Leak rate

Leak rate is the measure of how quickly an appliance is losing refrigerant, expressed as a percentage of its full charge on an annualized basis. It is the trigger metric for the leak repair framework: for appliances holding 50 or more pounds of refrigerant, exceeding the applicable threshold creates repair obligations for the owner or operator. The thresholds depend on equipment class: 20 percent for commercial refrigeration, 30 percent for industrial process refrigeration, and 10 percent for comfort cooling and other appliances.

The calculation is performed on a rolling basis, not as a lifetime average. A shop that divides all refrigerant ever added by the appliance's age will understate the leak rate of a system whose condition is deteriorating, because early tight years dilute recent losses. The rolling method reflects the appliance's current behavior, which is what a repair obligation is meant to address. Purged refrigerant destroyed at 98 percent or greater verified efficiency may be excluded from the calculation.

Above the repair thresholds sits a disclosure obligation: an appliance that leaks 125 percent or more of its full charge in a calendar year requires a report to EPA. A system can exceed its own full charge in a year because it is repeatedly topped off as it leaks. On the exam, leak rate questions hinge on classification, on the rolling versus lifetime distinction, and on matching each number to its obligation.

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