Capacity of a flammable-liquid storage cabinet

October 26, 2011

James C. Williamson, CEP, CHMM

[Recipient address omitted]

Dear Mr. Williamson,

Thank you for your letter dated September 1, 2011, to the Occupational Safety and Health Administration (OSHA). You asked for clarification on an apparent ambiguity in OSHA's standard for Flammable and Combustible Liquids, 29 CFR 1910.106.

Specifically, you asked for clarification on the use of the words "or" and "nor" in the paragraph Design, Construction, and Capacity of Storage Cabinets-Maximum Capacity, 29 CFR 1910.106(d)(3)(i), which states, "Not more than 60 gallons of Class I or Class II liquids, nor more than 120 gallons of Class III liquids may be stored in a storage cabinet."

This language is an adaptation of similar language in section 4210 of the 1969 edition of the National Fire Protection Association's (NFPA) Standard 30, Flammable and Combustible Liquids (source standard for 29 CFR 1910.106), which states, "Not more than 60 gallons of flammable or 120 gallons of combustible liquids may be stored in a storage cabinet."

You correctly point out that the use of "or" and "nor" above is ambiguous and that users might interpret these requirements differently. You list multiple possible interpretations in your letter, including, but not limited to:

• storage cabinets used to store Class I or Class II liquids, but not both;

• storage cabinets used to store 60 gallons of flammable liquids or 120 gallons of combustible liquids, but no combination of flammable and combustible liquids; and

• storage cabinets used to store 60 gallons of Class I and Class II liquids and 120 gallons of combustible liquids, for a total volume of 180 gallons.

OSHA never intended to prohibit intermingling flammable and combustible liquids in a storage cabinet or to allow more than 120 gallons of any flammable and combustible liquids combination in a storage cabinet.

NFPA 30 - 1981 Section 4-3.1 states, "Not more than 120 gal (454.2L) of Class I, Class II, and Class IIIA liquids may be stored in a storage cabinet. Of this total, not more than 60 gal (227.1L) may be of Class I and Class II liquids..." OSHA finds this language represents the intent of 29 CFR 1910.106(d)(3)(i) clearly and unambiguously.

Thank you for your interest in occupational safety and health. OSHA requirements are set by statute, standards, and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov. If you have any further questions, please feel free to contact the Office of General Industry Enforcement at (202) 693-1850.

Sincerely,

Thomas Galassi, Director

Directorate of Enforcement Programs