How To Use ICOR's Pressure Temperature Chart
Every cylinder of Hot Shot-2, NU-22B, and ONE SHOT comes with a Pressure Temperature Chart (PT Chart) and Conversion Stickers inside the refrigerant box. If the PT Chart is missing, you may download and print one online HERE, or download ICOR’s Tech Tools App.
The PT Chart is used to calculate Superheat and Subcooling. The temperature column is in degrees Fahrenheit (ºF) and is the refrigerant’s temperature at a given pressure. The refrigerant columns are in gauge pressure (PSIG). Pure refrigerants like R-22, R-12, and R-134a only have one pressure at a given temperature. Blends like NU-22B, R-407C, ONE SHOT C, HOT SHOT-2 … have two pressures at a given temperature (Dew & Bubble). The Dew pressures are used to calculate superheat, the bubble pressures are left out of the temperature range from -30º to 68º because subcooling is normally not calculated at those temperature ranges, and it makes the chart less confusing.
Bubble pressures are used to calculate subcooling, the Dew pressures are left out of the temperature range of 70º to 130º because superheat is not normally calculated at those temperature ranges, and again, it makes the chart less confusing.
Example, how to calculate superheat using NU-22B:
Suction gauge pressure (psig) reads 54
Suction line surface temperature (SLST)reads 66º
Look on the PT Chart under NU-22B column go down to 54.0 Dew psig, to the left is the refrigerant temperature (RT) of 36 ºF.
Take the SLST of 66º subtract the RT of 36º equals 30º Superheat
Example, how to calculate subcooling using NU-22B:
Liquid line gauge pressure (psig) reads 229
Liquid line surface temperature (LLST) reads 90º
Look on the PT Chart under the NU-22B column go down to 229
Bubble psig, to the left is the refrigerant temperature (RT) of 110º
Take the 110º subtract the LLST of 90º equals 20º subcooling
The superheat and subcooling examples are only examples; you will need to check with the manufacture’s published literature for designed superheat and or subcooling.