Manufactures of refrigerants, controls and other suppliers distribute hundreds of thousands of pressure-temperature (P-T) charts to the trades ever year. It would be rare to find a service technician who could not put their hands on a P-T card on short notice.
In spite of wide spread availability of P-T charts, very few service technicians can us them to properly diagnose a refrigeration system problems.
The attached article will offer a refresher on pressure-temperature relationships as well as provide basic information on how use P-T, superheat and subcooling to analyze system operation and performance.
Also attached is a P-T charge that covers many common refrigerants as well as a blank form to log actually system pressure and temperatures to assist in diagnostics.
Search key words: Sub-cooling , sub-cool, subcooling, sub cooling, super heat.