What should be done to achieve accuracy when adding refrigerant to a charging cylinder?

Achieving accuracy when adding refrigerant to a charging cylinder is best accomplished by weighing it in. This method provides precision by allowing the technician to monitor the exact amount of refrigerant being added, ensuring that it meets the manufacturer's specifications and maintains system efficiency. Weighing the refrigerant helps prevent overcharging or undercharging, which can lead to system malfunctions or inefficiencies.

Filling from the liquid phase and venting off excess vapor, while relevant to refrigerant handling, do not directly ensure the accuracy of the amount added to the cylinder. Filling from the liquid phase can be beneficial for certain applications but does not provide a direct measurement of how much refrigerant is in the system. Adding at a constant pressure relates more to operational stability than to the precision of the refrigerant quantity being charged.