When should a cap tube be considered for use in a refrigeration system?

Capillary tubes are typically utilized in low load systems due to their inherent characteristics. These tubes are essentially fixed orifice devices that allow refrigerant to flow from the high-pressure side to the low-pressure side of the system based on the pressure differential. In low load scenarios, where the cooling demands are less frequent or lighter, capillary tubes can effectively manage the refrigerant flow without the need for a complex control system.

Additionally, capillary tubes ideally suit systems that do not experience large fluctuations in cooling requirements. Their simple design makes them more cost-effective for low capacity units, such as small refrigerators and refrigeration units that need a steady, linear flow of refrigerant. In contrast, high capacity and variable load systems require more flexibility and control that capillary tubes cannot provide, often relying on expansion valves instead. Therefore, the choice to use a cap tube is particularly aligned with the needs of low load refrigeration systems.