This European Standard specifies the basic method and requirements for design, construction, testing and marking of non-electrical equipment intended for use in potentially explosive atmospheres in air of gas, vapour, mist and dusts. Such atmospheres can also exist inside the equipment. In addition, the external atmosphere can be drawn inside the equipment by natural breathing produced as a result of fluctuations in the equipment’s internal operating pressure, and/or temperature. This European Standard is valid for atmospheres having pressures ranging from 0,8 bar to 1,1 bar and temperatures ranging from - 20 °C to + 60 °C., i.e. equipment built to this European Standard will be satisfactory to any service conditions within this range unless otherwise specified. NOTE 1 The requirements of this European Standard can also be helpful for the design, construction, testing and marking of equipment intended for use in atmospheres outside the validity range stated above. In this case however, the ignition hazard assessment, ignition protection provided, additional testing (if necessary), manufacturer’s technical documentation and instructions to the user, should clearly demonstrate and indicate the equipment’s suitability for the conditions it may encounter. It should also be recognized that changes in temperature and pressure can have a significant influence on ignitability.