Talking about the skills of vacuum leak detection?

Talking about the skills of vacuum leak detection?

Finding leaks quickly requires considerable experience and skill. Although there is no certain operating rules for vacuum leak detection, it is generally better to operate according to the following procedures and methods.

1) For the vacuum container or device in the process of manufacturing, it is best to use the bubble leak detection method.

Bubble leak detection is to fill the test piece with a certain pressure of leak-indicating gas and then put it into the liquid. The gas enters the surrounding liquid through the leak hole to form bubbles. The place where the bubble is formed is the location of the leak hole. The rate, the size of the bubbles, and the physical properties of the gas D liquid used can give a rough estimate of the leak rate.

When observed with the naked eye, there are generally three situations: the first is that the bubbles appearing are small, the formation rate is uniform, the bubbles last for a long time, and the leak rate ranges from about 10-5 to 10-2Pa·m3·S-1 ; The second case is the phenomenon of random mixing of large and small bubbles, and the leak rate ranges from about 10-2 to 10-1Pa·m3·S-1; the third case is that the bubbles are large, the formation rate is fast, and the duration is short. The leak rate range is about 10-1 to 1Pa·m3·S-1.

2) There seems to be no damage to the vacuum container or device in use, but when the pressure is found to rise sharply, first use a lit vacuum gauge and alcohol or acetone as a leaking liquid to check the places that are considered to be easily damaged.

(3) If the leak cannot be found despite the above-mentioned efforts, the hood (integration method) or the pressure rise method should be used to judge whether there is an air leak.

The so-called cover method is to cover the entire device with a vinyl plastic bag (cover), and then fill the bag with helium gas, that is, a method of immersing the entire vacuum container in helium for leak detection.

The so-called pressure rise method is a method of judging whether there is air leakage by closing the main valve, rough pumping valve and air leakage valve after fully pumping, and using the change of the pressure rise in the B-A ionization vacuum gauge to determine whether there is air leakage. This pressure rise variation is typically shown by the solid line in Figure 1.

It is the sum of the pressure rise caused by the air leak and the pressure rise caused by the material outgassing, and finally it is a linear rise proportional to time. When the curve shows the above state, it indicates that the device is leaking.

Because there is no leakage and only material outgassing, the curve should be saturated; when there is no material outgassing and only air leakage, it will be a straight line proportional to time at the beginning.

Once the operation is proficient, you can not only analyze the residual gas, but also roughly judge whether there is a leak (pay attention to the 02 peak and the Ar peak, if there is an 02 peak, it can be considered a gas leak at first; even if you cannot see the 02 peak, as long as the Ar peak is It is more than normal, and it can also be considered that the device is leaking). Inspection with the hood method can save time, so in order to determine whether there is an air leak, it is best to use the hood method.

If there is leakage in the device, and the leakage hole is not the limiting factor of the pressure in the device, then the vacuum degree can be further improved after baking without detecting the leakage.

4) Leak detection. To find the leaking place, it is nothing more than checking the possible leaking places one by one. Its precautions are listed as follows:

① When using helium, a gas lighter than the atmosphere, as the leaking gas, start from the top of the device (when checking from the bottom, due to the rise of helium and leaking from the top leak, it will be mistaken for a leak at the blowing place). With heavier gases such as butane, propane and alcohol (liquid), start from the bottom of the unit.

②If a leak is found, stick it with vinyl tape (a substance that cannot pass through the leaking gas), temporarily block the leak, so as not to mistake it for the leak in the next inspection, and then Keep checking.

③ If all inspections are completed, check again with the hood method to see if there are any leaks If a leak is found, it can be confirmed that there is no air leak). If it is judged that there is no air leakage, you can proceed to repair.

1) For the vacuum container or device in the process of manufacturing, it is best to use the bubble leak detection method.

Bubble leak detection is to fill the test piece with a certain pressure of leak-indicating gas and then put it into the liquid. The gas enters the surrounding liquid through the leak hole to form bubbles. The place where the bubble is formed is the location of the leak hole. The velocity, the size of the bubbles, and the physical properties of the gas D liquid used can give a rough estimate of the leak rate.

