What is essential for the metering device to function properly during flooding?

The proper functioning of a metering device during flooding is critically dependent on liquid refrigerant pressure. When a metering device—such as a expansion valve or capillary tube—is operating, it must accurately regulate the flow of refrigerant into the evaporator. The primary role of the metering device is to reduce the pressure of the refrigerant in a controlled manner, allowing it to change from liquid to vapor phase as it absorbs heat in the evaporator.

During flooding conditions, where excess refrigerant liquid enters the evaporator, the pressure of the liquid refrigerant must be maintained at a certain level for the metering device to respond appropriately. If the liquid refrigerant pressure is insufficient, the metering device cannot control the refrigerant flow effectively, leading to inefficient cooling and potential damage to the system. Therefore, maintaining proper liquid refrigerant pressure is essential for the metering device to function optimally and ensure the refrigeration cycle operates correctly.