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.

July 28, 1980

Mr. John B. Howell
Safety Director
BEMIS Manufacturing Company
Sheboygan Falls, Wisconsin 53085

Dear Mr. Howell:

Assistant Secretary Eula Bingham has asked me to respond to your letter dated July 11, 1980, requesting a variance from Section 1910.178 Powered Industrial Trucks - Class III, Division 2 Location, of the Occupational Safety Standards.

You are requesting a variance to convert your gasoline powered industrial truck to a liquefied petroleum (LP) gas powered unit. You also plan to retrofit the industrial truck with additional safeguards on the exhaust, fuel, and electrical systems.

After a careful evaluation, we have determined that the conversion of your gasoline unit to a LPS unit with additional safeguards is acceptable if all components used on the unit are approved by a nationally recognized laboratory such as Underwriters Laboratories, Inc. or Factory Mutual Engineering Corporation. The installation/conversion shall also comply with the following:

1. All applicable OSHA standards shall be observed.

2. Units and fitting used for the conversion shall be installed in strict conformity with requirements specified in the National Fire Prevention Association Standard No. 58, Storage and Handling of Liquefied Petroleum Gases, and Underwriters Laboratories No. 558, Standard for Safety - Internal Combustion Engine - Powered Industrial Trucks.

3. The manufacturer should also be consulted. When an industrial truck is converted to a LPS gas operation, the manufacturer may be able to supply listed conversion units and assign a qualified representative to supervise the installation.

Copies of the above standards may be obtained from the:

National Fire Protection Association
470 Atlantic Avenue
Boston, Massachusetts 02210


Underwriters Laboratories, Inc.
207 East Ohio Street
Chicago, Illinois 60611

Affected employees and their authorized representative shall be notified of our decision concerning this matter in the same manner they were notified of your request for variance.

If you have any further questions, please feel free to contact my office at (202) 523-7144.


James J. Concannon Director
Office of Variance Determination