Fire Code Definitions for Compressed Gases

Corrosive: A chemical that causes visible destruction of, or irreversible alterations in, living tissue by chemical action at the point of contact. A chemical shall be considered corrosive if, when tested on the intact skin of albino rabbits by the method described in DOT n 49 CFR 173.137, such chemical destroys or changes irreversibly the structure of the tissue at the point of contact following an exposure period of 4 hours. This term does not refer to action on inanimate surfaces.

Flammable: Easily set on fire.

Flammable cryogenic fluid: A fluid having a boiling point lower than than -130°F (-89.9°C) at 14.7 pounds per square inch atmosphere (psia) (an absolute pressure of 101.3 kPa) that is flammable in its vapor state. 

Flammable gas: a material which is a gas at 68°F (20°C) or less at 14.7 pounds per square inch atmosphere (psia) (101kPa) of pressure [a material that has a boiling point of 68°F (20°C) or less at 14.7 psia (101 kPa) which:

  1. Is ignitable at 14.7 psia (101 kPa) when in a mixture of 13 percent or less by volume with air; or
  2. Has flammable range at 14.7 psia (101 kPa) with air of at least 12 percent, regardless of lower limit.

The limits specified shall be determined at 14.7 psi (101 kPa) of pressure and temperature at 68°F (20°C) in accordance with ASTM E 681.

Flammable liquefied gas: a liquefied compressed gas which, under a charged pressure is partially liquid at a temperature of 68°F (20°C) and which is flammable.

Highly toxic: A material which produces a lethal dose or lethal concentration which falls within any of the following categories:

  1. A chemical that has a median lethal concentration (LD­­50) in air of 200 parts per million by volume or less of gas or vapor, or 2 mg per liter or less of mist fume or dust, when administered by continuous inhalation for one hour (or less if death occurs within 1 hour) to albino rats weighing between 200 - 300 grams each.

Mixtures of these materials with inert gases might not warrant classification as highly toxic. While this system is basically simple in application, any hazard evaluation that is required for the precise categorization of this type of material shall be performed by experienced, technically competent persons.

Oxidizing cryogenic fluid: A fluid having a boiling point lower than than -130°F (-89.9°C) at 14.7 pounds per square inch atmosphere (psia) (an absolute pressure of 101.3 kPa) with oxidizing properties. 

Oxidizing gas: a gas that can support and accelerate combustion of other materials more than air does.

Pyrophoric: a chemical with an auto-ignition temperature in air, at or below a temperature of 130°F (54°C).

Toxic: A chemical falling within any of the following categories:

  1. A chemical that has a median lethal dose (LD50) in air of more than 200 parts per million by volume of gas or vapor or more than 2 mg per L but not more than 20 mg per liter of mist, fume or dust, when administered by continuous inhalation for 1 hour (or less if death occurs within 1 hour) to albino rats weighing between 200-300 grams each.

Unstable (reactive) material: a material other than an explosive, which in the pure state or as commercially produced, will vigorously polymerize, decompose, condense or become self-reactive and undergo other violent chemical changes, including explosion, when exposed to heat, friction or shock, or in the absence of an inhibitor, or in the presence of contaminants, or in contact with incompatible materials. Unstable (reactive) materials are subdivided as follows:

Class 4: Materials that in themselves are readily capable of detonation or explosive decomposition or explosive reaction at normal temperatures and pressures. This class includes materials that are sensitive to mechanical or localized thermal sock at normal temperatures and pressures.
Class 3: Materials that in themselves are capable of detonation or of explosive decomposition or explosive reaction but which require a strong initiating source or which must be heated under confinement before initiation. This class includes materials that are sensitive to thermal or mechanical shock at elevated temperatures and pressures.
Class 2: Materials that in themselves are normally unstable and readily undergo violent chemical change but do not detonate. This class includes materials that can undergo chemical change with rapid release of energy at normal temperatures and pressures, and that can undergo violent chemical changes at elevated temperatures and pressures.
Class 1: Materials that in themselves are normally stable, but which can become unstable at elevated temperatures and pressure.

Applicable Categories

  • Physical hazards: Flammable and gases, oxidizing gases, pyrophoric gases, unstable (reactive) gases, cryogenic fluids
  • Health hazards: Highly toxic and toxic materials, corrosive materials

5003.5 Hazard identification signs: Unless otherwise exempted by the fire code official, visible hazard identification signs as specified in NFPA 704 for specific material contained shall be placed on stationary containers and above ground tanks and at entrances to locations where hazardous materials are stored, dispensed, used or handled in quantities requiring a permit and at specific entrances and locations designated by the fire code official.

5003.5.1 Markings: Individual containers, cartons or packages shall be conspicuously marked or labeled in an approved manner. Rooms or cabinets containing compresses gases shall be conspicuously labeled: COMPRESSED GAS

 

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