To achieve the 300 psig reading for a half-full R-410A cylinder at 90°F, which condition must be present?

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Multiple Choice

To achieve the 300 psig reading for a half-full R-410A cylinder at 90°F, which condition must be present?

Pressure in a cylinder containing refrigerant in equilibrium with liquid depends on the refrigerant’s saturated vapor pressure at the cylinder’s temperature, provided there are no non-condensable gases in the headspace. At 90°F, the saturated vapor pressure of R-410A is about 300 psig. If non-condensables (like air) are present, they add gas that doesn’t condense, pushing the total pressure higher than the pure refrigerant’s vapor pressure. So a half-full cylinder at 90°F will read around 300 psig only when non-condensables are absent. The other conditions don’t produce that exact reading: a temperature well below freezing would lower the pressure, and an empty cylinder would show a much lower pressure. Thus, absence of non-condensables is the condition that yields the 300 psig reading.

Pressure in a cylinder containing refrigerant in equilibrium with liquid depends on the refrigerant’s saturated vapor pressure at the cylinder’s temperature, provided there are no non-condensable gases in the headspace. At 90°F, the saturated vapor pressure of R-410A is about 300 psig. If non-condensables (like air) are present, they add gas that doesn’t condense, pushing the total pressure higher than the pure refrigerant’s vapor pressure. So a half-full cylinder at 90°F will read around 300 psig only when non-condensables are absent. The other conditions don’t produce that exact reading: a temperature well below freezing would lower the pressure, and an empty cylinder would show a much lower pressure. Thus, absence of non-condensables is the condition that yields the 300 psig reading.

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