HVAC PT Data

Pressure-temperature charts, field calculators and refrigerant data for HVAC/R technicians

PT data: CoolProp 8.0 equations of state, US units

Field guides

Reference guides on the fundamentals every refrigerant page relies on: how to read a PT chart correctly (bubble and dew columns, vacuum, elevation), the GWP chart that decides which refrigerants are allowed in new equipment, lubricant types and compatibility, evacuation to a micron target with a decay test, nitrogen pressure testing and purging, EPA Section 608 certification, the recovery procedure and cylinder rules, and how to identify an unknown refrigerant.

The guides are refrigerant-agnostic and link to the profiles and calculators where a specific value applies. Procedures follow the manufacturers' installation instructions they cite; when your equipment's manual gives a different value, follow the manual.

  • How to read a PT chart

    Find the gauge pressure in the chart and read the saturation temperature next to it. On blends, use the dew column for suction and superheat and the bubble column for liquid and subcooling. The chart only describes refrigerant that is boiling or condensing, and its psig values assume sea-level air pressure.

  • Refrigerant GWP chart

    GWP compares how much heat a gas traps over 100 years against the same mass of CO2. US rules use the IPCC AR4 values in 40 CFR 84 Appendix A, so R-410A is 2,088 and R-454B is 466 (EPA's own calculation gives 465). Blend GWP is the mass-weighted sum of its components.

  • Refrigerant oil types

    CFCs and HCFCs such as R-12 and R-22 run on mineral oil or alkylbenzene. HFCs and HFO blends such as R-410A, R-454B and R-404A run on POE, with PVE in some compressors. Automotive R-134a and R-1234yf use PAG. The compressor nameplate or the compressor maker's oil list always decides.

  • Evacuation and microns

    Pull the system down to the manufacturer's micron target, isolate the pump, and watch the micron gauge. Targets in current manuals run from 350 to 500 microns, and the pass rule differs, from holding 500 or less for 15 minutes (Rheem) to no rise above 500 within one minute (an R-454B OEM manual).

  • Nitrogen pressure testing and purge brazing

    Braze with a small flow of nitrogen, then pressurize the line set and indoor coil with dry nitrogen to the pressure the installation manual gives, never above it, and hold. Rheem's R-454B manual sets 500 psig maximum for at least 15 minutes; another R-454B OEM manual uses 250 psig, with the nameplate low-side design pressure as the minimum. Evacuate only after the system holds.

  • EPA Section 608 certification

    Section 608 certification is required for anyone who opens a refrigerant circuit on stationary equipment. Type I covers factory-sealed small appliances, Type II medium-, high- and very-high-pressure equipment, Type III low-pressure chillers, and Universal all three. The certificate does not expire, and since January 1, 2018 it covers HFC and HFO refrigerants as well as CFCs and HCFCs.

  • How to recover refrigerant

    Confirm the refrigerant, prepare an evacuated cylinder rated and labeled for it, recover liquid first and then vapor with a certified machine, and pull the system to the level in 40 CFR 82.156 Table 1. For a high-pressure system under 200 lb that is 0 in Hg. Recovered refrigerant can go back into the same owner's equipment, but it can only be sold for reclamation or destruction.

  • How to identify an unknown refrigerant

    Read the equipment nameplate and the cylinder label; cylinder paint and service ports tell you almost nothing. A standing pressure check on an idle, equalized system or a cylinder at a measured temperature can rule refrigerants out, but it cannot prove what is inside. For certainty, use a refrigerant identifier. Treat anything unconfirmed as mixed: recover it into its own cylinder and send it for reclamation.