In a properly operating flooded system, what is the superheat leaving the surge drum?

In a properly operating flooded system, the superheat leaving the surge drum is ideally 0°F. This is because, in a flooded system, the refrigerant is meant to remain in a saturated condition as it leaves the surge drum. The surge drum is designed to maintain a sufficient liquid level that allows the refrigerant to flow into the compressor without vaporizing, ensuring that only liquid reaches the compressor inlet.

When the system is working correctly, there is no superheat because the refrigerant is not experiencing an increase in temperature above the saturation temperature for the pressure at which it operates. In essence, a superheat of 0°F indicates that the refrigerant is completely saturated and has not begun to vaporize into a superheated state.

If the superheat were above 0°F, it would imply that the refrigerant is partially vaporized, which could lead to inefficiencies or potential damage if too much vapor enters the compressor. Thus, maintaining 0°F superheat signifies the flooded system is functioning as intended.