After unscheduled maintenance to drain oil from the pumps, the refrigeration system was noted to be slow to return to performance and oil contamination of some system evaporators was suspected. The responding refrigeration mechanic stated he attempted to improve system performance by closing valves to generate pressure within an evaporator to move or dislodge potentially trapped oil. The pressure rose very rapidly once the evaporator was isolated between closed valves, breaking a pressure gauge needle (photo 3) and rupturing the evaporator (photos 1 and 2). An estimated 485 to 1,500 lbs of ammonia was released from the ruptured evaporator into the freeze-drying production chamber.
Ruptured refrigeration evaporator releases ammonia resulting in extensive area evacuation