When observed with the naked eye, there are generally three situations: the first is that the bubbles appearing are small, the formation rate is uniform, the bubbles last for a long time, and the leak rate ranges from about 10-5 to 10-2Pa·m3·S-1 ;The second case is the phenomenon of random mixing of large and small bubbles, and the leak rate ranges from about 10-2 to 10-1Pa·m3·S-1; the third case is that the bubbles are large, the formation rate is fast, and the duration is short. The leak rate range is about 10-1 to 1Pa·m3·S-1.

2) There seems to be no damage to the vacuum container or device in use, but when the pressure is found to rise sharply, first use a lit vacuum gauge and alcohol or acetone as a leaking liquid to check the places that are considered to be easily damaged.

(3) If the leak cannot be found despite the above-mentioned efforts, the hood (integration method) or the pressure rise method should be used to judge whether there is an air leak.

The so-called cover method is to cover the entire device with a vinyl plastic bag (cover), and then fill the bag with helium gas, that is, a method of immersing the entire vacuum container in helium for leak detection.

The so-called pressure rise method is a method of judging whether there is air leakage by closing the main valve, rough pumping valve and air leakage valve after fully pumping, and using the change of the pressure rise in the B-A ionization vacuum gauge to determine whether there is air leakage. This pressure rise variation is typically shown by the solid line in Figure 1.

It is the sum of the pressure rise caused by the air leak and the pressure rise caused by the material outgassing, and finally it is a linear rise proportional to time. When the curve shows the above state, it indicates that the device is leaking.

Because there is no leakage and only material outgassing, the curve should be saturated; when there is no material outgassing and only air leakage, it will be a straight line proportional to time at the beginning.

Once the operation is proficient, you can not only analyze the residual gas, but also roughly judge whether there is a leak (pay attention to the 02 peak and the Ar peak, if there is an 02 peak, it can be considered a gas leak at first; even if you cannot see the 02 peak, as long as the Ar peak is It is more than normal, and it can also be considered that the device is leaking). Inspection with the hood method can save time, so in order to determine whether there is an air leak, it is best to use the hood method.

If there is leakage in the device, and the leakage hole is not the limiting factor of the pressure in the device, then the vacuum degree can be further improved after baking without detecting the leakage.

4) Leak detection. To find the leaking place, it is nothing more than checking the possible leaking places one by one. Its precautions are listed as follows:

① When using helium, a gas lighter than the atmosphere, as the leaking gas, start from the top of the device (when checking from the bottom, due to the rise of helium and leaking from the top leak, it will be mistaken for a leak at the blowing place). Heavier gases such as butane, propane, and alcohol (liquid), start from the bottom of the unit.

②If a leak is found, stick it with vinyl tape (a substance that cannot pass through the leaking gas), temporarily block the leak, so as not to mistake it for the leak in the next inspection, and then Keep checking.

③ If all inspections are completed, check again with the hood method to see if there are any leaks If a leak is found, it can be confirmed that there is no air leak). If it is judged that there is no air leakage, you can proceed to repair.

Thermal Evaporation Vacuum Coating Machine

System Summary

DankoVAC Evaporation Vacuum Plating Machinery is easy to operate with high performance, equipped with thermal evaporation system, to melt and vaporize the metal wire (like aluminum wire, brass wire) to deposit on the substrates, to get the metallic effect of decoration and beautified.

• Structure Type: Vertical structure with single or double doors or Horizontal structure with single door.

• Substrate Material: ABS, PS, PC, PP, PVC, Nylon, TPU (Plastic materials), acrylic glass.

• Coating Film: Aluminum, Chrome, Copper.

• Color: Silver, Gold, Semi-transparency, Red, Blue, Green, Grey, Black, Multicolor, purple and so on.

• Equipment with: UV line / manual spraying / soaking method.

• Consumables in production: Aluminum / Chromium / Brass Wires, Painting oil and color

APPLICATION:

• Disposable tableware, such as fork and spoon.

• Plastic Artworks, such as Christmas ball, plastic pearls.

• Clothing Accessories, such as buttons, zippers.

• Shoe Materials, such as heels, shoes flowers.

• Fittings, such as fan button, toys, phone shell, cosmetic bottles and caps.

• Glass jewelry, glass diamond, rhinestone.

• Car logo, Exterior & Interior Trim parts, car wheels.

• Other plastic products.