A recent fatal accident, as well as reviews of previous problems, emphasized the critical importance of proper training, experience and clear-cut procedures when conducting repairs of ammonia refrigeration systems, leading industry observers said.

Often repairs must be done in time-critical situations, and technicians must resist pressures to take short cuts, they said.

In October, three men died at an ice skating rink in Western Canada while completing emergency repairs to the rink’s refrigeration system. Although the investigation is ongoing, and no formal results have been released as to the cause, the tragedy is a reminder of the critical importance of proper training and experience, and the need to establish clear cut procedures when preparing equipment for maintenance or conducting line breaking operations.

“While we don’t want to speculate on the reason for the accident in Canada, unfortunately, the industry has incurred many serious accidents during emergency or even normal repairs or line breaking where people simply didn’t follow the appropriate or reasonable safety practices,” said Peter Jordan, Senior Principal Engineer, MBD Risk Management Services, Inc.

In some cases, pressure from production personnel to bring the system back online results in shortcuts. “They’re down for maintenance for the weekend, they shut off the storage freezer, and now it’s getting warm because they’ve been working on the system for two days,” said Bob Czarnecki, former program manager of refrigeration at Campbell Soup Company and current chairman of the IIAR Standards Committee. “They feel like they need to get the system back online, so they look at an isolation valve where they can’t stop it from leaking through, for example, and they decide to blow the ammonia out a different way or put on a mask and just weld it.”

There are four critical elements to safely operating and maintaining an ammonia refrigeration system, Czarnecki said. It begins with training. With training comes knowledge, and in time, experience follows. Once those three core elements are established, the importance of adhering strictly to established procedures is understood.

Training is available through a variety of sources. The International Institute of Ammonia Refrigeration offers a complete suite of design and safety standards, video instruction and other technical publications to provide regulatory and safety guidance for ammonia systems. In addition, its Academy of Natural Refrigerants will soon introduce a new certificate course curriculum designed to provide personnel working in the industry with comprehensive training in ammonia systems. The “Academy of Natural Refrigerants Specialist” (ANRS) certificate will enable engineers and operators to expand their professional credentials and training in three major areas of standards, ammonia safety tracks and basic engineering courses. The Refrigeration Engineers and Technicians Association (RETA) also offers courses to provide operators and technicians with specific training for ammonia systems from introductory to advanced levels of certification.

“A person who does not have the knowledge or experience, or is not familiar with operating procedures shouldn’t touch an ammonia refrigeration system,” Czarnecki said.

Line breaking, which is the process of opening the system to the atmosphere usually for maintenance or system modifications, is one of the main causes for ammonia incidents when executed improperly, Czarnecki said. “Following the line-breaking procedure is very important because it gives you a step-bystep process that ensures a pipe or other piece of equipment is free of ammonia before you work on it,” he said. “But that can take days, and that’s where the danger of shortcuts come in.”

Before undertaking a line-breaking procedure, it is important to isolate the specific area of the system to be worked on, and determine a safe way to remove the ammonia before beginning the maintenance operation. Otherwise, incidents can take place, such as one reported a few years ago when a small pressure vessel needed to be replaced. “It was on a platform on the roof, with pipes attached to the vessel and ammonia behind that at high pressure,” Czarnecki said.

“They should have blanked off all the valves that were being disconnected from the vessel and made certain the valves behind it were closed. But they didn’t do that. Workers were standing on the pipes, and one worker stood over a valve handle and twisted it, and all this ammonia came flying out. A worker was seriously burned, and it was all because they didn’t follow the proper procedures to make sure nothing could come out of that pipe.”

Jordan and Czarnecki recommend that procedures be thoroughly reviewed before beginning maintenance operations. “Go through it step-by-step, and then make certain you follow the procedure exactly as you laid it out,” Czarnecki said. “People can become complacent. They just think they’re going to change a relief valve, for example, when what they should first do is sit down with their supervisor or contractor and detail exactly what they are going to do. Even though it sounds routine, you should still go over each and everything when opening up the system and exposing yourself to ammonia.”

In the end, regardless of the size of the system or the engineering controls in place, the safety of the system ultimately depends on the knowledge of the people who operate and maintain it, and the assurance that they will follow proper procedures, avoiding shortcuts that could lead to incidents.

“The moment you take shortcuts you’re in trouble,” Jordan said.