• Contractingbusiness 1573 0512 Rstrefrigrdtblehagen

    Refrigerant Leaks Can Sink Your Ship

    May 1, 2012
    The transformation of the commercial refrigeration industry continues. Here, ContractingBusiness.com and Supermarket News magazines continue a series of articles based on our Second Annual Refrigeration Roundtable discussions, by refrigeration contractors and supermarket executives. Part 3: Leak Reduction

    Refrigerant leak prevention is at the top of the list of supermarket priorities. Leading refrigeration contractors also realize the service and competitive benefits that come with a “leak tight” refrigerant leak prevention strategy.

    At the second annual Contracting Business.com/Supermarket News “Refrigeration Roundtable” — held during 2011 Mechanical Systems Week in Indianapolis, IN, Sept. 21-23 — our contractor and super- market executive panelists discussed the steps they’re taking to reduce refrigerant leaks, and how the Environmental Protection Agency’s (EPA’s) GreenChill program has made a difference.

    (For show information: mechanicalsystemsweek.com)

    Many of today’s major supermarket managers are looking at leak prevention through the lens of the Environmental Protection Agency’s GreenChill program. This voluntary program was started in 2008 to assist supermarkets in reducing the amount of refrigerant leaks found in their stores’ refrigeration systems. Although the program is not open to contractors, the contracting community has become aware of GreenChill, if only because of the leak reduction mandates they’re receiving from supermarket members who are applying GreenChill methods. Four of the five supermarket companies represented in our 2011 Refrigeration Roundtable are GreenChill members.

    Steve Hagen, procurement and engineering director for Fresh & Easy Neighhborhood Market, El Segundo, CA, said the GeenChill program has raised the leak reduction bar to new levels, and has inspired store managers to do better.

    “GreenChill makes you feel bad about not doing better,” Hagen said. “So, you continuously look at ways to improve your refrigerant charge, and to reduce leaks,” he said. His efforts include annual meetings with refrigeration contractors and manufacturers, for proactive discussions on leak reduction strategies.

    “I invite manufacturers and contractors to talk about the mistakes we’ve made, how we can correct them, and what should be changed in the prototype designs. Ultimately, we spend less money because we have fewer leaks.”

    “Usually, the things you change to lower your refrigeration charge will alter your first cost. You might spend a little bit more money to attain GreenChill status—the front-end check-ups for leaks and pressures, and other methods — but you’re also going to be using less refrigerant; so you’re working to eliminate that first cost. At the end of the day, you’re doing the right thing for the environment, for lower first cost and lower lifecycle costs,” Hagen said.

    Jerry Stutler, vice president of construction and facility engineering for Sprouts Farmers Market, Phoenix, AZ, said the GreenChill program has taken the Sprouts company to new heights of efficiency.

    “We probably wouldn’t be anywhere near where we are today, if it wasn’t for the GreenChill program,” Stutler said. It’s inspired pride and competition between our stores; and everybody knows a little friendly competition will make you better. I don’t know what we’d do without GreenChill. I get a little worried over the talk of government cuts, and what might happen to GreenChill.”

    Sprouts recently won a GreenChill award for achieving an average refrigerant leak rate among its stores of 6.5%.

    “We didn’t have a lot of leaks, or many large leaks, but we kept up the pressure to improve. We met with our service providers, and made sure they were checking for leaks every time they visited the stores. They don’t leave any store if there’s a leak that needs to be repaired.”

    Sam Cantrell, a mechanical engineer for Raley’s Sacramento, CA, said the GreenChill program empowers end users to start taking inventory of “what’s going on” with their equipment, and provided an example of the value of closer scrutiny.

    “We’ve been tracking our leak rates for about 10 years, long before our involvement with GreenChill, and before all of the press attention to leak rates,” he said. “We found that a majority of our leaks were coming from small components. There’s a lot of information on the fact that leaks are found most often in brace joints and store piping; our data couldn’t be farther from that. It’s small components.”

    Cantrell added that his service on the ASHRAE Standard 17 committee — which is focused on reducing the release of halogenated refrigerants — has revealed to him the discrepancy between factory testing and real-life stresses equipment will experience once its operating in-store.

    “One of the things that’s come up several times in that meeting, is that the components that go into racks and cases are never tested in the factory to the same standards they’re exposed to during the start-up process. Between the pressure test and the evacuation test, those components, if they’re bigger than a breadbox, have never been subjected to those extemes for that amount of time.

