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BS 6656:1991

Superseded

Superseded

A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.

View Superseded by
superseded

A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.

Guide to prevention of inadvertent ignition of flammable atmospheres by radio-frequency radiation

Available format(s)

Hardcopy , PDF

Superseded date

30-10-2002

Language(s)

English

Published date

29-11-1991

Committees responsible
Foreword
Guide
1 Scope
2 Definitions
3 General considerations
4 Transmitters and transmitter output parameters
5 Structures and spark-making mechanisms
6 Ignition of flammable atmospheres
7 Practical measurements and tests
8 Methods of assessment
9 Plant safety measures
10 Special cases
Appendices
A Electromagnetic radiated fields and examples of
    aerial characteristics
B Subdivision of group II flammable gases and vapours
C Measurement of electromagnetic fields
D Methods of measurement on structures (on-site tests)
E Orford Ness transmitter site
F Examples of full assessment procedure
G Ground-wave propagation (vertical polarization):
    calculation of field strength
H Sources of information
Tables
1 Representative gases for gas groups
2 Radio-frequency power thresholds for structures
    excluding cranes
3 Radio-frequency energy thresholds for all structures
4 Radii of vulnerable zones
5 Radii of vulnerable zone for small structures at
    frequencies less than 30 MHz
6 Maximum radii of vulnerable zones
7 Radio-frequency power threshold for cranes
8 Maximum radii of vulnerable zones for ships'
    transmitters
9 Transmitters on platforms
10 Aerials for vertical polarization, for frequencies
    up to 30 MHz
11 Aerials for horizontal polarization, for frequencies
    up to 30 MHz
12 Aerials for frequencies above 30 MHz
13 Subdivision IIA
14 Subdivision IIB
15 Subdivision IIC
16 Extent of vulnerable zones (structure perimeter p >
    40 m)
17 Extent of vulnerable zones (structure perimeter p <
    or = 40 m)
18 Transmitter data (example 1)
19 Plant data (example 1)
20 Transmitter data (example 2)
21 Plant data (example 2)
22 Effective field strength for station transmitters
    (example 2)
23 Maximum extractable power from station transmissions
    (example 2)
24 Total extractable power at fr = 1.1 MHz (example 2)
25 Total extractable power at fr = 1.2 MHz (example 2)
26 Total extractable power at fr = 1.45 MHz (example 2)
27 Transmitter data (example 3)
28 Plant data (example 3)
29 Peak field strength for radar transmitters (example
    3)
30 Energy in structure from from pulse transmissions
    (example 3)
31 Advisory bodies
Figures
1 Typical loop-type structures
2 Assessment procedure flow chart
3 On-site test procedure flow chart
4 Safe threshold field strength versus frequency for
    single unmodulated transmissions
5 Field strength versus distance (land path)
6 Field strength versus distance (sea path)
7 Modulus match powers for Qk = 5
8 Example of reduction of structure efficiency
9 Test arrangements for measurement of extractable
    power
10 Test arrangement for indcendivity tests
11 Modulus match powers for structure resonated at 1.1
    MHz

Guidance in assessing the potential ignition hazard from radio and other transmitting aerials to plant where a potentially flammable atmosphere may be present.

Committee
EXL/31
DevelopmentNote
SUPERSEDES BS 6656: 1986
DocumentType
Standard
Pages
62
PublisherName
British Standards Institution
Status
Superseded
SupersededBy
Supersedes

BS 5908:1990 Code of practice for fire precautions in the chemical and allied industries
BS 7535:1992 Guide to the use of electrical apparatus complying with BS 5501 or BS 6941 in the presence of combustible dusts
BS 6701:1994 Code of practice for installation of apparatus intended for connection to certain telecommunication systems
BS 7777-1:1993 Flat-bottomed, vertical, cylindrical storage tanks for low temperature service Guide to the general provisions applying for design, construction, installation and operation

BS 5501-7:1977 Electrical apparatus for potentially explosive atmospheres Intrinsic safety \'i\'
BS 5501-1:1977 Electrical apparatus for potentially explosive atmospheres General requirements
BS 5345-2:1983 Code of practice for selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining applications or explosive processing and manufacture) Classification of hazardous areas
BS 5345-1:1989 Code of practice for selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining applications or explosive processing and manufacture) General recommendations

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