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What Is A Expansion Valve In The Refrigeration System?
Feb 26, 2018

Cooling System

Expansion valve in the refrigeration system is one of the four components of the refrigeration system [compressor, condenser, throttle (expansion valve), evaporator].

Throttle valve also known as expansion valve or regulating valve.


1, the expansion valve adopts advanced structure of the dual-flow balance outlet.

2, expansion valve due to the use of dual-flow thermal expansion valve, the refrigeration system to save the number of expansion valves, check valves and solenoid valves.

3, expansion valve bi-directional balanced flow outlet, the static superheat degree with the condensing pressure or pressure changes through the valve port changes.

4, expansion valve has a stable degree of superheat, the system is stable.

5, expansion valve for refrigeration, air conditioning and other work needs.

6, expansion valve evaporation temperature range: -40 ℃ to +10 ℃.

7, expansion valve for R12 (Freon), R22 (difluorochloromethane), R134a and other media.


From the balance of view, the expansion valve can be divided into two types of internal and external balance.

Internal equilibrium pressure balance is taken at the inlet of the evaporator, and external equilibrium pressure is taken at the outlet of the evaporator. Internal balance expansion valve is generally used in home air conditioners. Automotive air conditioning is generally relatively large amount of cold, refrigerant pressure loss in the evaporator is also larger, so only the external balance.

From the superheating of the regulatory structure, the expansion valve is divided into internal and external modulation type.

Internal adjustment can only be adjusted before the installation of air conditioning system, which has the advantage of smaller size, compact structure, suitable for bulk styling products. Adjustable outside the air-conditioning system can be adjusted at any time according to the situation, with great flexibility, but the increase of parts makes the size and weight should be larger.


It mainly plays the role of reducing blood pressure and regulating flow.

At the same time it also has the function of preventing wet compression and liquid hammer to protect the compressor and abnormal overheating.