A 10 to 20-kg leak of refrigeration ammonia (600 kg of NH3 on hand) in a gaseous phase occurred at 8:15 am inside the refrigeration compressor room at a brewery. The operator’s workforce had been well trained and miscellaneous emergency response equipment was available, yet emergency services were still notified out of precaution.

A safety perimeter was set up and 2 neighbouring companies evacuated (100 personnel in all). NH3 emissions could be stopped by closing the group’s shutoff valves less than 1 hr after the leak started. All evacuees were allowed to return to work at 9:30.

Initially ascribed to a joint defect, this leak was in fact triggered after a break in the 15 mm-diameter pressure balance tubing. The installation was verified, and the defective compressor was restarted the next morning. The causes and circumstances of the pipe break were analysed. Several technical measures were subsequently implemented, including: improvement in valve and NH3 pipe referencing, and verification of good working order of smoke exhausts (one of which would have served for added ventilation, yet was inoperable).