How many principal parts does a TXV power element include, counting the charge?

The correct answer indicates that a thermal expansion valve (TXV) power element consists three principal parts, including the charge.

Understanding the function of a TXV is crucial for proper operation in refrigeration and air conditioning systems. The power element plays a pivotal role in controlling the flow of refrigerant into the evaporator based on the temperature of the refrigerant that leaves the evaporator.

The three principal parts of a TXV power element are as follows:

1. Sensing Bulb: This is located at the evaporator outlet and is filled with a refrigerant charge. It senses the temperature of the refrigerant vapor.

2. Capillary Tube: This connects the sensing bulb to the power element diaphragm. It allows the pressure changes in the bulb to affect the diaphragm, which in turn controls the valve opening.

3. Diaphragm: The diaphragm responds to the pressure generated by the refrigerant in the sensing bulb. It moves to modulate the valve opening, thereby controlling the flow of refrigerant based on evaporator load and preventing flooding or starvation of the evaporator.

Each of these components is integral to the operation of the TXV. The charge contained within the sensing bulb is critical because it helps