In a chlorine manufacturing unit, an explosion occurs in the room of the electrolysis cells. The accident occurs during the start-up phase of the unit, it is due to the presence of hydrogen in the chlorine collector of the cells. An amperage error (2000 A instead of 0) during the initiation phase is at the origin of the presence of this gas.The collector was destroyed and the chlorine spread in the workshop. The month, day and place of the accident are not specified.

At about 9:50 a.m., a lightning strike ignited hydrogen exiting a stack in a chemical factory. This hydrogen, produced by the chlorine electrolysis cells, is conveyed to the stack when the manufacturing shop that consumes it is shut down. The internal emergency plan was activated. The electrolysis chain was put into minimal operation mode. Nitrogen and steam were injected into the stack, which was cooled by in-house first responders. The situation was brought under control at 10:30 a.m.

The event occurred at the chlorine drying towers. The towers, made of PVC, exploded suddenly and violently in a mercury amalgam cell chlorine plant. Because of failure of the electrical power system a circuit breaker tripped out the mercury pumps stopped and the steel bottom plates in the cells became exposed. The alarm did not work since both the AC power supply to the mercury pumps and that for the alarm system were taken from the same source. Meanwhile the DC power and brine supply to the cells were not interrupted.

Employee #2 was using a torch to cut a U-bolt on the bypass piping next to a brine surge tank that potentially contained hydrogen gas in a vapour space in the upper portion of the tank. His job was to remove and replace the brine line that was connected to the top of the tank. Just before the accident, Employee #1 was on top of the tank unbolting the brine line. He was launched into the air by an explosion and struck against some piping or other structure, He was killed. Employee #2 was struck by piping and knocked backward. His head struck a curb and he was injured.

Failure of a strainer allowed sand from brine filters to get into mercury cells in a chlorine plant. It appears that the sand obstructed flow and caused excessive hydrogen generation. An explosion occurred in the chlorine collection system.

"A chlorine suction pump failed on a sodium hydroxide electrolysis unit.Recovery operations were carried out including nitrogen purging of hydrogen piping and air purging of chlorine piping before starting to add chlorine into the electrolysis vessel. A sudden explosion occurred about 40 minutes later at a chlorine chilling tower and chlorine transfer pipeline. The cause of the incident was a leak through the valve on the chlorine pipeline which was supposed to be closed after the air purging.

A number of minor explosions occurred in the interrupter pot on a chlorine cell. No injuries or damage were reported.No previous explosion shad occurred which was taken to indicate that hydrogen concentration within the pot was not normally within flammable limits. The ignition was believed to have resulted from the detachment of the dispersing tray in the pot, the resultant lack of a controlled break in the conductive sodium hydroxide stream leading to the release of sufficient electrical energy to ignite the flammable gas mixture.

In a plant manufacturing chlorate products, a hydrogen leak occurred via the water drainage outlet onto the factory floor. Pressure in the hydrogen line increased because the hydrogen pipes were filled with water. The situation was rectified by shutting down the process, draining the pipes and by redirecting the hydrogen flow.CAUSE: The root cause may be deemed to be insufficient level of automation because a selection permitting human error had been left in the process.

An explosion occurred in the hydrogen washing tower of a chlorate plant caused by the breaking of the rupture diaphragms on the tower cover. The discharged hydrogen ignited, causing a minor leakage of hydrochloric acid in the hydrochloric acid top container above it and the related pipes.The explosion was preceded by an abrupt reduction in the electrolysis flow resulting from a rectifier malfunction and operation at low flow density. This caused a significant increase in the oxygen level in the hydrogen gas.

An explosion occurred at a chlorine production plant during the restart of the installation. An hydraulic syphon had probably been blocked by fire extinguishing products following a previous fire on the hydrogen exhaust system. While restarting the chlorine production unit, the hydrogen pressure started to increase, allowing hydrogen to permeate through the electrolyzer membrane into the chlorine compartment. The chlorine /hydrogen mixture then entered the chlorine drying unit before exploding. The explosion was probably initiated by a discharge of static electricity or UV radiation.