CANADA: A Canadian safety authority is urging system operators to use licensed refrigeration contractors when performing work on ammonia systems following a fatal leak last year.
The incident occurred during the dismantling of a refrigeration system at the Arctic Glacier ice facility in Kamloops, British Columbia. The report by independent safety organization Technical Safety BC describes the release of a “significant amount” of ammonia, resulting in the death of an employee at the facility and the hospitalization of three other workers. Neighboring businesses were also affected by the leak and were evacuated. An additional fourteen people experienced respiratory problems from inhaling ammonia.
The main cause of the incident was found to be failure to remove ammonia from the refrigeration system prior to disassembly. Although no qualified refrigeration mechanic was present during the disassembly, those who performed the work understood that the system had been previously emptied.
“Our safety system is built on the foundation of ensuring that work associated with hazards is only done by people with the necessary skills and knowledge,” said Jeff Coleman, director of technical programs for Technical Safety BC.
Misunderstood
On May 26, 2022, a team was in the process of hacking and disassembling two separate ammonia refrigeration systems, referred to as P24 and P34 in the report, which had been shut down in 2015.
Those present understood that ammonia had previously been removed from both systems. During the removal of a section of the P34 system containing a receiver and compressor, a protruding valve handle from the frame was identified as a possible cause of problems with the assembly process.
One of the individuals turned the handle on the valve, which resulted in a large release of ammonia. The individual who turned the handle was sprayed by ammonia and moved further into the building. The remaining crew members evacuated through a nearby open bay door. The person who opened the valve was removed from the building and pronounced dead following the incident.
“Prior to the incident, workers unfamiliar with ammonia relied on the guidance of previously qualified refrigeration mechanics. This resulted in work continuing when it likely would have stopped,” the report states.
“Safe dismantling of an ammonia system requires that the system be evaluated and that ammonia and oil be removed prior to any disassembly work. Removing ammonia and oil from a refrigeration system is a regulated job that requires the knowledge and skills that a licensed contractor brings along with qualified refrigeration mechanics,” she adds.
Earlier version
An ammonia release had already occurred the day before the fatal incident when one of the installers released ammonia while cutting a pipe during disassembly of the separate P24 system.
Despite those present concluding that only “residual” amounts of ammonia remained, the subsequent purge in the parking lot is believed to have lasted approximately 16.5 hours.
Even after the purge occurred, the Technical Safety BC investigation found that approximately 100 lb (45 kg) of liquid ammonia was still present in the P24 system.
In addition, the P34 receptor was visually evaluated and incorrectly concluded not to contain ammonia.
In total, between May 25 and 26, up to 1,000 lbs. (454 kg) of ammonia were dissolved in water and released directly into the facility parking lot from the P24 system.
During the fatal incident on May 26, 2022, between 610 kg (1,345 lb) and 726 kg (1,600 lb) of ammonia were released as a vapor directly into the atmosphere from the P34 system.
“Only those with the necessary skills and knowledge should engage in hazardous work activities,” says Technical Safety BC. “This principle applies throughout the life cycle of regulated systems, including the decommissioning and decommissioning stage. Licensed contractors must validate that ammonia and oil have been removed from a system and that the equipment is ready for disassembly and transport.”
The full report is available here.
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