Cellular Phones in Class I, Division 2/Zone 2 Hazardous Locations

The risk associated with using a portable cellular phone in a class I, division 2 or zone 2 hazardous location is evaluated. Experimental trials were performed on a representative sample of commercial grade cellular phones using the guidelines provided in 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 1 and 2 Hazardous (Classified) Locations" (2002). The ignition risks are subsequently classified according to a framework ranking system for ignition sources developed by Rew and Spenser (1997). The results are used to construct a probability model that estimates the risk of a cell phone igniting a flammable atmosphere in a class I, division 2 or class I, zone 2 hazardous location. All cell phones evaluated did not meet 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. Additional testing and analysis of the high risk cell phone components indicated a very low probability of ignition even under ideal conditions. A Monte Carlo simulation of the probability model estimated the odds of a cell phone causing a fire or explosion in a class I, division 2 or class I zone 2 hazardous location as being 1.16E-06; or one in a million