This calculator requires the use of Javascript enabled and capable browsers. This script determines the gas pressure based on temperature of R134a refrigerant. Production of chlorofluorocarbons (CFCs) has been phased out. Environmentally acceptable replacement compounds are therefore needed for use in existing medium and low temperature refrigeration applications. Refrigerant R134a or HFC-134a was developed to meet these needs. Refrigerant R134a or HFC-134a is a commercially available hydrofluorocarbon (HFC) refrigerant for use as a long-term replacement for R-12 in new equipment and for retrofitting medium temperature CFC-12 systems. This refrigerant takes a significant step forward in environmental protection by achieving an ozone depletion factor of zero. It is used in both automotive and commercial air conditioning applications. It is the common phase "environment friendly" replacement for R12 but does require system retrofit modifications. Enter the temperature in either F or C degrees and the returned result is the alternate temperature and determined pressure in Barg and psig. Barg is the gauge read pressure. The term gauge signifies that the pressure has been read from a gauge that actually measures the difference between the pressure of the fluid or gas and the pressure of the atmosphere. Psig is equal to psis at sea level (14.7 psi). Psig (inches of mercury) is equal to psia – 14.7 at sea level. Psia is absolute pressure, which means it is gauge pressure + 14.7 psi. Now that I have indicated that, it relieves a lot of pressure... Below the calculator is an approximate chart relationship of temperature to pressure. Be aware that various brands and conditons will cause variations.