NFPA 497-2021
易燃液体、气体或蒸气分类以及化学工艺区电气装置危险(分类)场所分类的推荐做法(生效日期:04/04/2020)
Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas (Effective Date: 04/04/2020)