Standards development organization:
Type of Standard:
- Proceeding to development - No duplication identified
Comment period start date:
Comment period end date:
This part of IEC 60079 specifies the general requirements for construction, testing and
marking of Ex Equipment and Ex Components intended for use in explosive
The standard atmospheric conditions (relating to the explosion characteristics of the
atmosphere) under which it may be assumed that Ex Equipment can be operated are:
• temperature –20 °C to +60 °C;
• pressure 80 kPa (0,8 bar) to 110 kPa (1,1 bar); and
• air with normal oxygen content, typically 21 % v/v.
This part of IEC 60079 and other standards supplementing this standard specify
additional test requirements for Ex Equipment operating outside the standard
temperature range, but further additional consideration and additional testing may be
required for Ex Equipment operating outside the standard atmospheric pressure range
and standard oxygen content.
Such additional testing may be particularly relevant with respect to Types of Protection
that depend on quenching of a flame such as ‘flameproof enclosures “d”’ (IEC 60079-
1) or limitation of energy, ‘intrinsic safety “i”’ (IEC 60079-11).
NOTE 1 Although the standard atmospheric conditions above give a temperature range for the
atmosphere of -20 °C to +60 °C, the normal ambient temperature range for the Ex Equipment
is –20 °C to +40 °C, unless otherwise specified and marked. See 5.1.1. It is considered that –
20 °C to +40 °C is appropriate for many items of
Ex Equipment and that to manufacture all Ex Equipment to be suitable for a standard
atmosphere upper ambient temperature of +60 °C would place unnecessary design
NOTE 2 Requirements given in this standard result from an ignition hazard assessment made
on equipment. The ignition sources taken into account are those found associated with this
type of equipment, such as hot surfaces, electromagnetic radiation, mechanically generated
sparks, mechanical impacts resulting in thermite reactions, electrical arcing and static electric
discharge in normal industrial environments.
NOTE 3 Where an explosive gas atmosphere and a combustible dust atmosphere are, or can
be, present at the same time, the simultaneous presence of both often warrants additional
protective measures. Additional guidance on the use of Ex Equipment in hybrid mixtures
(mixture of a flammable gas or vapour with a combustible dust or combustible flyings) is given
in IEC 60079-14.
IEC 60079 does not specify requirements for safety, other than those directly related
to the explosion risk.
Ignition sources like adiabatic compression, shock waves, exothermic chemical
reaction, selfignition of dust, naked flames and hot gases/liquids, are not addressed
by this standard.
NOTE 4 Although outside the scope of this standard, such equipment would typically be
subjected to a hazard analysis that identifies and lists all of the potential sources of ignition by
the equipment and the measures to be applied to prevent them becoming effective. See