Which technician correctly states the function of the thermostatic expansion valve and fixed orifice tube?

The thermostatic expansion valve (TXV) and the fixed orifice tube are both critical components in a refrigeration or air conditioning system that regulate the flow of refrigerant into the evaporator.

The thermostatic expansion valve adjusts the flow of refrigerant based on the temperature of the evaporator coil. It senses the temperature at the evaporator outlet and modulates the flow of refrigerant accordingly, ensuring that the coil is filled to the optimal level for efficient heat absorption. By maintaining the proper superheat within the evaporator, the TXV helps prevent liquid refrigerant from returning to the compressor, which can cause damage.

In contrast, a fixed orifice tube does not adjust the flow of refrigerant; instead, it provides a consistent flow rate that does not change regardless of the conditions in the system. This means that the refrigerant flow is predetermined, and it relies on the pressure differential between the high-pressure and low-pressure sides of the system to function correctly.

Both statements made by technicians A and B reflect these functions accurately. Therefore, the correct response recognizes that both describe the roles of the thermostatic expansion valve and the fixed orifice tube correctly, thus affirming the completeness of their understanding of these components.