Chapter 1 Administration 1.1 Scope. 1.2 Purpose. 1.3 Application. 1.4 Equivalency. 1.5 Units of Measurement. 1.6 Mandatory Rules, Permissive Rules, and Explanatory Material. Chapter 2 Referenced Publications 2.1 General. 2.2 NFPA Publications. 2.3 Other Publications. 2.4 References for Extracts in Mandatory Sections. Chapter 3 Definitions 3.1 General. 3.2 NFPA Official Definitions. 3.3 General Definitions. 3.4 NEC Extracted Definitions. Chapter 4 General Requirements for Pressurized Enclosures 4.1 Applicability. 4.2 Suitability of Identified Equipment. 4.3 Enclosure. 4.4 Pressurizing System. 4.5 Protective Gas System. 4.6 Determination of Temperature Marking. 4.7 Ventilated Equipment. 4.8 Power Switching Equipment. 4.9 Type Z Pressurizing. 4.10 Type Y Pressurizing. 4.11 Type X Pressurizing. 4.12 Markings. Chapter 5 Pressurized Enclosures for ClassI, or Zone 1, or Zone 2 5.1 Applicability. 5.2 General Requirements. 5.3 Markings. 5.4 Additional Requirements for Type Y or Type Z Pressurizing. 5.5 Additional Requirements for Type X Pressurizing. Chapter 6 Pressurized Enclosures for ClassII 6.1 Applicability. 6.2 General Requirements. 6.3 Markings. 6.4 Marking Information. 6.5 Additional Requirements for Type X Pressurizing. 6.6 Additional Requirements for Ventilated Equipment. Chapter 7 Pressurized Control Rooms 7.1 Applicability. 7.2 Protective Gas. 7.3 Considerations Relating to Positive Pressure Ventilation. 7.4 Requirements for Positive Pressure Air Systems. Chapter 8 Pressurized Enclosures Having an Internal Source of Flammable Gas or Vapor 8.1 Applicability. 8.2 General Requirements. 8.3 Specific Requirements. Chapter 9 Pressurized Analyzer Rooms Containing a Source of Flammable Gas, Vapor, or Liquid 9.1 Applicability. 9.2 General. 9.3 Specific Requirements. Annex A Explanatory Material Annex B Informational References