For more information, go to: HSE Safety Alert

Washington, DC, July 26, 2006 - On December 11, 2005, there was a major fire and explosion at the Buncefield petroleum storage depot in Hemel Hempstead, England. The initial report of the investigation into the incident was published on July 13, 2006.

The report indicates that the explosion probably resulted from the ignition of a vapor cloud formed when a tank containing unleaded gasoline overflowed. One aspect of the investigation is the operation of the "ultimate high level switch" on the tank. It is part of the system designed to prevent the tank from overflowing.

The United Kingdom Health and Safety Executive (HSE) has issued a safety alert on the proper installation and testing of the type of level switch installed on the tank that overflowed. The safety alert includes a checklist to aid in identifying and testing the switches. Although these types of level switches are manufactured in the United Kingdom, the HSE believes that they may have been supplied to customers throughout Europe and North America.

The safety alert is primarily for the attention of those companies operating oil/fuel storage facilities. However, it may also be relevant to other sites storing hazardous substances in large tanks where level gauges are used.

The CSB has provided this notice at the request of U.K. authorities. For more information and to determine if any of your switches are affected, facilities should consult the HSE safety alert.