In light liquid service

In light liquid service means that a piece of equipment in regulated material service contains a liquid that meets the following conditions:
(1) The vapor pressure of one or more of the compounds is greater than 0.3 kilopascals at 20 °C.
(2) The total concentration of the pure compounds constituents having a vapor pressure greater than 0.3 kilopascals at 20 °C is equal to or greater than 20 percent by weight of the total process stream.
(3) The fluid is a liquid at operating conditions.

Source

40 CFR § 98.128

Scoping language

Except as provided in this section, all of the terms used in this subpart have the same meaning given in the Clean Air Act and subpart A of this part. If a conflict exists between a definition provided in this subpart and a definition provided in subpart A, the definition in this subpart shall take precedence for the reporting requirements in this subpart.