API Recommended Practice 500, 4th Edition

api500API 500: Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and API 510: Pressure Vessel InspectionAPI 500, 3rd Edition – Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2 API