R-410A PT Chart: Pressure and Temperature, −40°F to 150°F

Enter a gauge pressure, then fine-tune it with the step buttons or the slider, and the tool returns R-410A's saturation temperature on the side you choose: Suction (vapor): dew point for the suction line, Liquid line (liquid): bubble point for the liquid line. The opposite point and the small glide separating them appear below it. With I have a set to Temperature, the tool reads the chart rows instead, and a temperature between two rows lists both. Ticking Also show °C and kPa adds metric values alongside. The table under the tool has both columns in 191 rows, one for each degree from −40°F to 150°F.

Worked example: R-410A at 75°F and at 120 psig

Show the math

The temperature box opens at 75°F, which is a row in the table, so both answers are read directly: 218.64 psig on the bubble side and 217.91 psig on the dew side. They differ by only 0.73 psi.

The pressure box opens at 120 psig, which falls between rows on both curves. Start with the bubble column: the 40°F row holds 118.79 psig and the 41°F row 121.09 psig. From the lower row, 120 psig is 1.21 psi up a 2.30 psi climb, a fraction of roughly 0.53, so the bubble temperature is 40.53°F and the tool displays 40.5°F.

The dew column runs a little lower, from 118.36 psig at 40°F to 120.65 psig at 41°F. Here 120 psig covers 1.64 psi of a 2.29 psi step, close to 0.72, and the dew temperature comes out as 40.7°F. The gap between the two rounded temperatures is the glide, 0.2°F.

A blend that behaves almost like one fluid

R-410A is a blend of more than one refrigerant, and CoolProp gives it separate bubble and dew curves. They just barely separate. Take a dew point of 40°F: the dew pressure there is 118.36 psig, and at that same pressure the bubble side reaches saturation at 39.8°F, a glide of 0.2°F. Worked the same way from every dew row in the table, the glide stays between about 0.1°F and 0.2°F from one end of the chart to the other.

Seen as pressures at a fixed temperature, the columns are 0.09 psi apart at −40°F and grow to 1.16 psi at 120°F. Compare that with the R-454B chart, where the glide at 120 psig is 2.6°F.

Because it's still a blend, the tool keeps showing both points rather than merging them. For R-410A, picking the wrong one moves a saturation temperature by no more than about two tenths of a degree.

Which column the calculator reads

Superheat is worked from the dew point, since the suction line carries vapor that has finished boiling. Subcooling is worked from the bubble point, since the liquid line carries liquid that hasn't begun to boil. The superheat and subcooling calculator opens on R-410A and applies that rule for you. It won't say what a system ought to read; that comes from the equipment manufacturer.

How this chart was made

The data comes from CoolProp 8.0.0's built-in R-410A model, evaluated once per whole degree. Every pressure is gauge pressure, found by subtracting a sea-level standard atmosphere, 14.696 psia, from CoolProp's absolute value.

For a check, seven temperatures between −40°F and 150°F were compared with Hudson Technologies' R-410A distributor chart. Hudson prints a single pressure per temperature, so each was compared with whichever column sat nearer. The biggest difference, 5.02 psi, was at 150°F, followed by 0.84 psi at −40°F; at the other five temperatures it stayed below 0.5 psi. Taken as a share of absolute pressure, every point but −40°F differs by under 1%. At −40°F the pressure is low, so the same 0.84 psi works out to about 3%. See how the charts are made for the rest of the checks.

Pressures that fall between rows are interpolated along a straight line and rounded to the nearest 0.1°F. Outside the chart's range the tool returns nothing.