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124 Electrical installations in hazardous areas

they are not accurate, but merely that work needs to be done to increase
experience in their use by practicing engineers to further our understanding
of the parameters within which they can be used. This set of formulae also
will be more difficult to use in cases of liquid release, particularly where
that liquid is below its boiling point.
Finally, Table 4.1 is included (Fig. 4.5 from BS 5345 Part 2l) and gives
some of the information necessary to use the calculative methods used in
this chapter. This table also includes two columns titled respectively ’Group’
and ‘Temperature Class’. These will be described in more detail in Chapter
7 as they refer to apparatus performance. They are listed here to identify the
relationship of the explosive atmospheres occurring to the type of apparatus
which should be used.

References

1 BS 5345 Selection, Installation and Maintenance of Electrical
Apparatus for use in Potentially Explosive Atmo-
spheres (other than mining applications or explosives
processing or manufacture). Part 2 (1983). Classifica-
tion of hazardous areas.
2 RoSPA/ICI Engineering Codes and Regulations, Electrical Instal-
lations in Flammable Atmospheres (1973). Group C
(Electrical), Volume 1.5.
3 BS/EN 60079-10 Electrical Apparatus for Explosive Atmospheres /
Classification of hazardous areas (1996).
4 Chemical Engineers Hardbook (Editions 1-6). Latest
edition. Edition 6 (1984) R.H. Perry and 0. Green.
5 BSI 79/27013 BSI Committee GEL/114/5 Draft Document produced
in preparation of BS 5345.
6 Lipincott, S.B. and Lyman, M.L. (1946). Vapour Pres-
sure/Temperature Monographs. Industrial Engineering
and Chemistry (38) 3.
7 Chartered Institution of Building Services (1970).
Natural Infiltration into Bujldings (guide book).