Interlocks and barriers around rotating barrels

November 18, 1981

Mr. William C. Crager
Safety Consultant
[Recipient address omitted]
Dear Mr. Crager,

Your October 16, 1981 letter to our New York Regional Office has been forwarded to us for response. You requested an interpretation of 29 CFR 1910.212(a)(4).

There are several acceptable methods by which employers may comply with the requirement of 29 CFR 1910.212(a)(4). An interlocked enclosure of each device is certainly one alternative. However, many employers prefer to isolate the area in which more than one device is installed, either because the process is not compatible with individual enclosures, or the cost of individual enclosures is determined to be prohibitive.

Therefore, where the devices are grouped together in a common area and they are enclosed by a barrier guard, partitions or wells, the access opening must be equipped with an interlocking device which prevents all barrel, drum, or container rotation when employee access occurs. Furthermore, under such circumstances, the operating controls must necessarily be outside of the enclosure and must require intentional manual restart after each interruption caused by activation of the access door interlock.

When the devices are located out of visual sight from the control panel, such as behind an opaque wall, the controls must be effectively locked-out whenever employees enter the enclosed area.

OSHA's concern is in regard to eliminating employee exposure to the hazards of revolving barrels, drums and containers. Any effective system by which this is accomplished would be acceptable.

If we may be of further assistance, please call or write.

Sincerely,

Patrick R. Tyson
Acting Director, Federal compliance
and State Programs