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Pressure temperature chart for refrigerants

22K views 21 replies 7 participants last post by  beenthere 
As the others said, ambient temp and the PT chart don't really get used together with a refrigeration system/circuit. The only time it is really used with ambient temp, is when your checking the calibration of your gauges.

Perhaps if you explain what type of charging problems concerns you have, we can better tell you how to check charge of a system.
 
The pressure and temps on the PT charts are saturation pressures and temps. They are not suction or discharge temps or pressure. this is the pressure the refrigerant will exert at X degrees provided that both liquid and vapor are in the container(as said earlier).

The chart is used to determine the amount of subcool or superheat the system is operating at. Not what it should be operating at.

Take a new cylinder of R22, at 32°F it will have 58PSIG in it. At 83°F the same tank with the same amount of refrigerant in it will have a PSIG of 180. The reason is that it is a saturated refrigerant. Meaning that the refrigerant is existing in the cylinder as both liquid and vapor. As the refrigerant warmed up, more of the liquid boiled off to vapor, and the vapor takes up more space then the liquid did, so the pressure increased. But the total mass in the cylinder remained the same.

You may want to read up on "saturation".
 
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