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Definition(s)

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Class IIIA Liquids

Liquids having flash points at or above 60 °C (140 °F) and below 93 °C (200 °F. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global Standards

Definition(s)

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Class II Liquids

Liquids having flash points at or above 37.8 °C (100 °F) and below 60 °C (140 °F). API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global Standards

Definition(s)

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Combustible Liquid (Class II, IIIA, and IIIB Liquids)

Any liquid that has a closed-cup flash point at or above 37.8 °C (100 °F), as determined by the test procedures and apparatus outlined in NFPA 30. Combustible liquids are subdivided as follows: Class II liquids - Liquids having flash points at or above 37.8 °C (100 °F) and below 60 °C (140 °F). Class IIIA liquids - Liquids having flash points at or above 60 °C (140 °F) and below 93 °C (200 °F). Class IIIB liquids - Liquids having flash points at or above 93 °C (200 °F). API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global Standards

Definition(s)

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Class I Material Groups

For the purpose of testing, approval, and area classification, various air mixtures (not oxygen enriched) are subdivided into Groups A, B, C, or D for Class I, Division 1 and Class I, Division 2 locations. Group A—Atmospheres containing acetylene. Refer to Section 5.5, NEC Article 500.6(A)(1) and NFPA 497:3.3. Group B—A typical Class I Group B material is hydrogen. Refer to Section 5.5, NEC Article 500.6(A)(2), and NFPA 497:3.3 for a more complete definition. Group C—A typical Class I Group C material is ethylene. Refer to Section 5.5, NEC Article 500.6(A)(3), and NFPA 497:3.3 for a more complete definition. Group D—Atmospheres containing butane, gasoline, hexane, methane, natural gas, propane, and many other hydrocarbon gases and vapors encountered in oil and gas production, refining and pipeline operations. Refer to Section 5.5, NEC Article 500.6(A)(4), and NFPA 497:3.3 for a more complete definition. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global Standards

Definition(s)

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Class I, Division 2 Location

A Class I, Division 2 location is a location: 1) in which volatile flammable liquids or flammable gases are handled, processed, or used, but in which the hazardous liquids, vapors, or gases will normally be confined within closed containers or closed systems from which they can escape only if accidental rupture or breakdown of such containers or systems or abnormal operation of equipment occurs; or 2) in which hazardous concentrations of gases or vapors are normally prevented by positive mechanical ventilation but that might become hazardous through failure or abnormal operation of the ventilating equipment; or 3) that is adjacent to a Class I, Division 1 location, and to which hazardous concentration of gases or vapors might occasionally be communicated unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air, and effective safeguards against ventilation failure are provided. (See NEC Article 500 and API 500.) Source: API Recommended Practice 14FZ, Recommended Practice for Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Zone 0, Zone 1, and Zone 2 Locations, Second Edition, May 2013. Global Standards

Class I, Division 2 Location

A location in which flammable gases or vapors may be present, but normally are confined within closed systems; are prevented from accumulating by adequate ventilation; or the location is adjacent to a Division 1 location from which ignitable concentrations might occasionally be communicated. Reference 6.2.1.1.b and NEC Article 500.5(B)(2) for a more complete definition. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global Standards

Definition(s)

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Class I, Division 1 Location

A Class I, Division 1 location is a location: 1) in which ignitable concentrations of flammable gases or vapors exist continuously, intermittently, or periodically under normal operating conditions; or 2) in which ignitable concentration of such gases or vapors may exist frequently because of repair or maintenance operations or because of leakage; or 3) in which breakdown or faulty operation of equipment or processes might release ignitable concentrations of flammable gases or vapors, and might also cause simultaneous failure of electrical equipment (see NEC Article 500 and API 500). Source: API Recommended Practice 14FZ, Recommended Practice for Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Zone 0, Zone 1, and Zone 2 Locations, Second Edition, May 2013. Global Standards

Class I, Division 1 Location

A location in which ignitable concentrations of flammable gases or vapors are expected to exist under normal operating conditions or in which faulty operation of equipment or processes might simultaneously release flammable gases or vapors and also cause failure of electrical equipment. Reference 6.2.1.1.a and NEC Article 500.5(B)(1) for a more complete definition. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global Standards

Definition(s)

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Class I Location

A Class I location is one in which flammable gases or vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures. (See NEC Article 500 and NEC Article 505 and API 500 and API 505.). Source: API Recommended Practice 14FZ, Recommended Practice for Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Zone 0, Zone 1, and Zone 2 Locations, Second Edition, May 2013. Global Standards

Class I Location

A location in which flammable gases or vapors are, or may be, present in the air in quantities sufficient to produce explosive or ignitable mixtures. API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global Standards