What is the PSI of non-condensables in a system with a liquid drain temperature of 80°F and high side pressure of 138 PSIG?

To determine the PSI of non-condensables in a system with a liquid drain temperature of 80°F and a high side pressure of 138 PSIG, it's important to understand the relationship between temperature, pressure, and the presence of non-condensable gases in a refrigeration system.

In a properly functioning refrigeration system, the presence of non-condensables can elevate the pressure in the system. However, if you are considering non-condensables specifically at a certain point, and the liquid drain temperature is at 80°F, the corresponding saturation pressure for refrigerants typically used in these systems can be compared against the high-side pressure.

Since the high side pressure is given as 138 PSIG, this is approximately 154 PSIA when you account for atmospheric pressure (adding 14.7 PSI). The saturation pressure at 80°F for most common refrigerants is significantly lower than 154 PSIA. Under normal conditions, non-condensables should contribute to a pressure reading; however, in this scenario, it suggests that there may be an absence of substantial non-condensables affecting the overall pressure reading.

The correct answer indicates that the direct influence of non-condensables has led to an inferred value of 0 PSI in terms of their