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Standard Interpretations - Table of Contents
• Standard Number: 1910.178

June 3, 1993

W. F. Dillon
Assistant Commissioner for Enforcement
Department of Labor and Industry
Commonwealth of Virginia
Powers Taylor Building
13 South Thirteenth Street
Richmond, Virginia 23219

Dear Mr. Dillon:

This is in response to the inquiry regarding use of a powered industrial truck to dump hexamine into a hopper of a bucket elevator, which could result in ignitable or explosive mixtures being generated. Response to the inquiry will be in a question and answer format. Questions and answers are as follows:

Q. 1. Is the employer mentioned in your letter in violation of OSHA Standard 29 CFR 1910.178(c)(2)(vi)(a)? They use a powered industrial truck, not approved for use in atmospheres that can contain combustible dusts, in an operation where a cloud of combustible dust can be created.

R. Yes. Based on the information provided in your letter they are in violation of the referenced OSHA standard. (The source standard for 1910.178(c)(2)(vi)(a) is NFPA No. 505-1969, Powered Industrial Trucks.) The OSHA standard reads as follows:

"Only approved power operated industrial trucks designated as EX shall be used in atmospheres in which combustible dust is or may be in suspension continuously, intermittently, or periodically under normal operating conditions, in quantities sufficient to produce explosive or ignitable mixtures, or where mechanical failure or abnormal operation of machinery or equipment might cause such mixtures to be produced".

If the bucket elevator failed or malfunctioned while the powered industrial truck is dumping hexamine, it is possible sufficient quantities of the dust could be thrown into the air to create an explosive or ignitable mixture.

Q. 2. What options does the employer have in abating the violation of 1910.178(c)(2)(vi)(a).

R. The employer may do one of three things. They are:

1. Obtain and use a powered industrial truck with an EX designation.

2. Develop another type of dumping system that does not involve use of a powered industrial truck for the actual dumping process. The truck will have to be out of the area during actual dumping of hexamine. A dumping system such as recommended by the inspector will be satisfactory.

3. Modify the equipment and/or process so combustible dust will not normally be in the air, or thrown into the air by the abnormal operation of equipment, in sufficient quantities to produce explosive or ignitable mixtures. The employer should supply documentation, not just opinions, that any modifications, including the use of a ventilation system, will actually eliminate the chance of creation of an explosive or ignitable mixture.

If the modification(s) eliminates the chance of an explosive or ignitable mixture being created an industrial truck designated as EX, EE or DY may be used.

If we can provide any further assistance relative to this matter, please contact John Mcfee of my staff at (215) 596-1201.


Regional Administrator

Standard Interpretations - Table of Contents

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