This information is provided free of charge by the Department of Industrial Relations from its web site at These regulations are for the convenience of the user and no representation or warranty is made that the information is current or accurate. See full disclaimer at

Subchapter 7. General Industry Safety Orders
Group 20. Flammable Liquids, Gases and Vapors
Article 142. Industrial Plants

Return to index
New query

§5546. General.

This Section shall be applicable in those portions of industrial plants where flammable or combustible liquids are handled or used in unit physical operations such as mixing, drying, evaporating, filtering, distillation, and similar operations which do not involve chemical change. Examples are plants compounding cosmetics, pharmaceuticals, solvents, cleaning fluids, insecticides and similar types of activities.
(a) Emergency drainage systems shall be provided to direct flammable or combustible liquid leakage and fire protection water to a safe location. This may require curbs, scuppers, or special holding basins or tanks.
(1) Emergency drainage systems, if connected to public sewers or discharged into public waterways, shall be equipped with traps or separators.
(b) Areas as defined in Section 5546 using Category 1 or 2 flammable liquids, or Category 3 flammable liquids with a flashpoint below 100oF (37.8oC), shall be ventilated at a rate of not less than one cubic foot per minute per square foot of solid floor area. This shall be accomplished by natural or mechanical ventilation with discharge or exhaust to a safe location outside of the building. Provision shall be made for introduction of make-up air in such a manner as not to short circuit the ventilation. Ventilation shall be arranged to include all floor areas or pits where flammable vapors may collect. Local or spot general ventilation may be needed for the control of special fire or health hazards. Such ventilation, if provided, may be utilized for up to 75 percent of the required ventilation.
(c) Equipment used in a building and the ventilation of the building shall be designed so as to limit flammable vapor-air mixtures under normal operating conditions to the interior of equipment, and to not more than five feet from equipment which exposes Category 1 or 2 flammable liquids, or Category 3 flammable liquids with a flashpoint below 100oF (37.8oC), to the air. Examples of such equipment are dispensing stations, open centrifuges, plate and frame filters, open vacuum filters, and surfaces of open equipment.
(d) The storage, transfer and handling of liquids shall comply with Section 5557. (Title 24, T8-5546)
Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.
1. Amendment filed 7-16-76; effective thirtieth day thereafter (Register 76, No. 29).
2. Repealer of subsection (b) and consecutive relettering of subsections (c)-(e) filed 9-18-80; effective thirtieth day thereafter (Register 80, No. 38).
3. Amendment of subsections (b)-(c) filed 5-5-2014; operative 5-6-2014 pursuant to Government Code section 11343.4(b)(3) (Register 2014, No. 19).

Go BackGo Back to Article 142 Table of Contents