At 1 pm, in a cheese factory, 20 to 50 kg of ammonia (NH3) escaped from a refrigeration installation that had been shut down for three months and was in the process of being dismantled. After preparing the construction site, a subcontractor performing the work had to purge the installation; the unit’s compressor was started up to put the network under pressure in order to empty the gas pipes. The leak occurred in the compressor housing at the beginning of the pressure rise. While facing the control panel of the unit, the technician turned to look behind him when a jet of gas burned his neck. Fire-fighters were called in as reinforcement because of the heavy protective equipment required for the operation. The wounded person was evacuated to hospital and returned home several hours later. The emergency services using safety equipment isolated the circuits by closing several valves.
A ruptured compressor seal caused this accident. Although the technician was inexperienced for this type of intervention, he did not wait for his colleague to perform the purge. The subcontractor responsible for operations prepared a report on the accident circumstances.
The Classified Facilities Inspectorate was informed the following evening. No news article was published in the local newspaper. Given the characteristic smell of refrigerant, it would appear that the gas dispersed before arriving to nearby housing, as no complaint was recorded by the factory or the authorities. However, two people remained confined for 30 min.
According to the operator, internal safety procedures worked well. The maintenance department responded effectively and the equipment in place proved to be useful; however, the location of the self-breathing apparatuses had to be reviewed to increase their efficiency.
The installations involved were soon to be changed to improve performance while reducing the required amount of NH3. A new safety report will include an assessment of the new impact distances in case of incident, as they were currently set at 1 500 m.
