Introduction to the basic knowledge of helium mass spectrometry leak detection

1.What is a vacuum leak detection

Vacuum leak detection technology is to use the appropriate method to determine whether the vacuum system, container or device leakage, to determine the position of the leak hole and the size of the leak rate of a technology, the corresponding instrument is called the leak detector. In the process of manufacturing vacuum systems, containers and devices, the vacuum leak detection technology is used to determine their vacuum air tightness and probe the position of leakage holes, so that measures can be taken to close the leakage holes so that the vacuum state in the system, containers and devices can be maintained.

The size of the leakage rate can be determined only after calibration. Generally using the comparison method, the leak rate of the detected leak hole can be obtained by comparing the leak hole with the standard leak hole on the leak detector. Method for detecting leaks in vacuum systems or their components. After a certain container is pumped for a long enough time, the pressure of the container does not change, and the amount of air pumped must be equal to the sum of the leakage and discharge of the container, that is, puSe=qL+q0, where pu is the limit pressure of the container, Se is the effective pumping rate at the exhaust port of the container, qL and q0 are the leakage and discharge of the container respectively. If the amount of exhaust is negligible, the equilibrium becomes puSe=qL, or pu=qL/Se. This shows that the ultimate pressure of the vessel is determined by the ratio of the leakage to the effective extraction rate. If the pumping rate is fixed (constant), the leakage should be reduced to obtain a low limit pressure, and the leak detection is the key measure.

Leaky holes are the holes and pores of vacuum containers. The pressure difference between the inside and outside of the container causes the gas to pass through the leak from one side of the container to the atmospheric side. The leak hole is generally very small, and the specific size of the leak hole can not be measured, so the size of the leak hole is expressed by the leak rate (the flow rate of gas through the leak hole under specified conditions). There is a pressure difference between the two sides of the leak hole, and the effect caused by gas flow can be used to detect the leak. In order to facilitate leak detection and easy to detect the location of the leak hole, the area of the detection is generally reduced as much as possible, so the first focus is on the leak detection of the parts. Parts are strictly leak-checked to avoid air leakage after assembly.

2.What is empty tank helium leak detection

Vacuum tank helium leak detection. According to the basic leak detection principle of helium leak detection, helium is used as a tracer gas to fill helium into the workpiece in the vacuum chamber, and then the helium leak detection instrument can judge the leakage of the workpiece with high precision, rapid and accurate.

3.The basic function of vacuum tank helium leak detection

The operator puts the workpiece in the vacuum box and connects the workpiece interface with the quick connector in the vacuum box. After the vacuum box door is closed, the system can complete the whole process of large leak detection, workpiece strength detection, evacuation, helium filling, leak detection and recovery automatically. The production beat is fast and the leak detection accuracy is high.

Process flow

A1: Install the workpiece ----- close the vacuum box door ----- vacuum the empty box, and fill the workpiece with high-pressure nitrogen ----- large leakage and strength detection;

B1: If A1 fails to pass the detection, the system will give an alarm, and the serial number of the workpiece with large leakage is shown as -----.

Nitrogen B2: if A1 test through, put the workpiece vacuum -- -- -- -- -- - -- -- -- -- -- - vacuum box of helium background -- -- -- -- -- the workpiece zero suppression in filling the helium -- -- -- -- -- -- -- vacuum mode, micro leak detection;

C1: If B2 fails to pass the detection, the system will alarm ----- cyclic inspection, the serial number of small missing workpiece is displayed ------ the detection program is suspended;

C2: If B2 passes the detection, the vacuum chamber is filled with atmosphere, and helium is recovered in the workpiece ------- the empty chamber is opened, and the detection is completed.

4.Characteristics and advantages of vacuum tank helium leak detection system

1.high pressure nitrogen strength detection in a vacuum box, to protect the safety of the operator

2.The helium background in the vacuum box is suppressed to zero, ensuring the accuracy and high precision of leak detection.

3.The automatic calibration function and automatic calibration program of the leak detector can calibrate the sensitivity and accuracy of the leak detector at any time.

4.the specially designed detection program to determine the specific leakage of the workpiece, and through the light and LCD operating screen display.

5. patented technology sealed joint, reduce misjudgment.

6.the electrical control system of the chain protection and sound and light alarm function, to ensure the safe operation of the system and reliable operation.

7.PLC control makes the system run clearly and realizes real-time monitoring and control.