Mill Valley, California — Supermarket refrigeration is one of the leading sources of super-polluting hydrofluorocarbon refrigerant (HFC) emissions, according to the North American Sustainable Refrigeration Council (NASRC).
As a result, NASRC released its free Leak Reduction Initiative guide which outlines major sources of refrigerant leaks in existing refrigeration systems. Additionally, it establishes proposed equipment specification measures to resolve these issues and minimize greenhouse gas (GHG) emissions from refrigerant leaks.
NASRC states that HFC refrigerants used in supermarket refrigeration systems leak on average 25 per cent of the refrigerant charge annually. This results in a climate impact from supermarket and grocery store refrigerant leaks estimated to be 55 million metric tons of carbon dioxide equivalent (MTCO2e) annually or more than half a billion MTCO2e over 10 years.
Thicker wall tubing takes longer to corrode, leak due to fatigue, and wear out, adding years ofleak-free service
Through its guide, NASRC was able to gather from retailers the top leak issues across four categories. These included cases and fixtures, machine rooms and racks, condensers, and connecting piping. Based on the retailer data, leaks in cases and fixtures, and machine rooms and racks accounted for over 80 per cent of leak incidents.
Going into further detail, leaks occurring in cases and fixtures included, evaporator leaks due to tubing failures, access valves used for servicing, lines rubbing together either through contact and vibration or through thermal expansion, and electrical wiring failure causing leaks.
Leaks occurring in the machine room and rack included, compressor vibration relative to the rack structure, causing tubing failure (stress), leaks from high side control lines, mechanical fitting connections, access valves used for services such as rotolock valves and stem packing leaks, and tubing vibrating against dissimilar metals.
Over time rotolock mount nut loosensfrom thermal cycling and compressor vibration
Leaks occurring at the condenser featured tube sheet leaks at condensers and fan breakage/motors falling into the coil and causing leaks. Lastly, leaks occurring on connecting pipers featured corrosion and abrasion.
In response to the leak issues, NASRC retailers formed a committee to proactively develop best practices and standard equipment specification measures to reduce leaks over the refrigeration system’s life.
The committee identified six measures to reduce leaks.
1. Require 45 bar working pressure (Type K copper) in a display case and walk-in coils, all piping, and on racks
2. Any tubing or part that carries refrigerant cannot come into contact with any other metal
3. Eliminate any flare fittings on copper tubing
4. Eliminate rotolock fittings
5. Add a temporary pressure gauge or indicator to visually confirm that the system is pressurized after arriving on site
6. Specify better CO2 relief valves
For more information regarding the free guide, visit the Leak Reduction Initiative guide.