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R-454B PT Chart (454B Pressure Temperature)

Look up R-454B liquid and vapor saturation pressures for a temperature, or the temperatures for a gauge reading.

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This R-454B PT chart (454B PT chart) lists the liquid and vapor saturation pressures of R-454B at every temperature. The R-454B PT chart is a free calculator that converts an R-454B temperature to its saturation pressure, or a pressure back to a temperature. It runs in your browser, needs no sign-up, and uploads nothing. Choose R-454B, pick the conversion direction, and enter one value to get a pressure-temperature table with liquid (bubble point) and vapor (dew point) readings. R-454B is an A2L blend of R-32 and R-1234yf that replaces R-410A in many new US residential air conditioners and heat pumps. Because it is a blend with a small temperature glide, you need both columns. Use this r454b pressure temperature chart to check your gauges, or to support quotes and service records.
454b pt chart example

How to use the R-454B PT chart

  1. Open the Refrigerant drop-down and select R-454B.
  2. Open Convert and choose Temperature → pressure to find the pressure at a known temperature, or Pressure → temperature to find the temperature at a known pressure.
  3. Enter the Saturation temperature if that field appears in your mode.
  4. If the Gauge or absolute pressure field appears, choose the unit that matches your reading: psig, kPag or barg for a gauge, or psia, kPaa or bara for absolute.
  5. Set Chart units to °F and psig, °C and bar (gauge), or °C and kPa (gauge).
  6. Read the result rows. Use Liquid pressure (bubble point) for condenser and subcooling readings, and Vapor pressure (dew point) for evaporator and superheat readings.
  7. Check any warning above the result. A negative gauge value means the pressure is below atmospheric.
  8. If needed, open More options to set the Chart table step or the Altitude above sea level. Leave altitude blank at sea level.

The example buttons above the form load sample conditions so you can see how a result is laid out. Copy result copies the result lines with a link. Copy link stores every input in the page address, so the same calculation reopens later. Print / save as PDF includes inputs, results, steps and the date. Reset restores the starting example.

How do you read a PT chart?

A PT chart lists the saturation pressure for each temperature: the pressure at which the refrigerant boils or condenses at that temperature. To read it, find the temperature in the table, then read the pressure in the same row. For R-454B at 70 °F, the chart lists 192.3 psig on the liquid column and 183.9 psig on the vapor column.

The chart temperature is the real refrigerant temperature only where liquid and vapor are both present, such as in the evaporator or condenser. In a superheated suction line or a subcooled liquid line the pressure is still about the evaporator or condenser pressure, but the pipe temperature is not the chart temperature: the difference between the two is the superheat or the subcooling. Reading the other way works the same way. Find the pressure in the table and read the temperature in the same row. At 110 psig, R-454B shows 38.52 °F on the liquid column and 41.19 °F on the vapor column.

What is the difference between bubble point and dew point?

The bubble point is the condition where the first bubble of vapor forms as a liquid is heated. The dew point is the condition where the first drop of liquid forms as a vapor is cooled. A pure refrigerant has one saturation pressure at each temperature, but R-454B is a zeotropic blend, so these two points separate. At the same temperature, the liquid (bubble) pressure is higher than the vapor (dew) pressure.

The gap comes from the blend’s components. R-32 is more volatile than R-1234yf, so the vapor and liquid phases have different compositions as the mixture changes state. This is the temperature glide. The glide is small for R-454B, but it is large enough to affect readings. At 110 °F, the calculator gives 348.6 psig liquid and 336.3 psig vapor, a difference of 12.3 psi. The same difference shows in the Bubble minus dew pressure result row.

For field readings, use the dew (vapor) value for superheat, which is measured on the vapor side of the evaporator. Use the bubble (liquid) value for subcooling, which is measured on the liquid side of the condenser. Using the wrong column can give an error of a few degrees or psi, which is why the tool shows a warning when a blend is selected.

Sources

Data and methods used by this calculator (checked October 2026):

Worked examples

InputResult
R-454B, 40 °Fliquid 113.2 psig, vapor 107.5 psig
R-454B, 110 °Fliquid 348.6 psig, vapor 336.3 psig
R-454B, 110 psigliquid 38.52 °F, vapor 41.19 °F
R-454B, 5 °Cliquid 7.955 barg, vapor 7.557 barg

Calculated by the tool above with these values.

Frequently asked questions

Is a PT chart in psig or psia?

The chart uses psig by default, which is gauge pressure: the reading relative to the surrounding air. Psia is absolute pressure, and at sea level it equals psig plus 14.696. Choose the unit in the Gauge or absolute pressure field so the result matches your gauge or your calculation.

What is the pressure of R-454B at 70 °F (standing pressure)?

At 70 °F, the chart lists 192.3 psig on the liquid (bubble) column and 183.9 psig on the vapor (dew) column. A system that has sat idle at 70 °F should read within that range. A reading well outside it is worth checking, along with the gauge itself.

What should R-454B pressures be when running?

The chart does not give a target running pressure, because running pressure depends on the evaporator and condenser temperatures in each system. As reference values, the saturation pressure at 40 °F is 107.5 psig on the vapor side, and at 120 °F it is 398.6 psig on the liquid side. For target values, use the equipment manufacturer’s charging and performance data, since blend values can differ from a manufacturer’s chart by 1–2 psi.

Why are R-454B pressures lower than R-410A?

R-454B pressures run a little lower than R-410A at the same temperature. Use R-454B data when you charge, diagnose or compare readings on an R-454B system. Using an R-410A chart on R-454B will give misleading targets.

Does altitude change the result?

Yes. Gauges read relative to local air pressure, and air pressure drops with altitude. Enter the altitude above sea level under More options and the chart accounts for it. Leave the field blank at sea level.

Can I use these results on a quote or service record?

Yes. Results, charts and printouts can be used freely in commercial work such as quotes, proposals, reports and service records, with no attribution needed. The calculation runs in your browser and nothing is uploaded. Each result is for estimation, so verify critical designs against the applicable standard.