A technician removes a bolt-on piercing valve after finishing recovery on a refrigerator. Why is leaving a piercing valve on the system long-term discouraged?

Explanation

Bolt-on saddle piercing valves rely on a rubber gasket that can dry out or degrade over time, creating a slow leak. Because avoidable leaks release refrigerant and waste charge, these valves are meant for temporary access. Permanent access is better made with a properly brazed process tube or a soldered access fitting.