If a 30-pound cylinder of reclaimed R-12 refrigerant has been stored overnight at 70°F, what should the pressure in the cylinder be approximately?

When dealing with refrigerants like R-12, it is essential to understand the relationship between temperature and pressure, as outlined in refrigerant pressure-temperature charts. For R-12 refrigerant, at a storage temperature of around 70°F, the corresponding pressure of the refrigerant in a cylinder can be determined.

At 70°F, the saturated vapor pressure of R-12 is approximately 70.2 Psig. This pressure reflects the equilibrium pressure of the vapor in the cylinder when the refrigerant is in a stable state at that temperature. Therefore, if the cylinder has stabilized overnight at this temperature, the pressure inside should closely match this expected value.

This understanding is crucial for technicians when handling refrigerants, as incorrect pressure readings may indicate issues like overcharging or improper storage conditions, which can compromise system performance or safety.