Valve capacity is based on the operating conditions (liquid temperature, suction temperature, and the pressure drop across the TEV port....[yes....TEV]). In addition, the size of the valve...port size and maximum stroke. And finally, the thermodynamic properties of the refrigerant.

Due to those differences in thermodynamic properties between refrigerants, a nominal 1 ton R-502 valve is approximately a .98 ton valve when used with R-404A....very similar thermodynamic properties.

The same valve when used with R-22 has an approximate 1-1/2 ton capacity.

In addition, the pressure-temperature characterisics play a role in determining which thermostatic element the valve should use. The pressure-temperature characteristics of R-404A are close enough to R-502 to allow both to use the original R-502 thermostatic element. The Sporlan S charge is exactly the same as the R charge. Different name, same components in the element.

In the medium temperature range there is enough difference between the pressure-temperature characteristics of R-507 and R-502 that the original R-502 element doesn't work very well.

And there is substantial difference between the pressure-temperature characteristics of R-22 and R-502, R-404A and the R-22 element is not a good choice to use with any of these refrigerants.