What is expansion valve? This is a piece of equipment that helps in reducing or increasing the pressure in a system. One of the most common types of the expansion valves is the thermal expansion valve or otherwise called TMV. This type of valve is commonly used in ventilation, heating or air conditioning or HVAC systems. In air conditioning system, there are two types of expansion valves which are the thermostatic valve and the capillary tubes.
There are two most common types of expansion valve, the capillary tube and the thermostatic expansion valve. The first one is usually used in a small sized unit while the other one is generally used in larger sized units. Usually the capillary tube expansion device is not actually a valve but a simple tube with similar material which is usually used in the air conditioner tubing. Here, there is no actually device to control the flow but it has its tube’s internal diameter, spiral shape as well as length which create restrictions that allows refrigerant into the expansion zone.
Usually, the most common failure of an expansion valve is due to the charge leak. As a result, the system contaminant lodge in the valve inlet portion of the system may affect the metering as well as the flow capability of the valve. The metering inconsistencies may have distinct characteristics. For instance, a starving expansion valve may result to frost forming on the inlet of the evaporator while flooded expansion valve has a hissing sound on the valve whenever the equipment or the system is shutting down.
The thermostatic expansion valve helps control the flow of the refrigerant at the same time functions at a varying temperatures and pressure points. On the other hand, the capillary tube is in the essence not really an expansion valve because it is just a simply tube but work as an expansion valve because it function the same like any other expansion valve. It is responsible in transmitting the pressure level in the system going to the sensing tube attached in the thermostatic expansion valve that basically functions as a throttle.