INNOVATION May-June 2019

F E A T U R E

AMMONIA AND ITS DANGERS Ammonia (NH 3 ) is a nitrogen- hydrogen compound that occurs naturally in trace amounts, but is caustic and hazardous in concentrated form. It is often used for industrial refrigeration for its vaporization properties and low cost. Ammonia’s relatively high liquid expansion coefficient means that liquid ammonia should never be trapped inside a vessel or between valves without a significant portion of vapour volume present to allow for expansion. With small temperature changes, trapped liquid ammonia can cause a rapid and significant pressure increase. Cold liquid or vapour ammonia leaked into atmospheric environments will quickly expand into the available space. A leak or uncontrolled release poses an immediate danger. Exposure to ammonia vapour can cause severe injuries, up to and including death.

18 recommendations to improve the safety of refrigeration systems and prevent ammonia releases. The recommendations target various stakeholders, including refrigeration plant owners, maintenance contractors, training providers, municipalities, and the Canadian Standards Association. These recommendations seek to improve: • training of owners representatives, operators and mechanics; • owner maintenance programs and organizational design; • identification of leak hazards and professional disclosure of such hazards; • secondary coolant system configuration and construction in anticipation of refrigerant leaks; and • public transparency and a culture of openness around technical system safety.

potential implications of operating a leaking chiller, but did not seek the advice of a professional engineer. Ng says that Technical Safety BC will be working to connect the network of professional engineers to owners, operators, and mechanics of regulated equipment, to help facilitate and encourage those essential conversations. “Whatever the age of a plant,” said Ng, “professional engineers play a crucial role in helping anticipate the operating decisions that contribute to failure and implementing prevention strategies into design, configuration, operating instructions, caution signage and maintenance programs.” Safety is a shared responsibility, he said, affirming that everyone—owners, designers, maintenance contractors—are “all accountable to learn from failures in our safety system so we can strengthen our prevention strategies.” RECOMMENDATIONS FOR PREVENTION Following the fatal incident in Fernie, Technical Safety BC released

With both the incidents in Fernie and Langley, workers configured the systems in a way that proved hazardous while troubleshooting and responding to abnormal performance. It’s a sobering reminder of the importance of systems being engineered to “fail safe.” In these circumstances, getting the assistance of professional engineers could be key to keeping such facilities safe. Technical Safety BC is an independent, self-funded organization that oversees the safe installation and operation of technical systems and equipment across the province. In addition to issuing permits, licenses and certificates, Technical Safety BC works with industry to reduce technical safety risks. For more information, visit technicalsafetybc.ca .

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John S. Haythorne P.Eng D +1 604 691 6456 john.haythorne@dentons.com Jana Mansour D +1 604 691 6421 jana.mansour@dentons.com

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