Correct Adjustment Method Of Expansion Valve In Refrigeration System

- May 01, 2018-

I. Before adjusting the thermal expansion valve, it is necessary to confirm that the air conditioning refrigeration abnormality is caused by the deviation of the thermal expansion valve from the best working point, and not because of the less freon, the blockage of the drying filter, the screen, the blower, the belt and other reasons.

At the same time, it is necessary to ensure the correctness of the sampling signal of the temperature sensor, the temperature installation position must be correct, absolutely can not be installed in the pipe directly below, in case the bottom of the pipe oil and other factors affecting the temperature of the correct temperature package.

    Two. Thermal expansion valve Adjustment considerations The adjustment work of the thermal expansion valve must be carried out under the normal operation condition of the refrigeration unit. As the evaporator surface can not be placed on the temperature meter, the suction pressure of the compressor as the evaporator saturation pressure, the table to obtain approximate evaporation temperature. The temperature of the return pipe is measured with the thermometer, and the heat is checked by comparing with the evaporation temperature. Adjustment, if the heat is too small, you can adjust the screw clockwise rotation (that is, increase the spring force, reduce the opening of the thermal expansion valve, so that the flow is reduced; Conversely, if you feel too much heat, that is insufficient supply, you can adjust the screw in the opposite direction (counterclockwise) rotation, so that the flow increased. Due to the thermal expansion valve temperature system in the actual work there is a certain heat inertia, the formation of signal transmission lag, the basic stability of the operation can be the next adjustment.   

    Therefore, the whole adjustment process must be patient and meticulous, adjust the rotation of the screw several times should not too fast.

    Three. Thermal expansion valve Specific adjustment steps 1. Downtime. Insert the probe of the digital thermometer into the insulating layer of the evaporator back inlet (corresponding to the temperature-sensing package position).

    Connect the pressure gauge with the tee of the compressor low pressure valve.

    2. Boot, let the compressor run 15 minutes above, into a stable operating state, so that the pressure indicator and temperature display to achieve a stable value.

    3. read out the temperature of the digital thermometer T1. The temperature corresponding to the pressure gauge is T2, and the heat is the difference between the two readings t1-t2. Note that both readings must be read at the same time. Thermal expansion valve overheating should be between 5-8 ℃, if not, the appropriate adjustment. The adjustment steps are: First remove the thermal expansion valve protective cover, and then rotate the screw 2-4. Loop, and other systems running stably, re reading, calculate the heat, whether in the normal range, not words, repeat the previous operation until the requirements, the adjustment process must be careful and careful.