The BARTEC Academy
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Protection Principles
Protection principles are defined to prevent equipment and components becoming ignition sources.
The protection principles can be applied to electrical and non-electrical equipment and for gases and dusts. The principles allow for a design in various safety categories in accordance with the Directive 2014/34/EU or the Equipment Protection Level (EPL) according to EN- IEC 60079-0 series:
| Equipment category 1 | very high level of protection and thus a very high degree of safety |
| Equipment category 2 | high level of protection and therefore a high degree of safety |
| Equipment category 3 | normal level of protection and therefore a conventional degree of safety |
| Equipment Level of Protection a | very high level of protection and thus a very high degree of safety |
| Equipment Level of Protection b | high level of protection and therefore a high degree of safety |
| Equipment Level of Protection c | normal level of protection and therefore a conventional degree of safety |
Ignition sources which are caused by sparks from friction or impact or from electro-static charging have to be prevented in explosion protected equipment by selecting appropriate materials and by constructive measures, and this must be verified and confirmed by appropriate tests. Four protection principles can prevent equipment from becoming an ignition source. The types of protection listed as examples in the overview are discussed in a different chapter.
An important precondition for all the protection principles is that parts which are in unhindered contact with the explosive atmosphere must not be able to reach non-permitted temperatures with respect to the ignition temperature of substances present in the site of installation. This means that the ignition temperature is relevant for all protection principles.
Explosive mixtures can enter the equipment in which an ignition source may be located and be ignited. The transmission of internal ignition to the surrounding atmosphere shall be excluded.
Examples of types of protection:
- Flameproof enclosures (Ex d) - electrical and non-electrical equipment
- Powder (quartz) filling (Ex q) - electrical equipment
The operating equipment has an enclosure which prevents the penetration of the explosive mixture and/or contact with the internal function-related potential sources of ignition.
Examples of types of protection:
- Pressurized enclosures (Ex p) - electrical and non-electrical equipment
- Protection by enclosures (Ex t) - electrical equipment
- Liquid immersion (Ex o) - electrical equipment
- Liquid immersion (Ex h (previous k)) - non-electrical equipment
- Encapsulation (Ex m) - electrical equipment
Explosive mixtures can penetrate the enclosure of the operating equipment but is not allowed to be ignited. Any spark is prohibited and temperatures capable of causing ignitions shall be prevented.
Examples of types of protection:
- Increased Safe equipment (Ex e) - electrical equipment
- Non-sparking equipment (Ex nA) - electrical equipment
- Protection by constructional safety (Ex h (previous c)) - non-electrical equipment
Explosive mixtures can penetrate the enclosure of the operating equipment but can’t be ignited. The occurrence of spark energy and increased temperatures shall be limited.
Examples of types of protection:
- Intrinsically safe (Ex i) - electrical equipment
- Protection by control of ignition source (Ex h (previous b)) - non-electrical equipment