Applying the API alternate method for area classification

The 1997 editions of API RP 500 and RP 505 pertaining to the classification of petroleum facilities included a new informative Annex - an alternate method for area classification. The intent of this paper is to go beyond the development of the alternate method and provide some insight and ideas on the application of the alternate method. The paper briefly covers the history behind the development of the alternate method. It then reviews the application of the method to specific sources of release and compare the results with other methods of evaluation such as the conventional methods described in RP 500/505 and the methods described in NFPA 497. Finally, the paper describes real life scenarios in which the alternate method has or could be used to evaluate difficult applications.