Final answer:
A storage cylinder with R-500 refrigerant at 75°F is expected to be pressurized to approximately 120 psig, as determined by pressure-temperature charts for this specific refrigerant.
Step-by-step explanation:
The question pertains to the pressure of a storage cylinder containing R-500 refrigerant at room temperature, which is around 75°F. This refrigerant, like many gases stored under pressure, follows the gas laws, which help to predict how changes in temperature, volume, and pressure affect the gas. In the case of the R-500 refrigerant, appropriate reference materials like pressure-temperature (P-T) charts or manufacturer's tables are used to determine its pressure at a given temperature if no non-condensables are present.
According to typical P-T charts for R-500, the expected pressure of this refrigerant at 75°F (~24°C) without the presence of non-condensables would be approximately 120 psig. Psig means "pounds per square inch gauge" and indicates that the pressure is measured relative to atmospheric pressure, as opposed to "psia", which includes the atmospheric pressure in its measurement.