Which of the following actions triggers the requirement to calculate a leak rate when adding refrigerant to an appliance containing 50 or more pounds of an ozone-depleting refrigerant?

The requirement to calculate a leak rate comes into play specifically when topping off a system that contains 50 or more pounds of an ozone-depleting refrigerant. Topping off generally indicates that an appliance is being filled or supplemented with refrigerant, which can highlight the need to determine if the system has an ongoing leak.

Regulations dictate that if a system requires additional refrigerant, it could be indicative of a leak, necessitating a leak rate calculation to ensure compliance with environmental standards aimed at minimizing the release of ozone-depleting substances. This proactive measure helps in monitoring and maintaining the integrity of the refrigeration system.

Scheduled maintenance, refrigerant recovery, or changing the appliance doesn’t inherently trigger the same requirement. Maintenance activities are typically routine and may not involve verifying refrigerant levels unless there is a known issue. Refrigerant recovery represents an action where refrigerant is being removed from a system, rather than added, and does not require a leak rate calculation in the context of adding refrigerant. Changing an appliance would generally imply a complete replacement, and the focus would shift to the new unit's compliance rather than assessing leakage in the existing system.