Detailed refrigerated air dryer leak troubleshooting guide – external and internal leakage

Writer： admin Time：2022-09-27 00:00:00 Browse：388℃

Refrigerated air dryer leak is a common problem. The most obvious appearance of refrigerant leakage in the refrigeration dryer is that the refrigerant pressure gauge is zero. Firstly we need to find the leaking. Then we can solve the problem. Besides, need to check whether it is an external leak or an internal leak. The latter is usually evaporator leakage. Detecting leaks requires patience, carefulness and certain methods.

How to judge whether the refrigerant air dryer is leaking internally or externally?

In fact, the most common is external leakage. We can confirm external leakage by simple methods. But identifying dryer internal is slightly more difficult.

(1) Visually identify dryer leaks

Check to see if there are any obvious leaks, or if there is any obvious oil. Firstly, open the enclosure of refrigerant air dryer. Then look inside the machine. When the refrigerant is running, there will be compressor lubricating oil in it. If there is a refrigerant leak, it will bring lubricating oil out. So take a closer look inside the refrigeration dryer. If there is oil stains, it is most likely the leak.

Secondly, check the capillary copper tube inside the dryer. That is, those thin copper pipes. Check for breaks. Finally, mark the suspected leak spots.

(2) Check for dryer leakage with soapy water

Afterwards, add a certain pressure of inert gas. Use it to identify leaks. If possible, it is best to use nitrogen to keep the pressure. Gaseous Freon will also work without nitrogen. But strictly forbidden using oxygen to maintain pressure for leak detection. There is an explosion hazard.

When maintaining the pressure, add gas slowly at the beginning. Observe the refrigerant gauge pressure of dryer while applying pressure. Temporarily stop when the pressure reaches about 0.2Mpa. Then carefully listen to the sound of air leakage inside the dryer. If there is, you can find the leak according to where the sound is. If not, continue to pressurize to 0.4~0.5Mpa. Afterwards, find a sponge and dip it in soapy water. Apply soapy water to the area you just suspected. Then check all the connecting pipes (copper nuts) inside the machine. Also apply the soapy water. If there is a leak, there will be air bubbles blowing out. This process needs to be very careful.

(3) Check if the refrigerated air dryer is leaking internally

The above two methods are for external leakage. Of course, you can also use a leak detector to test. If you still can’t find the leak, then it is very likely that the evaporator is leaking

Evaporator internal leakage is more troublesome to deal with. Firstly, it is necessary to confirm whether there is internal leakage. We can disconnect the evaporator and refrigeration system. Then maintain pressure alone. If you notice a drop in pressure, then it can make sure it’s internal leak.

There is another simple method. Firstly, discharge all the refrigerant in the refrigeration dryer. Zero the evaporation pressure gauge. Then look at the guage again. If the pressure comes back up after a few hours, it means there is air in the evaporator. That is, there is an internal leak in the evaporator.

How to repair the external leak of refrigerant air dryer?

Different leaks require different repair methods. For the loose points of the bell mouth, you only need to use a wrench to tighten. If it is leakage points of copper pipe welding type , it needs brazing. Brazing and repairing leaks is one of the most common repairing leaks methods in the refrigeration maintenance industry. What is brazing? It is to use oxygen and acetylene flame to heat the low silver electrode. And heat the required repair welding parts. Let the electrode and the leakage parts together. So that it can block the leak.

Before brazing, should vent pressure of the refrigeration system to zero. Then use the brazing gun. Firstly turn on the acetylene. Then add oxygen appropriately after lighting. Slowly adjust the ratio of oxygen and acetylene gas. Make the flame become a neutral flame. That is, an oxidizing flame. Finally heat the leakage parts and silver electrode. Dissolve them together.

After repairing the leak points, it needs to maintain pressure to the dryer system again. So as to confirm whether the leak welding is successful. In addition, the system needs to be evacuated. Then add refrigerant to the refrigerated air dryer.

How to solve the internal leakage of refrigeration air dryer?

Firstly, dissemble the evaporator part. Then cut evaporator casing tube. And take out the evaporator. We can cut it with acetylene or a grinding wheel. Afterwards, put it in water. Then pressurize with a compressor. If there are bubbles in the water, it means that evaporator is leaking.

