How many pounds of refrigerant is the pressure enthalpy (PE) chart based on?

The pressure enthalpy (PE) chart, commonly utilized in HVAC/R applications, is typically based on a refrigerant measurement of 1 pound. This standardization allows for a consistent relationship between pressure, enthalpy, and specific properties of the refrigerant being analyzed. By utilizing 1 pound as the reference, technicians and engineers can easily interpret the chart for calculations related to refrigeration cycles, enabling them to determine conditions such as superheating, subcooling, and energy changes in the refrigerant as it undergoes phase transitions.

Using a consistent unit of 1 pound simplifies the calculations and allows the user to scale up or down to the actual refrigerant charge in a system, facilitating the practical application of the chart. In contrast, other quantities like 2, 5, or 10 pounds complicate the interpretation and usage, as they would require additional conversion factors to apply the findings to real-world systems.