    “So, contractors get caught in the middle,” Cantrell agreed, “because a grocery chain could very easily say ‘why is your system leaking at that point?’ when in actuality, the manifold may never have been held to a vacuum for a period of days at 500 microns or 250 microns, or whatever the end-user spec is. We’ve been beating up on contractors for years, and it isn’t even their fault.”

    Bill Almquist, a refrigeration contractor panelist, and president of Almcoe Refrigeration, Dallas, TX, — the Contracting Business.com 2009 Commercial Refrigeration Contractor of the Year — said his company is using up-to-date leak detection technology, paired with system alarms, to tightly monitor receiver levels. This enables his technicians to respond quickly to a detected liquid loss.

    “We encourage our customers to install leak detection systems even if not required by local code,” Almquist said. “We emphasize the importance of the customer’s involvement in the leak checking process by providing leak detectors to their in-house general maintenance personnel. And, using the GreenChill leak detection and installation guidelines minimizes the possibility for leaks, especially during the warranty period.”

    Almquist added that Almcoe technicians perform leak checks in customers’ stores every time they’re in the store for a service visit, and during routine periodic maintenance visits.

    He said they find that the most common cause of leaks to be from vibration, and from pipes rubbing against supports or structural steel.

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    “Mechanical joints are big leakers too,” he said. “Seals have a tendency to leak after a refrigerant retrofit, so proper procedures must be followed if you retrofit your systems to the new gases. Other causes of leaks are original equipment manufacturer (OEM) part failure and piping stress.

    Almquist said working together with the stores’ in-house teams will also lead to reduced leak rates.

    “Customers that allow us to perform timely leak checks experience far fewer leaks, and the resulting downtime is minimized, and product loss due to temperature fluctuation from refrigerant leaks are minimized. Annual leak rates are reduced, thus complying with EPA standards.”

    Bryan Beitler, vice president/chief engineer for Source Refrigeration & HVAC, Anaheim, CA, said a well-rounded leak prevention strategy starts at the installation of a new system.

    “Many of our customers are Green Chill partners, and specify that we follow those procedures,” Beitler said.

    “One must be very deliberate when going through the process, and insure that each segment of the installation has been tested individually, then as a whole prior to charging the system. The Green Chill standards mandate that systems are pressure tested to 300 PSIG for 24 hours, with +/-1 PSIG variation. Next, a triple evacuation procedure is done, with a target final vacuum of 300 microns that must hold for 24 hours.

    Beitler remarked on the importance of using proper testing equipment during construction. This equipment includes a quality high displacement vacuum pump and electronic micron gauge.

    “Source has also invested in helium leak detection technology, where we can use trace amounts of helium in the system, and a specialized sensing system to find leaks. We believe that we’ve found and repaired potential leaks that may have only been ounces per year by employing this technique. Other methods may not have picked up these small potential leaks. Installing systems with a minimum amount of flare nuts, small sensing lines, threaded fittings, Schraeder valves and other locations that have known leak potential are critical,” he said.

    Flooded Starts

    Q: What are the signs of a flooded start?
    A: Signs of a flooded start are worn or scored rods or bearing, rods broken from seizure, and an erratic wear pattern on the crankshaft.

    Q: What causes a flooded start?
    A: Flooded starts are the result of refrigerant vapor mirating to the crankcase oil during the off cycle. When the compressor starts, the diluted oil can’t properly lubricate the crankshaft load bearing surface, causing an erratic wear or seizure pattern.

    Q: What can be done to avoid flooded starts?
    A: 1) Locate the compresor in warm ambient or install continuous pump down.
    2) Check crankcase heater operation.

    Q: What are the signs of slugging?
    A: Signs of slugging are broken reeds, rods, or crankshaft, and loose or broken backer bolts, as well as blown head gaskets.

    Q: What causes slugging?
    A: Slugging is the result of trying to compress liquid refrigerant and/or oil, in the cylinders. Slugging is an extreme floodback in air-cooled compressors and a severe flooded start on refrigerant cooled compressors.

    Q: What can be done to avoid slugging?
    A: 1) Maintain proper evaporator and compressor superheat.
    2) Correct abnormally low load conditions.
    3) Install accumulators to stop uncrontrolled liquid return.
    4) Locate compressor in warm ambient or install continuous pump down.

    Copyright 2005 Emerson Climate Technologies, Inc. All rights reserved. Used by permission.