Figure 22 – Examples of closing devices for unused apertures
12 Materials and mechanical strength of enclosures – Materials
inside the enclosures
12.1 Flameproof enclosures shall withstand the relevant tests prescribed in Clauses 14
through 16.
12.2 When several flameproof enclosures are assembled together, the requirements of this
standard apply to each of them separately, and in particular to the partitions separating them
and to all the bushings and operating rods which pass through the partitions.
12.3 When an enclosure contains several intercommunicating compartments, or when it is
subdivided because of the disposition of the internal parts, pressures and rates of rise of
pressure greater than normal may be produced.
Such phenomena shall be precluded as far as possible by the construction. If it is impossible to
avoid these phenomena, the resulting higher stresses shall be taken into account in the
construction of the enclosure.
12.4 When cast iron is used, the material shall be not less than the quality 150 (ISO 185).