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 https://www.osha.gov.

March 31, 1983

SUBJECT: Request for Interpretations of 29 CFR 1910.106

In reference to your February 9, 1983 memorandum and a telephone conversation on the subject matter between A.O. Conley of your staff and Peter Wasko of my staff, the answer to your eight numbered questions are as follows:

1,7&8. The term,large quantity", used in 1910.106(h)(4)(iii)(a) must be interpreted in the same way as it is used in 1910.106(e)(2)(ii)(c), in reference to the quantity, by liquid class and container or tank type, in 1910.106(e)(2)(ii)(b)(1), (2), and (3). The quantity located outside of an inside storage room or storage cabinet becomes large when it exceeds respectively any one of the following:

(1) 25 gallons of Class IA liquids in containers.

(2) 120 gallons of Class IB, IC, II, or III liquids in containers.

(3) 660 gallons of Class IB, IC, II, or III liquids in a single portable tank.

For example, as little as 26 gallons of Class IA liquid or liquids in containers would be considered a large quantity. As a corollary, a quantity of flammable liquid is small when it does not exceed respectively the quantities in Items (1), (2) and (3) above. For example, the sum of the gallons in Items (1), (2), and (3) above could be as much as 805 gallons, and still be considered a small quantity, as long as not one of the three maximum quantities in Items (1), (2), and (3); viz., 25, 120 and 660 gallons, is respectively exceed.

2. 1910.106(h)(4) is concerned with liquid handling hazards that may lead to fire and/or explosion of flammable and combustible liquids.

3. 1910.106(h)(4) intends to reduce the unintentional escape of flammable or conbustible liquids and vapors and to minimize the quantity of liquid or vapor in case of accidental release. The open bucket transfer of Class 1 flammables, allowing for vapor release and potential spills, violates the intent of 1910.106(h)(4), but is in specific violation of 1910.106(e)(2)(iv)(d).

4. 1910.106(e)(2)(iv)(d) applies.

5&6. The term "transfer" in 1910.106(h)(4)(iii)(a) is not intended to be limited to a single quick transfer. Since neither the amount per transfer not the time interval between transfers is specified, the determination of "large quantities" in applying 1910.106(h)(4)(iii)(a) rests with the good judgement of the safety and health officer in evaluating the hazards of the employer's operation. For example, the intermittent transfer during an eight-hour shift of more than 660 gallons of Class IB, IC, II or III liquids from two portable 660-gallon tanks, (allowing one tank to replace the other, when empty, to maintain compliance with 1910.106(e)(2)(ii)(b)(3), into single vessel with unacceptable 5-gallon open pails would appear to be a poor operation practice. It could be cited using 1910.106(e)(3)(vi) and 1910.106(h)(4)(iii)(a) for unit physical operation.