UL 2431 PDF

1.1 This standard is intended to provide a means to measure the ability of fire resistive materials to retain their fire resistive properties after being subjected to various conditioning environments. The fire resistive performance is determined by measuring temperatures of steel tubes, wide flange sections and plates protected by the materials.
1.2 Various types of conditioning environments are described. The conditioning environments include air erosion, a combination of wet, freeze and dry cycling, humidity, impact resistance, industrial atmosphere, salt spray, temperature stability, ultraviolet light, and vibration.
1.3 Two fire exposures are defined, a normal temperature rise fire and a rapid temperature rise fire. The normal temperature rise fire is intended to represent a fully developed interior building fire. The rapid temperature rise fire is intended to represent a hydrocarbon pool fire.
1.4 The conditioning environments and fire exposure tests are not intended to be representative of all exposure and fire conditions. With respect to fire exposure, conditions vary with changes in the amount, nature, and distribution of fire loading: ventilation; compartment size and configuration; and heat conducting and dissipating characteristics of the compartment in which the fire resistive material is installed.