A release of liquid chlorine occurred due to an incorrect operation of a liquid chlorine valve on a tank wagon. The liquid chlorine spill was discovered, and the wagon emergency stop valve was manually re-closed. The installation’s personnel were unable to start manually the safety procedures (opening of the vapour exhauster, water sprinkling), because of their need to seek shelter. The doors of the filling station building were still open, because the tightness control, which according to the standard procedure must be carried out with chlorine gas originating from the storage tank, had not yet been performed. Both on-site and off-site emergency response services were alerted. About 30-40 staff members of the establishment and employees of other companies were evacuated. This incident caused a slight poisoning of 28 persons, of whom 26 were briefly treated as in-patients in a hospital, mainly on account of the necessity of observation.

The liquid chlorine valve was activated too early: the connecting valve between the filling pipeline and the storage tank was still shut, thus the pressure surge in the filling pipeline caused the failure of the gasket on the slip-on connecting flange between the tank wagon and the filling pipeline. The plant operator will improve procedures and technical systems.