"The U.S. Chemical Safety and Hazard Investigation Board (CSB) issues this Safety Bulletin to emphasize the importance of installing, testing, and maintaining chlorine detection and emergency shutdown devices on chlorine railcar transfer systems. This bulletin compares two chlorine releases investigated by the CSB. In both, a railcar unloading hose failed and chlorine was released. In the first incident, an emergency shutdown system malfunctioned, resulting in a release of 48,000 pounds of chlorine and a significant community impact. In the second, the emergency shutdown system worked to minimize the release, and the community was not impacted."
Report No. 2005-06-I-LA
U.S. Chemical Safety and Hazard Investigation Board: http://www.csb.gov/