R134A is a refrigerant --- a liquid capable of vaporising at low temperature --- used in automotive air conditioning and other applications. According to the U.S. Environmental Protection Agency, R134A is not flammable at ambient temperatures and not corrosive to metals such as aluminium, copper and stainless steel.
Pressure Temperature Chart
Like other refrigerants, the pressure of R134A corresponds to its temperature. You can determine the refrigerant pressure at any temperature between '22 and 202 degrees Fahrenheit by reading the value from a pressure temperature chart.
In a high-temperature refrigeration box, where temperatures typically range from 7.22 to 15.6 degrees Celsius, the coil temperature is, typically, between 10 and 20 degrees Fahrenheit colder than the box itself. This difference is simply known as the temperature difference.
Normal Running Pressure
For the normal running pressure in an R134A system, the coil should run at 9.98 Kilogram per square inch (psi) at the lowest temperature (45'20 = -3.89 degrees Celsius). Similarly, at the highest temperature (60'20 = 4.44 degrees Celsius), the coil should run at 57 psi. In other words, the normal running pressure of R134A is between 22 and 57 psi in such a system.