INNOVATION May-June 2019

F E A T U R E

PRESSURE BUILDUP Lessons from Uncontrolled Ammonia Releases

LAURA MCLEOD Technical Safety BC

I n October 2018, more than 100 businesses in a Langley Township business park were forced to evacuate for 48 hours due to an uncontrolled ammonia leak. A nearby pet food manufacturer’s refrigeration system had experienced a mechanical failure: a rupture of the system evaporator and release of ammonia. Luckily, there were no injuries. According to provincial safety regulator Technical Safety BC, this ammonia release—and another in Fernie a year earlier that led to multiple fatalities—highlight opportunities for professional engineers to provide input and advice throughout the full lifecycle of refrigeration equipment, so that similar

refrigeration system was slow to return to expected performance; oil contamination of some system evaporators was suspected. In an attempt to improve system performance, the mechanic closed valves to generate pressure within an evaporator in an attempt to move or dislodge potentially trapped oil. Once the evaporator was isolated, pressure between closed valves rose very rapidly, breaking a pressure gauge needle and rupturing the evaporator. A substantial amount of ammonia was then released from the ruptured evaporator into the freeze-drying production chamber. The ammonia escaped the chamber—which wasn’t designed to contain ammonia—into the atmosphere. As the regulatory body charged with the oversight of refrigeration systems in BC, Technical Safety BC investigated the incident to find the root causes. As with many incidents involving complex technical systems, there was a mix of technical failures

occurrences can be prevented. WHAT HAPPENED IN LANGLEY?

On the day of the incident, a refrigeration mechanic drained oil from the pumps during an unscheduled maintenance call. The

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