How to Install The Thermal Expansion Valve(TXV) in the correct way? The Thermal Expansion Valve (TXV) is an important piece of equipment in the water chiller system industry.

The expansion valve can only achieve the design effect and maximize the efficiency of the evaporator if it is installed correctly. The Thermal Expansion Valve function is the control the flow of coolant into the evaporator in response to the cooling load. In order to try and maintain a constant superheat. There are three parts of the expansion valve (only two parts for internally balanced type) that need to be installed in the system piping.

The thermal expansion valve should be installed close to the evaporator. The valve body should be placed vertically, not tilted, and should not be installed upside down. The valve repeats constantly and stabilizes the valve to ensure the correct amount of refrigerant can flow. Since the thermal expansion valve works according to the temperature felt by the sensing bulb, so the temperature sensing package. The installation is very important.

Thermal Expansion Valve



I. Valve body.

Because the expansion valve is the part that controls the refrigerant flow and pressure into the evaporator, so the closer it is to the evaporator, the smaller the pressure loss to the evaporator the better, so that the refrigerant liquid through the expansion valve enters the evaporator the more, to avoid the loss of cold as much as possible.

If you need to connect the distributor after the expansion valve, then if possible directly welded to the expansion valve outlet, if not directly connected, the distance between the two is best not to exceed 24in (610mm), otherwise, it will affect the distribution effect.

Valve body



Pay More Attention:

(1) For the temperature packets are gas-filled expansion valves, the valve body should be kept higher than the temperature of the temperature-sensitive package to avoid condensation of gas in the valve body, thus affecting the normal operation of the expansion valve.

(2) For the evaporative expansion valve before the refrigerant liquid pipeline has a rising pipeline and cause pressure loss, we should pay attention to this part of the pressure loss caused by the decline of the liquid saturation pressure, so that the subcooling degree becomes smaller, if the subcooling degree drops to 0, then the refrigerant liquid will appear flash gas, and finally affect the refrigeration performance.

(03) For the expansion valve with welded connection, pay attention to the operation specification, such as using a wet towel to cool down, so as not to damage the diaphragm and spring by high temperature.


II. The Sensing Bulb

Temperature-sensitive package because it is through sensing the evaporator outlet superheat degree to control the refrigerant flow into the evaporator, so it should be installed as close as possible to the evaporator outlet, if there is no suitable position, then the evaporator to the sensing bulb should be well insulated to avoid the temperature of the pipeline rising too much, which will affect the normal working condition of the temperature-sensing package.


Sensing Bulb



In the evaporator outlet pipe to designing a section of horizontal pipe to install the temperature-sensing package, because if the outlet pipe immediately rises, then the temperature-sensing package will not have a suitable installation position.

In the export pipe to set a storage oil bend or called storage liquid bend, mainly for the export pipe behind the rising pipeline here can accumulate refrigeration oil or unevaporated refrigerant liquid, when to a certain extent, will block the pipeline to make its pressure rise, so as to promote these oil or liquid rise, if not, accumulation in the horizontal pipe may affect the working state of the temperature-sensing package.


Sensing Bulb-1


If there is really no horizontal piping to install, then when you have to install in the vertical piping, it is better to be in the descending vertical piping.


After selecting the device of the temperature-sensitive package, it is a fixed temperature-sensitive package, for the evaporator outlet tube size, the fixed position of the temperature-sensitive package is shown in the following figure.

position of the temperature-sensitive packageposition of the temperature-sensitive package-1



If in a 2-1/8″ OD or larger line, there is.

(1) Subcooling is relatively small or requires more precise control.

(2) When the influence of external temperature on the temperature-sensitive package is relatively large.

It is possible to install the temperature sensing package on a sleeve and put this sleeve inside the line. It is absolutely not allowed to install the temperature sensing package at the bottom of the line, because there is usually refrigerant oil or refrigerant liquid at the bottom of the line, which will affect the temperature of the refrigerant gas sensing rice.

fix sensing bulb

fix sensing bulb right way



III. External balance tube

The external balance tube should be installed in the position immediately after the temperature-sensing package, not in front of the package, because it will disturb the refrigerant gas and thus affect the actual refrigerant gas in the location of the package. Other requirements can refer to the installation position of the temperature-sensing package.

external balance tube


Here is the article inform you what is the Differences between a thermostatic expansion valve and an electronic expansion valve



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