Hazardous Area Classification Class I: Zone 0, Zone 1, Zone 2
The main purpose of hazardous area classification is the proper selection and installation of electrical equipment and instrument in hazardous zones. For this purpose, it is essential to identify the extent of the area made hazardous due to the presence of explosive atmosphere, to classify it and to select the degree of hazard according to the probability of occurrence and the grade of release.
In addition, this assessment should not be considered separately, but as part of an overall safety strategy for a location where the problem occurs. Having identified the possible presence of an explosive atmosphere, it is then required to identify the equipment which really needs to be present, and ensure their protection in a way that makes the overall risk of an explosion sufficiently low.
The identification and classification needs to be undertaken using the guidance given in the UK Energy Institutes Model Code of Safe Practice following
- Area Classification Code for Installations Handling Flammable Fluids – IP15
- IEC 60079-10-1 Explosive Atmospheres – Explosive Gas Atmospheres
- IEC 60079-10-2 Explosive Atmospheres – Classification of Areas, Combustible Dust Atmospheres.
International codes, standards and articles made to asses the best engineering of petroleum plants include:
- API RP 505 : Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Zone 0, Zone 1, and Zone 2
- NFPA 70 : National Electrical Code
Area classification is not simply intended to identify hazardous areas on process plants where design has already been completed using only operational and economic factors as influence, but to be part of the design process and to significantly affect the design process in order to minimize the explosion risks. This means that hazardous areas should be eliminated as far as is possible, leaving only those which are absolutely necessary and introduce only an acceptable level of risk. For new or modified plant the process should be carried out as early as possible in the project life cycle, normally when the initial process, instrumentation and layout diagrams are available and should be constantly refined throughout the design process, influencing all stages of process design.
Hazardous Area Specialist | E&I Project Engineer | Certified Energy Auditor
4 年The question which degree of awareness is in personal? Are people well trained to deal with Hazardous Area? Are our regulations are up-to-date and well applied?
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4 年Good assessment Majdi. Where this is not possible to eliminate the likelihood of an explosive gas atmosphere occurring around the source of ignition, or to eliminate the source of ignition, protective measures, process equipment, systems and procedures should be selected and prepared so the likelihood of the coincidence of is so small as to be acceptable.