1.1 This document specifies the constructional requirements for fans constructed to Group II G (of explosion groups IIA, IIB and hydrogen) categories 1, 2 and 3, and Group II D categories 2 and 3, intended for use in explosive atmospheres. NOTE 1 Operation conditions for the different categories of fans used in this document are defined in Clause 4. 1.3 This document specifies requirements for design, construction, testing and marking of complete fan units intended for use in potentially explosive atmospheres in air containing gas, vapour, mist and/or dusts. Such atmospheres can exist inside (the conveyed atmosphere (flammable or not)), outside, or inside and outside of the fan. This document covers mechanical equipment, in particular fans. The “type of protection” as specified in EN ISO 80079 37:2016 is constructional safety. 1.4 This document is applicable to fans working in ambient atmospheres and with normal atmospheric conditions at the inlet, having — absolute pressures ranging from 0,8 bar to 1,1 bar, — and temperatures ranging from −20 °C to +60 °C, — and maximum volume fraction of 21 % oxygen content, — and an aerodynamic energy increase of less than 25 kJ/kg. NOTE 1 25 kJ/kg is equivalent to 30 kPa at inlet density of 1,2 kg/m3. This document can also be helpful for the design, construction, testing and marking of fans intended for use in atmospheres outside the validity range stated above or in cases where other material pairings need to be used. In this case, the ignition risk assessment, ignition protection provided, additional testing (if necessary), manufacturer's marking, technical documentation and instructions to the user, clearly demonstrate and indicate the equipment's suitability for the conditions the fan can encounter. NOTE 2 Temperatures below −20 °C can be considered. Material suitability can require specific evaluation for these temperatures. With lower temperature the explosion pressure increases, which leads to increased test pressures (see A.3) and can require specific testing. Although the standard atmospheric conditions in EN ISO 80079 36:2016 give a temperature range for the atmosphere of −20 °C to +60 °C the normal ambient temperature range for the equipment is −20 °C to +40 °C unless otherwise specified and marked. 1.5 This document does not apply to: — group I fans (fans for mining); — explosion group IIC (other than hydrogen); — category 1D fans; — cooling fans or impellers on rotating electrical machines; — cooling fans or impellers on internal combustion engines, vehicles or electric motors. NOTE 3 Measures for category 1D fans are given in EN 1127 1:2019. NOTE 4 Measures for explosion group IIC (other than hydrogen) are given in EN 1127 1:2019. NOTE 5 Measures for explosion group I are given in EN ISO/IEC 80079 38:2016 and EN 1127 2:2014.