Death, taxes and refrigeration leaks seem to be constants in the supermarket industry.
According to the U.S. Environmental Protection Agency, supermarket refrigeration systems on average lose about 23% of their initial refrigerant charge annually to leaks resulting from tiny cracks somewhere in their labyrinth of pipes and machinery. The resulting losses have repercussions ranging from the financial to the environmental.
One approach to the leak problem is to build refrigeration systems that use less synthetic refrigerant that's bad for the environment and more natural refrigerant, like carbon dioxide, whose environmental impact is negligible even if it does leak (see story, Page 56).
But some retailers, including Giant Eagle and Farm Fresh, are intent on getting to the root of the leak problem and just running leak-tight systems, regardless of the type of refrigerant used. At the Food Marketing Institute's Energy & Technical Services Conference last month in Indian Wells, Calif., executives from those chains shared their approaches to the leak problem.
While Giant Eagle employs fairly traditional methods for containing leaks, Farm Fresh has adopted a hydrogen leak detection system that heretofore only refrigeration manufacturers have used.
Giant Eagle, Pittsburgh, is one of the best in the industry at containing refrigeration leaks. In August, the chain was recognized for the having the lowest annual leak rate — 7.8% — among the chains participating in the U.S. Environmental Protection Agency's GreenChill Advanced Refrigeration Partnership. Last year Giant Eagle shared the award with Harris Teeter as both chains held their leak rates to 10%.
Giant Eagle's refrigeration management team consists of the chain's engineering and maintenance groups and five outside refrigeration service providers, who are responsible for replacing lost refrigerants as part of their contract. “We all work as a team — that's one reason for our low leak rates,” said Cliff Timko, Giant Eagle's energy manager, who is retiring this year, at the FMI Energy Conference. Another reason, he said, is the application of infrared leak detectors in virtually all of the chain's 163 corporate stores.
Using air hoses, the leak detector draws air from between eight and 16 locations in a store's refrigeration system every 30 minutes. If it detects refrigerant above a threshold level, the device sounds several electronic alarms: One goes to a remote alarm monitoring center; another travels via a wide-area network to a refrigerant monitoring service, which in turns sends email alerts to service contractors, who send out a technician to fix the leak.
The technician fills out a tracking report describing the leak, its location, cause and remedy, and emails it to a refrigeration manager. This data is compiled in monthly reports that measure each store's refrigerant usage. “We use those reports to identify problem areas in high-leakage stores,” said Timko. Giant Eagle also tracks the performance of each of its service contractors.
HYDROGEN DETECTOR
Farm Fresh, Virginia Beach, Va., also employs infrared leak detectors, but over the past year has been using a hydrogen leak detection system to enhance its detection and prevention practices.
The system is ordinarily used by refrigeration manufacturers such as Hill Phoenix and Carrier to test equipment in the manufacturing process, noted David Morris, director of leak detection, Adixen, a division of Alcatel Vacuum products, Hingham, Mass., which provided Farm Fresh with the system.
Farm Fresh is the only food retailer currently using it, though interest among retailers was piqued at the FMI Energy Conference by a presentation given by Jonathan Perry, Farm Fresh's director of energy and maintenance, who at previous conferences has discussed HVAC and freezer-door-monitoring innovations he has brought to the chain.
Perry first heard about the eight-pound leak detector from his contacts at Hill Phoenix, who cautioned him about the cost of the system, which ranges from $5,000 to $15,000 per unit.
But frustrated by the persistence of leaks in his refrigeration systems despite the application of conventional detection tools, Perry decided to try the hydrogen detector anyway and now has three units. “It sounded like a lot of money, but with the money we lose in leaks, I thought it might not be so expensive if it helped us,” he said.
The hydrogen detector works the same as a conventional electronic leak detection tool that fills a refrigeration system with nitrogen and a trace amount of refrigerant and determines if any leaks out — except that hydrogen is used instead of the refrigerant. With its tiny molecular size, hydrogen is able to escape through smaller cracks in the system than a refrigerant could, thereby serving as a more sensitive detector of structural flaws that could later expand into larger leak-producing crevices. In terms of leak detection, hydrogen is 1,000 times more sensitive than refrigerant.
To test a refrigeration system with hydrogen, a Farm Fresh technician fills it with “Hydrostar,” a mix of 95% nitrogen and 5% hydrogen (a safe amount), under 300 pounds of pressure. The technician then uses an electronic wand and bubble solution to look for hydrogen leaks. If none are found over a period of time (at least one hour), the system is emptied and a vacuum pump is used to pull a “deep,” or almost perfect, vacuum that consistently measures less than 100 microns of pressure, which is rarely achieved with conventional methods. If that pressure holds over a period of time (up to 24 hours for a complete store), the system is deemed leak-tight.
Perry has also developed a new vacuum procedure he calls “dynamic flow” that ensures that the maximum amount of moisture is taken out of the system as the Hydrostar gas is removed, and no new moisture is introduced, among other features.
Since May 2008, Perry has thoroughly leak-tested four stores (one new store and three remodels) with the hydrogen system, identifying and repairing leaks following the installation of their refrigeration systems. None of those stores have since sprung any new leaks. “That's not typical; you usually find more leaks,” he said, adding that over time, the mechanical wear-and-tear on the system may cause some leaks.
In the first store, he had tested the refrigeration system conventionally and found no leaks, yet with Hydrostar eight small leaks were discovered in various places across the system. In one case, a bubble test revealed a leak in the compressor that flabbergasted Perry. “That was one of the things that sold me on this,” he said.
Perry has also started using the hydrogen system in other remodeled stores, in his highest-leak-rate stores, and to certify new cases installed overnight; it is now a mandatory leak detection tool for all new systems. “We're finding leaks that we couldn't find before,” he said. “And over time our leak averages have dropped.” This year the chain is averaging its best rate to date, which he attributed in part to the hydrogen system.
Given the cost of using the hydrogen system, however, it is reserved for situations “where I know there's a leak and I have exhausted all of the quick methods of finding it,” Perry said. “We've done a lot more of that lately.”
The hydrogen system has also eased the frustration of technicians who had been stymied by elusive leaks, inspiring greater confidence in leak detection technology, Perry noted.
In assessing the ROI of a $15,000 hydrogen leak detection system, Perry estimated that the system can cut the leak rate of a store by 10 percentage points. If that saves 350 pounds of refrigerant annually, the savings at $5 per pound would be $1,750 per store. “If you did four stores per year, it would pay for itself in about two years,” he noted. Other savings would include the cost of lost refrigerant, the effort to find and repair leaks, and the cost of lost product and “unhappy customers.”
Keilly Witman, manager, EPA's GreenChill program, observed that “the evidence from Jon Perry's Farm Fresh stores indicates that hydrogen leak detection systems can and do work in the field to detect leaks that otherwise are missed. It is important that the supermarket industry has a broad range of tools available to achieve leak-free refrigeration systems.”
While Perry is interested in exploring the energy-saving and leak-prevention potential of new refrigeration systems that use carbon dioxide, he is more focused on preventing leaks in conventional systems during installation and maintenance. Even the new systems will need to be leak-tight, he added. “No matter how the industry changes, building tight systems is the best approach.”