At this time, we need to mark the leak points. Then solder the leaks. After you’re done, still need to put it in the water. Continue to maintain pressure. Make sure that there are no leaks. Of course, if you don’t know how to fix it, it’s best to ask the manufacturer to replace it. Finally we need put the evaporator back in the casing. Then weld the tube. Re-install the insulation. Afterwards, re-assemble it to the refrigerant air dryer. In the end, it still needs to maintain pressure to the whole dryer system. It’s to ensure there is no leakage.

Why does the refrigerated air dryer leak?

Likewise, we still analyze the reasons from two aspects. The causes of internal and external leaks are different.

(1) The reasons for external leakage of refrigeration dryer

① New machine leaks refrigerant. It’s most likely due to transportation. Bumpy or violent loading and unloading will cause damage to the welds of the refrigerant pipes. Or lead to capillary breakage. So it will lead to leakage.

② After using it for a month, find something like oil coming out of the bottom plate. It’s actually a refrigerant with lubricant. It may be that the welding process is not done well. Or it’s due to transportation before. But the leak is slight.

③ The refrigerant dryer leaks after a year or two. It is very likely that the copper pipe is leaking at the welding.

(2) The reasons for internal leak of refrigerated dryer

① Some refrigerant dryer factories use cheap materials. The thickness of evaporator copper tubes are very thin. It is easily damaged by corrosion after a period of use. In addition, some manufacturers don’t do stick pressure test. Therefore, the welding part of the copper tube is easy to leak. Evaporator leaks are generally located at the ends.

② Some manufacturers do not use hot gas bypass valve. Or use an bad quality hot gas bypass valve. Therefore, the superheat degree inside the evaporator is not stable. This will cause excess cooling capacity. This will result in frost and icing.

There is another situation. Some users use variable speed drive screw air compressors. But the refrigeration air dryer is fixed frequency. That is, the cooling capacity of the dryer is fixed. If the air compressor runs at low frequency for a long time, the cooling capacity of dryer will be far greater than the heat load of the compressed air. Therefore, the cooling capacity of refrigerated dryer will be excessive. Likewise, frost and ice can form inside the evaporator. Finally it may cause evaporator leaks after expansion.

③ If it is a water-cooled refrigerant dryer, the cooling water quality will also have an impact. If the water quality is not good, there will be impurities in it. Then the water volume regulating valve may be stuck. Therefore it will lose the regulating function. This results in too much or too little cooling capacity. When the cooling capacity is too large, it will freeze. Eventually it will freeze the evaporator. So it leads to internal leakage of refrigerated air dryer.

If it is an air-cooled refrigeration dryer, the filter dryer quality also plays a role. If the filter drier fails, impurities will block the throttling device. The supply of refrigerant to the evaporator is unstable. Ultimately, it will also affect the life of the evaporator.

④ It can be seen from the third point above that the water volume regulating valve and the throttling device have an impact on the life of the evaporator.

How to prevent the leakage of refrigerated air dryer?

① Firstly, we must choose a good refrigeration dryer manufacturer. Price is not unique. Quality is also critical. For example, ask whether the heat exchange system uses thick copper pipes. How is leak testing done? How about the quality of refrigeration accessories? Good raw materials and parts can effectively avoid leakage.

② Secondly, installing pre-filter front of refrigerant dryer is necessary. In this way, most impurities do not enter the dryer. Therefore, it is possible to avoid breaking the copper tube by hitting the evaporator.

③ Thirdly, provide timely human intervention. Further strengthen the patrol inspection of refrigerated dryer. Especially when the season changes, pay attention to observe whether the high and low pressure of the refrigerant are within the normal range. And adjust the refrigeration system according to the temperature changes in the four seasons. Avoid freezing due to excessive cooling capacity.

④ Develop a startup strategy for air compressor and dryer. According to the gas consumption of the factory, increase or decrease the number of air compressors and refrigeration dryers. Avoid long-term low-frequency operation of the air compressor. Thereby avoiding the mismatch between the heat load of the compressed air and the cooling capacity of dryer.

⑤ Strengthen the maintenance of refrigerant air dryer

Firstly, check the drain valve regularly. Make sure refrigeration dryer is draining properly. At the same time, replace the filter element in time. Prevent impurities from entering the evaporator. Also, regularly check the performance of various refrigeration accessories. If damaged, replace them in time. In addition, regularly check the cooling water quality. Change to clean soft water. Check and clean the cooling water filter. So keep it in a clean state. Good maintenance can effectively avoid the leakage of refrigerated air dryer.