What must be used to determine proper Freon container gauge pressures?

• A. A standard pressure gauge at room temperature
• B. A chart based on ambient temperature
• C. A digital readout without temperature reference
• D. Manual inspection only

Answer: (B)

When working with Freon in a container, you interpret the gauge pressure using a chart that links ambient temperature to the cylinder pressure for the specific refrigerant. The pressure inside a charged cylinder depends on temperature because the refrigerant exists as a liquid–vapor mix whose vapor pressure rises or falls with temperature. Therefore, a single gauge reading isn’t enough—you need the ambient-temperature chart for that refrigerant to know what the pressure should be for a proper charge.

A standard pressure gauge at room temperature can be misleading if the cylinder isn’t at that temperature. A digital readout without any temperature context also lacks the necessary information to judge whether the charge is correct. The chart provides the necessary context by translating the current ambient temperature into the expected gauge pressure for the refrigerant, ensuring you assess or adjust the charge correctly.