EXPANSION VALVE

• 1 Sensitive bulb
• 2 Passage
• 3 Spring
• 4 Shutter
• 5 Adjustment screw
• 6 Evaporator inlet
• 7 Evaporator outlet
• 8 To the compressor low pressure circuit
• 9 From the filter high pressure circuit

The thermostatic expansion valve is fitted on the evaporator inlet and outlet ducts has the task of regulating the flow and expasion (fall in pressure) of the R134a fluid before it enters the evaporator.

The valve adjustment screw is calibrated in production and should not be tampered with: this would involve a decrease in the efficiency of the system.

The functions of this sophisticated meter which regulates the flow of refrigerant are as follows:

To meter the flow rate according to the load;

To analyze the evaporation temperature;

To stabilize the evaporation pressure;

To control the overheating of the refrigerant fluid.

The automatic regulation of the passage section for the refrigerant fluid inside the expansion valve is carried out by a sensitive bulb which is affected by the temperature of the coolant. According to the latter, it regulates the size of the opening

acting on a spring which moves the shutter and determines the extent of the expansion.

The increase in temperature at the evaporator outlet, measured by the bulb, causes the opening of the valve with a consequent increase in the flow rate of the fluid to the evaporator.

Conversely, at low temperatures, the flow rate is decreased.