Pollution
Humain
Environnement
Economique

After 11:55 am and over a period of 2 h, 100 to 200 kg of ammonia (NH3) escaped from the refrigeration installations that were being renovated in a slaughter house. Fire-fighters were alerted. The 200 employees were evacuated, and one of them who suffered respiratory failure was hospitalised for 72 hours. Maintenance staff wearing gas-tight protective suits stopped the compressors and closed the distribution valves. One of the operators involved, who received minor burns to his forehead above his mask, returned to work the next day. To reduce the quantity of NH3 used from 4,300 kg to 125 kg, the operator decided to install a glycol water-based refrigerant circuit. The specialist company that had to modify the unit appointed a subcontractor to install the new glycol water circuit pipes. On the day of the accident and although he was not supposed to work on the existing networks, one of the subcontractor’s employees, who wanted to make it easier to install a new pipe, decided to cut a pipe that he thought was not in operation. This pipe was in fact connected to the refrigerant circuit of the establishment’s cutting workshop. The amount of NH3 lost corresponded to the volume of refrigerant contained in the cut pipe. The fire-fighters set up a water curtain to limit the diffusion of the cloud of NH3 and aerate the premises via mechanical then natural ventilation. Following the intervention, 609 mg/l of ammoniacal nitrogen were released into the waste water treated by the municipal treatment plant.