Type of protection according to IEC, EN, ISA, and UL | Basic principle | Main application |
General requirements IEC 60079-0 EN 60079-0 UL 60079-0 | This standard sets out the general requirements for explosion-protected electrical equipment. The equipment marking is also described in this standard. | |
Flameproof enclosure "d" IEC 60079-1 EN 60079-1 UL 60079-1 | Parts which can ignite an explosive atmosphere are surrounded by an enclosure which withstands the pressure of an explosive mixture exploding inside the enclosure and prevents the transmission of the explosion to the atmosphere surrounding the enclosure. | Switching equipment and switchgears, control and indicating equipment, control systems, motors, transformers, heating equipment, light fittings da = Use in Zone 0, 1, 2 db = Use in Zone 1, 2 dc = Use in Zone 2 |
Pressurised enclosure "p" IEC 60079-2 EN 60079-2 UL 60079-2 | The formation of an explosive atmosphere inside an enclosure is prevented by maintaining a positive internal pressure of inert gas in relation to the surrounding atmosphere and, where necessary, by supplying the inside of the enclosure with a constant flow of inert gas which acts to dilute any combustible mixtures. | Switching and control cabinets, analytical instruments, large motors pxb = Use in Zone 1, 2 or Zone 21, 22 pyb = Use in Zone 1, 2 or Zone 21, 22 pzc = Use in Zone 2 or Zone 22 |
Powder filling "q" IEC 60079-5 EN 60079-5 UL 60079-5 | Filling the enclosure of an item of electrical equipment with a fine granular packing material has the effect of making it impossible for an electric arc created in the enclosure under certain operating conditions to ignite an explosive atmosphere surrounding the enclosure. Ignition must not result either from flames or from raised temperatures on the surface of the enclosure. | Sensors, electronic ballasts, transmitters q = Use in Zone 1, 2 |
Oil immersion "o" IEC 60079-6 EN 60079-6 UL 60079-6 | Electrical equipment or parts of electrical equipment are immersed in a protective fluid (such as oil), such that an explosive atmosphere present over the surface or outside of the enclosure cannot be ignited. | Transformers, starting resistors o = Use in Zone 1, 2 |
Increased safety "e" IEC 60079-7 EN 60079-7 UL 60079-7 | Here, additional measures are taken to increase the level of safety, thus preventing the possibility of inadmissibly high temperatures and the occurrence of sparks or electric arcs within the enclosure or on exposed parts of electrical equipment, where such ignition sources would not occur in normal operation. | Terminal and connection boxes, control boxes for installing Ex-components (which have a different type of protection), squirrel-cage motors, light fittings eb = Use in Zone 1, 2 ec = Use in Zone 2 |
Intrinsic safety "i" IEC 60079-11 EN 60079-11 UL 60079-11 | Equipment that is used in a potentially explosive atmosphere only contains intrinsically safe electric circuits. An electric circuit is intrinsically safe if no sparks or thermal effects are produced under specified test conditions (which include normal operation and specific fault conditions) which might result in the ignition of a specified explosive atmosphere. | Measuring and control technology, fieldbus technology, sensors, actuators ia = Use in Zone 0, 1, 2 or Zone 20, 21, 22 ib = Use in Zone 1, 2 or Zone 21, 22 ic = Use in Zone 2 or Zone 22 [Ex ib] = associated electrical equipment – installation in the safe area |
Type of protection "n" IEC 60079-15 EN 60079-15 UL 60079-15 | Electrical equipment cannot ignite an explosive atmosphere surrounding it (during normal operation and under defined abnormal operating conditions). | All electrical equipment for Zone 2 nA = non-sparking equipment nC = sparking equipment and components nR = restricted breathing enclosures |
Encapsulation "m" IEC 60079-18 EN 60079-18 UL 60079-18 | Parts which may ignite an explosive atmosphere are embedded in sealing compound such that the explosive atmosphere cannot be ignited. | ma = Use in Zone 0, 1, 2 or Zone 20, 21, 22 mb = Use in Zone 1, 2 or Zone 21, 22 mc = Use in Zone 2 or Zone 22 |
IEC 60079-25 EN 60079-25 ISA 60079-25 | Intrinsic safety evaluation for defined systems (equipment and cables). | Intrinsically safe systems |
Optical radiation "op" IEC 60079-28 EN 60079-28 ISA 60079-28 | Suitable measures prevent ignition of an explosive atmosphere by optical radiation. | Fibre optics/use in potentially explosive gas atmospheres. There are three different methods: Ex op is = inherently safe optical radiation Ex op pr = protected optical radiation Ex op sh = optical radiation with interlock |
Protection by enclosure "t" IEC 60079-31 EN 60079-31 | Thanks to the tightness of the enclosure, dust cannot penetrate at all or the amount which can is limited to a safe level. For this reason, ignitable equipment can be installed in the enclosure. The enclosure's temperature must not ignite the surrounding atmosphere. | Switching equipment and switchgears, control, connection and terminal boxes, motors, transformers, light fittings ta = Use in Zone 20, 21, 22 tb = Use in Zone 21, 22 tc = Use in Zone 22 |