BRITAIN. Health and Safety at Work etc. Act 1974. London: HMSO
[3] GREAT BRITAIN. Asbestos (Licensing) Regulations 1983. London: HMSO
[4] GREAT BRITAIN. Asbestos (Prohibition) Regulations 1992. London: HMSO
[5] GREAT BRITAIN. Control of Asbestos at Work Regulations 1987. London: HMSO
[6] Health & Safety Executive Guidance Note EH 10 Asbestos Ð exposure limits and measurement of airborne
dust concentrations. Sudbury: HSE Books, 19904)
[7] Health & Safety Executive Guidance Note L 27 Control of asbestos at work Ð Approved code of practice.
Sudbury: HSE Books, 1993
[8] Health & Safety Executive Guidance Note L 28 Work with asbestos insulation, asbestos coating and
asbestos insulating board Ð Approved code of practice. Sudbury: HSE Books, 1993
[9] GREAT BRITAIN. Gas Safety Regulations 1972. London: HMSO
Licensed copy:Southbank University, 26/03/2008, Uncontrolled Copy, © BSI
[10] GREAT BRITAIN. Gas Safety (Installation and Use) Regulations 1994. London: HMSO
[14] Health & Safety Executive Guidance Note EH 22 Ventilation of the workplace. Sudbury: HSE Books, 1988
[15] Health & Safety Executive Guidance Note EH 40/94 Occupational exposure limits. Sudbury: HSE
Books, 1996
[16] Department of Health Technical Report HTR 2022 Medical gas pipeline systems Vol. 1-5. Leeds: NHSS
Estates5), 1994
[17] Department of Health Technical Report HTR 2023 Access and accommodation for engineering services
Vol. 1 & 2. Leeds: NHSS Estates5), 1995
[18] Health & Safety Executive Guidance Note EH 54 Assessment of exposure to fume from welding and allied
processes. Sudbury: HSE Books, 1990
[19] Health & Safety Executive Guidance Note EH 55 The control of exposure to fume from welding, brazing
and similar processes. Sudbury: HSE Books, 1990
[20] BASEEFA list. 8th edition Certified and approved explosion protected electrical equipment. Sudbury: HSE
Books, 1993
[21] Health & Safety Executive Guidance Note GS 16 Gaseous fire extinguishing systems Ð Precautions for
toxic and asphyxiating hazards. Sudbury: HSE Books, 1984
[22] Heating And Ventilating Contractors' Association. DW142 Specification for sheet metal ductwork Ð Low,
medium and high pressure/velocity air systems. London: Heating and Ventilating Contractors'
Association, 1982
[25] Health & Safety Executive Guidance Note EH 9 Spraying of highly flammable liquids. Sudbury: HSE
Books, 1977
[26] Eurovent Document 2/3 Sheet metal air ducts Ð Standard for dimensions. Bourne End: Heating,
Ventilating and Air Conditioning Manufacturers' Association6), 1976
4) HSE Guidance Notes are available from HSE Books, PO Box 1999, Sudbury, Suffolk CO10 6FS.
5) Available from NHSS Estates, Room 2E4, 1 Trevelyan Square, Boan Lane, Leeds LS1 6AE.
6) Available from the Heating, Ventilating and Air Conditioning Manufacturers' Association, 6 Furlong Road, Bourne End,
Buckinghamshire. SL8 5DG.
BSI 1997
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