Hazardous areas classification

Instrument Purging for Reduction of Hazardous Area Classification... 

Hazardous Area Classification Codes Applied to the Same Pump... 

Cross-flow filtration systems are suitable for aqueous and solvent based solutions and suspensions, provided that electrical equipment is appropriately specified to meet relevant hazardous area classifications. Most systems are... 

Hazardous area classification zone, temperature classification, and gas group... 

The process of evaluating the likelihood of forming flammable atmospheres in plant areas is commonly referred to hazardous area classifications (HAG). HAG is usually conducted in accordance with regulations, codes, and standards such as the NEG/NFPA and NFPA NEG/NFPA 70 classifies... 

These engineers do not normally contribute any power consumption data, but their input to the work of the electrical engineer is to advise on subjects such as equipment layout, access to equipment, maintainability, maintenance lay-down space, emergency exit routing, operational philosophies of plant and systems, hazardous area classification. 

Some of the earliest work on the subject of hazardous area classification was documented by the API, IP and BS institutions, and the chemical manufacturing company ICI. Their particular documents are given in Table 10.1. 

Table 10.1. Early publications pertaining to hazardous area classification...

The concepts of hazardous area classification and the legislation that supports the subject are in a continuous state of revision and so the engineer should keep abreast of such developments. 

However, this method is not used for medium and large industrial drives, because of the practical difficulty in designing a high resistance rotor. If a slip-ring wound rotor design is used then an external high resistance can be added, but this method is seldom acceptable in the oil industry because of restrictions imposed by hazardous area classification. 

Pressure relief valves and rupture disk Hazardous area classification drawings... 

Areas outside the tank in which the conditions listed above do not exist are designated as non-hazardous. Table 7.6 provides an example of a typical hazardous area classification for storage tanks containing a highly flammable solvent (flash point less than 32°C). The procedure for identification of sources of release, determination of the type of hazardous zone and the process for assessment of the extent of the zone are detailed in British Standard 5345 Part 1 and Part 2 [17]. 

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