Refrigerant pressure-temperature data
Saturation pressures come from CoolProp (MIT license), which implements published reference equations of state for pure refrigerants and mixture models for blends. For each refrigerant the build computes the bubble-point (saturated liquid) and dew-point (saturated vapor) pressure at every whole degree Fahrenheit from -60°F up to 160°F or just below the critical point.
- Gauge pressure at sea level. Tables show psig, which is absolute pressure minus 14.696 psi. Gauges read relative to local air pressure, which drops about 0.5 psi for every 1,000 ft of elevation in the U.S. Standard Atmosphere (12.23 psia at 5,000 ft), so at 5,000 ft a gauge reads roughly 2.5 psi higher than these tables for the same refrigerant temperature.
- Vacuum. Below 0 psig the tables show inches of mercury vacuum (in Hg).
- Blends. Zeotropic blends boil over a temperature range (glide), so liquid and vapor pressures differ at the same temperature. Use the vapor (dew) column for superheat and the liquid (bubble) column for subcooling.
- One refitted mixture pair. CoolProp's default interaction parameters for R-32 with R-1234yf put R-454B bubble pressures 1 to 2% above the refrigerant makers' published data. FieldCharts refits that pair's two temperature parameters to Chemours' published Opteon XL41 (R-454B) data at even temperatures and checks the result on the odd temperatures the fit never saw, where the largest error is 0.23%. The same refit moves R-452B, R-448A and R-449A closer to their own manufacturer charts. Some equipment makers' published R-454B charts run higher than the refrigerant makers' charts; for charging, the equipment manufacturer's chart governs.
- Interpolated rows. For a few blends the mixture solver does not converge at isolated temperatures near the top of the table. Those rows are filled by cubic interpolation of ln(P) against 1/T between neighboring computed points and marked with an asterisk. Tested by removing ten known points, the method reproduces them within 0.01 psi.
Validation against manufacturer charts
Before a refrigerant is published, its computed table is compared with points copied from a refrigerant manufacturer's published PT chart. A point passes if it is within the larger of 1 psi or 1% of the chart value. A refrigerant with any failing point is not published. The results are in the table below and on each refrigerant's page.
Calculators
- Superheat = suction line temperature minus the dew-point saturation temperature at suction pressure.
- Subcooling = bubble-point saturation temperature at liquid line pressure minus liquid line temperature.
- Liquid line charge = tube internal volume (ASTM B280 inside diameter) × saturated liquid density from CoolProp at the liquid temperature you enter.
- Voltage drop = 2 × K × I × L ÷ CM for single-phase and DC, 1.732 × K × I × L ÷ CM for three-phase, with K in ohm-circular mils per foot.
- Speeds and feeds: RPM = SFM × 3.82 ÷ diameter; feed = RPM × flutes × chip load.
Reference tables
Drill, thread, bolt, O-ring, wire, sheet metal and pipe tables are compiled from the governing standards or the manufacturer references that reproduce them, and each table is cross-checked by script against two independent published sources before it is committed. The sources and the cross-check result appear under each table.
FieldCharts does not publish tables from the National Electrical Code. Ampacity, conduit fill and box fill come from the code book adopted in your jurisdiction.
Corrections
If a value disagrees with a source you trust, email hello@fieldcharts.com. Confirmed errors are fixed and listed on the corrections page with the date.