New US rules allowing greater charge sizes of hydrocarbon refrigerants in new domestic refrigerators and freezers will enter into force on September 7.
The new rules, published in the Federal Register today, are based on UL 60335-2-24 and allow charge sizes of up to 150g for the flammable refrigerants isobutane, propane and R441A in each separate refrigerant circuit. R441A is a blend of ethane, propane, butane and isobutane.
Only 57g of refrigerant was allowed under the previous standard, a charge size considered too small to allow cost effective and energy efficient manufacturing.
While other countries have been using hydrocarbon fridges for over a decade, US consumers have continued to purchase around 12 million new fridges a year using R134a. It is estimated that if the US follows the rest of the world in eliminating R134a in domestic fridges, it could avoid emissions of up to 3.7 million tonnes of direct CO2 equivalent annually.
In addition to the increased charge size, UL Standard 60335-2-24 requires tests to ensure that any leaks will result in concentrations well below the LFL, and that potential ignition sources will not be able to create temperatures high enough to start a fire. Passing the leakage test ensures that refrigerant concentrations in the event of a leak do not reach or exceed 75% of the LFL inside any internal or external electrical component compartments.
