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Ningbo Jintian Copper (Group) Co., Ltd.
Ningbo Jintian Copper (Group) Co., Ltd.

Analysis of the Leakage of the Copper AC Tubing

The leakage of air-conditioning copper pipes is a fatal defect of air-conditioning refrigeration copper pipes. Once the leakage occurs, all the refrigerant will overflow from the refrigeration copper pipes, and the operation of the air-conditioning system will also stop due to the lack of transmission medium.


1. The reasons for the copper AC tubing's leakage come from two aspects:


① Manufacturing factors;


② User factors.


③ end customer factor


2. Reasons for the manufacture of the copper AC tubing


① Eddy current flaw detection missed inspection.


GB stipulates that copper tubes must be subjected to 100% eddy current flaw detection, and stipulates the diameter of artificial defects (through holes) on the sample tubes used for checking flaw detectors to ensure the sensitivity of eddy current flaw detection and prevent excessive defects from being missed.


This requirement can be fully guaranteed by regular large-scale aircon copper pipe suppliers, because the flaw detection is on-line. This on-line eddy current flaw detection ensures that all lengths of the tubes have undergone eddy current testing, which is 100% flaw detection.


Some copper pipe factories are not like this, or do not go through eddy current flaw detection, or use a low-standard eddy current flaw detector for random inspection. In this way, the copper pipes have defects that exceed the standard and are missed or undetected, resulting in leakage of the air conditioner when the user uses it.


② Eddy current inspection detects defects, but the copper tube surface is not marked or the marking is inaccurate and unclear.


In the production process of copper tubes, the defects detected by eddy current inspection require that ink marks be used to cover the defects that exceed the standard, so that the user can remove the defective copper tubes during use.


However, due to the insufficient adhesion of the ink selected by the manufacturer in the production process, improper adjustment of the inkjet spray gun, incomplete drying, and fading of the ink composition at high temperature, the user cannot detect the eddy current flaw detection during use. Once the defective air conditioner copper pipe is used in the air conditioner, it is bound to cause leakage.


3. Reasons for the use of copper AC tubing users


The user uses the copper tube to make the two-piece process: cutting-bending-expansion-cleaning-welding-pressure test.


① Misuse of defective tubes detected by eddy current inspection.


Under normal copper tube production conditions, copper tube eddy current inspection not only marks the number of wound spots on each coil, but also paints black marks on the wound spots, so that users can identify this "black tube" in use.


Air-conditioning and refrigeration enterprises should make it clear to operating workers, especially new workers, in order to prevent such injured pipes from being installed on air-conditioning and refrigeration units.


We have found this problem many times when we go deep into customer service. Some workers asked us what happened to the black on the pipe, while others were dissecting substandard products. It was precisely because the "black pipe" was installed on the product that caused the air conditioner Refrigeration unit leaking.


② Processing problems


In the process of forming the two devices, the main air conditioner has to go through such links as bending, expanding, flaring, and welding.


In the process of bending the pipe, the bending part is subject to local stress, resulting in local overstretching, resulting in cracks, dark cracks and other problems. Once filled with refrigerant, refrigerant leakage often occurs here.


After the air-conditioning copper tube passes through the fins, it needs to be expanded on the tube expander. The tube expander is divided into two types: vertical and horizontal. The tube expander mainly expands the two devices with longer length, and the efficiency is relatively low.


In the process of expanding the tube, because the core expanding is to increase the size of the copper tube by interfering with the inner diameter of the copper tube, the outer diameter of the copper tube is fully contacted with the aluminum foil heat sink. In the process of expanding the tube, it is easy to cause the head to scratch the copper tube, which will cause penetration damage and cause leakage of the copper tube.


③ Leakage caused by poor welding.


After the copper tube is pierced into the aluminum foil with holes, the tube should be connected with the tube, and it needs to be connected with a small elbow. In order to make the connection firm, in the production process, the small elbow and the copper tube are welded together with solder;


The welding method is divided into two types: manual and automatic. During welding, due to the quality of the solder, the flaring of the copper tube, and the presence of foreign objects on the welding surface, the welding is not solid, the formation of false welding, and the leakage of refrigerant.


4. Reasons for use by end customers


The end-customer's air-conditioning use environment is slightly harsh, resulting in copper pipes being exposed to high temperature, high humidity or acid environment for a long time, resulting in gradual corrosion of the surface of copper pipes. Known as "ant colony corrosion". The copper tube in the severely corroded state is lumpy or granular when extruded by external force.