A leak of 20 kg of ammonia (NH3) occurred in a meat production plant after the bursting of 10 mm diameter pipe that ensured the return of oil from the separator to the high pressure compressor. At 7.20 am, the “NH3 detection” alarm sounded in the NH3 control unit with telephone transmission to the maintenance team manager. The machine room was shut down and its forced extraction system was switched on. The fault was observed on the control unit: Machine room alarm sensor no. 7 – 1,028 ppm of NH3′. Equipped with rubber masks, a maintenance team entered the machine room to check the source of the alarm. Coming out of the room with their cartridges saturated, at 7.30 am they confirmed the significance of the leak with the manufacturing manager so that he could alert the emergency services. One of the technicians then went to the site entrance to receive them, 2 others recovered the emergency response equipment (protective suit and SCBA).

NH3 was diffused in the fresh packaging/shipping sectors which were evacuated as a priority at 7.35 am. Two technicians wearing airtight clothing located and stopped the leak. Staff were evacuated at 7.40 am from the workshops to the rest room opposite the machine room. The leak was on a compressor which was isolated at 7.45 am. The machine room and the production rooms were ventilated at 7.50 am by opening the dock doors and vents. Firefighters monitored the change in NH3 concentration in the workshops and in the attic spaces; 200 ppm were measured at 8.15 am in the machine room and 131 ppm on the loading dock at the top of the stairs rising from this room. The firefighters did not want to leave the employees in a confined area, and asked them to leave the rest room at 8.30 am and make their way to an outside meeting point.

Two people exposed were hospitalised at 9 am for further examinations. Sectors of the plant were accessible again 1 hour later (< 5 ppm of NH3), with the exception of the fresh packaging/shipping sector (25 ppm of NH3), the access to which was only authorised by firefighters at 11 am. The pipe burst may have been related to the compressor's vibrations. The company responsible for monitoring the refrigeration installation checked it and switched it back on in the afternoon.

The early detection of the leak, followed by the emergency response with suitable resources for containing it as quickly as possible, no doubt helped to limit the amount of toxic refrigerant released into the air. The operator planned to reinforce the oil return pipe with a metal bracket and check the correct closing/sealing of the doors of the stairway between the machine room and the loading dock.