NFPA 496 2021

$80.71

NFPA 496: Standard for Purged and Pressurized Enclosures for Electrical Equipment

Published By	Publication Date	Number of Pages
NFPA	2021	31

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Category: NFPA

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Description

Help mitigate risks by complying with the latest requirements for installing enclosures in Class I and Class II hazardous (classified) locations with NFPA 496. Electrical equipment fires, explosions, and other dangers relating to the ignition of a flammable atmosphere pose a significant threat to life and property. Help identify and minimize potentially deadly hazards and better safeguard facilities by referencing and complying with NFPA 496, Standard for Purged and Pressurized Enclosures for Electrical Equipment. This critical standard offers protection techniques applicable to Class I and Class II locations. You get comprehensive criteria for designing and operating purged and pressurized electrical equipment enclosures to minimize hazards in the presence of flammable materials. This standard applies to purging and pressurizing for the following: Electrical equipment located in areas classified as hazardous by Article 500 or Article 505 of NFPA 70®, National Electrical Code® (NEC®), 2020 edition. Electrical equipment containing sources of flammable vapors or gases that are located in either classified or unclassified areas Control rooms or buildings located in areas classified as hazardous by Article 500 or Article 505 of NFPA 70 Analyzer rooms containing sources of flammable vapors or gases that are located in areas classified as hazardous by Article 500 or Article 505 of NFPA 70 The revised NFPA 496 is updated for consistency with the most current knowledge and NEC, 2020 edition, requirements. It is vital electrical designers, installers, and AHJs have the most accurate and complete information for helping to ensure safety at Class I and Class II hazardous locations. This edition of the standard is updated to include significant changes in the Annex sections including: Updates to Annex 4.3.1 to clarify components that complete the enclosure are subject to the same considerations as the enclosure itself Details on methods to prevent the enclosure from excessive protective gas pressure added in A.4.3.1.1 Methods provided to prevent the discharge of ignition-capable particles to a Division 1 location in A.4.3.1.2 Included Annexes for 4.3.1 and its subsections to correlate with ANSI/ISA-12.04.04-2012, Pressurized Enclosures Added requirements to 4.4.5 for alarms on pressurizing system bypasses and safety measures to prevent their accidental opening, Introduction of French translations of required markings throughout the document New guidance, including a possible test, to confirm that enclosures do not contain trapped flammable gases in A.5.2.3 Revisions to A.5.2.6 to indicate that internal components in or through enclosure walls might not be adequately protected by purge/pressurization Addition of A.5.2.6.1 relating to internal components with a small internal volume that might not require protection Help ensure you are up to speed on the methods for purging and pressurizing electrical equipment enclosures to prevent the ignition of a flammable atmosphere.

PDF Catalog

PDF Pages	PDF Title
2	Important Notices and Disclaimers
3	Additional Important Notices and Disclaimers
8	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.
9	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.
10	3.4 NEC Extracted Definitions.
11	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.
12	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.
13	4.11 Type X Pressurizing. 4.12 Markings. Chapter 5 Pressurized Enclosures for Class I, or Zone 1, or Zone 2 5.1 Applicability. 5.2 General Requirements.
14	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 Class II 6.1 Applicability. 6.2 General Requirements. 6.3 Markings.
15	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.
16	Chapter 8 Pressurized Enclosures Having an Internal Source of Flammable Gas or Vapor 8.1 Applicability. 8.2 General Requirements. 8.3 Specific Requirements.
17	Chapter 9 Pressurized Analyzer Rooms Containing a Source of Flammable Gas, Vapor, or Liquid 9.1 Applicability. 9.2 General.
18	9.3 Specific Requirements. Annex A Explanatory Material
24	Annex B Informational References