1. Scope 1.1 This standard specifies the constructional features and test requirements
for flameproof enclosures of electrical apparatus intended to be used in
explosive gas atmospheres. In addition, flameproof enclosures shall comply
with the applicable requirements of IEC 79-0. This standard applies to enclosures and parts of enclosures constructed of
metallic and non-metallic materials. Some additional requirements may be
necessary for non-metallic materials and these are left to the discretion
of the national or other appropriate authority.
See Appendix A. 1.2 The ambient temperature range of -20 °C to +60 °C for the explosive gas
atmosphere characteristics and -20 °C to +40 °C for the operation of
electrical apparatus as given in IEC 79-0, also apply to this standard.
For ambient temperatures below -20 °C, stronger enclosures may be required
due to the higher explosion pressures generated at low temperatures and the
possibility of brittle failure of enclosure materials. For ambient
temperatures above 60 °C, it may be necessary to use smaller joint gaps
because the maximum safe gap tends to decrease with an increase in ambient
temperature. 1.3 This part of IEC 79 deals only with flameproof enclosures and not with
other means of protection against an explosion hazard. These are covered
by separate standards.