Mobile Phones in Category 3 Explosive Gas Atmospheres

The risk associated with using a mobile phone in a Category 3 (Zone 2) Explosive Gas Atmosphere is evaluated. Experimental trials were performed on a representative sample of commercial grade mobile phones using the guidelines provided in The Instrumentation, Systems, and Automation Society's ISA-RP12.12.03-2002 "Recommended Practice for Portable Electronic Products Suitable for Use in Class I and II, Division 2, Class I Zone 2 and Class III, Division I and 2 Hazardous (Classified) Locations" [1]. The ignition risks are subsequently classified according to a framework ranking system for ignition sources developed by Rew and Spenser (1997)[2]. The results are used to construct a probability model that estimates the risk of a mobile phone igniting a flammable atmosphere in a Category 3 explosive gas atmosphere. The IEC or ATEX has not issued a equivelant standard to ISA-RP12.12.03-2002 for portable electronic products. The development of a harmonized standard is currently under review.. While the ISA Standard references the terms Class I and II, Division 2, Class I Zone 2 and Class III, Division I and 2 Hazardous (Classified) Locations" these terms are essentially equivalent to the definitions used by the IEC and/or CENELEC for Category 3, Zone 2 and Zone 22 locations. Not all the mobile phones evaluated met the ISA-RP12.12.03-2002 requirements for a PEP 2 (Portable Electronic Product) device and therefore could not be considered "incapable of causing an ignition under normal operating conditions" as per the PEP definition.