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AST Definitions

Atmospheric tank: a storage tank which has been designed to operate at pressures from atmospheric through 0.5 psig.

Container: any can, barrel (a volume of 42 gallons), or drum (up to 60 gallons).

Closed container: a container sealed by means of a lid or other device that neither liquid nor vapor will escape from it at ordinary temperatures.

Flashpoint: the minimum temperature at which a liquid gives off vapor within a test vessel in sufficient concentration to form an ignitable mixture with air near the surface of the liquid.

Flammable liquid: any liquid having a flashpoint at or below 199.4 degrees F (93 degrees C). Flammable liquids are divided into four categories:

  1. Category 1: liquids having a flashpoint below 73.4 degrees F (23 degrees C), and having a boiling point at or below 95 degrees F (35 degrees C).
  2. Category 2: liquids having a flashpoint below 73.4 degrees F (23 degrees C), and having a boiling point above 95 degrees F (35 degrees C).
  3. Category 3: liquids having a flashpoint at or above 73.4 degrees F (23 degrees C) and at or below 140 degrees F (60 degrees C).
  4. Category 4: liquids having a flashpoint above 140 degrees F (23 degrees C) and at or below 199.4 degrees F (93 degrees C).

Portable tank: a closed container having a liquid capacity over 60 gallons and not intended for fixed installation.

Pressure vessel: a storage tank or vessel which has been designed to operate at pressures above 15 psig.

Safety can: an approved container, of not more than 5 gallons capacity, having a spring-loaded/closing lid and spout cover, and so designed that it will safely relieve internal pressure when subjected to fire exposure.