Gas detection technology has a wide range of applications, in which a typical gas leak detection system is used to detect the tightness of the workpiece to be inspected. The external structure of the existing gas leak detection system includes several main components, such as an organic frame, a tracer gas source, a tracer gas inflation valve, a pressure sensor, a detection chamber, a leak detection valve, a return valve and a gas leak detector. One of the detection methods is the gas hood type gas leak detection system. The gas hood type gas leak detection system uses halogen gas, hydrogen or helium as the tracer gas, fills the tracer gas into the detection chamber (i.e. the gas hood), and uses the gas leak detector to detect the concentration of the tracer gas in the workpiece to be inspected. If the tracer gas index is detected to exceed the set value of the gas leak detector, it indicates that the workpiece to be inspected has leakage. The working principle and structure of the above gas hood type gas leak detection system include a tracer gas source, a tracer gas inflation valve, a detection chamber (i.e. a gas hood), a workpiece connecting pipe, a leak detection valve, a return valve, and a gas leak detector. The backflow valve is connected with the gas leak detector, and the detection chamber is connected with the tracer gas source through the connecting pipe. After the door of the detection chamber is closed, the tracer gas inflation valve is opened, and the tracer gas is charged into the detection chamber. When the pressure sensor detects that the inflation pressure of the detection chamber reaches a certain value, the tracer gas inflation valve is closed. Open the leak detector and return valve. If the workpiece to be inspected leaks, the gas in the detection chamber (i.e. the gas hood) will overflow from the workpiece leak hole into the workpiece to be inspected under the effect of differential pressure. The gas leak detector samples from the internal space of the workpiece to be inspected, and judges whether the workpiece leakage exceeds the standard according to the size of the tracer gas signal obtained. The main features of the gas hood type leak detection system are high leak detection accuracy, fast production rhythm and simple operation. The sampling space of the gas hood type gas leak detection system is the internal space of the workpiece to be inspected, the workpiece connecting pipe and the relevant pipe space connected with the gas leak detector. Before the tracer gas is filled, the gas in the clean sampling space is the reference background of the gas hood type gas leak detection system, and the tracer gas signal remaining in the sampling space after detection is called background noise. The tracer gas in the background noise may leak into the sampling space from the gas leak detection system itself, or it is the residual accumulation of the previous detection. The background noise of the tracer gas will increase with the repeated operation of the system. When the background noise exceeds a certain level, it will lead to the failure of the leak detector to operate normally, and even lead to false judgment of the detection results. The existing technology cannot effectively eliminate the residual accumulation of tracer gas, and it is usually necessary to eliminate the impact of background noise through repeated empty machine operation. The equipment operation efficiency is low, resulting in energy waste.

Gas concentration (including gas leak detection) detection technology has a wide range of applications, among which vacuum chamber type gas leak detection technology is a common technology, which detects the gas tightness of products through the detection of trace gas concentration.   The vacuum chamber type gas leak detection technology generally uses halogen gas, hydrogen or helium as the tracer gas. The  includes the detection chamber, vacuum pumping valve, vacuum pump, gas sensor valve, gas sensor, tracer gas valve and tracer gas source. During detection, first open the vacuum pumping valve, use the vacuum pump to pump the detection chamber to a high vacuum, and then open the tracer gas valve and tracer gas source, Fill the tracer gas into the workpiece to be inspected, finally open the gas sensor valve, and use the gas sensor to detect the concentration of the tracer gas outside the workpiece to be inspected. If the detected tracer gas signal exceeds the set value of the gas sensor, the workpiece to be inspected on the surface has leakage.   The characteristic of vacuum chamber type gas detection technology is that the workpiece is placed in the detection chamber. Before the workpiece is filled with tracer gas for leak detection, the vacuum pumping valve is opened first, and the detection chamber is pumped to a high vacuum with a vacuum pump. The requirements for vacuum degree are very high, otherwise the detection accuracy is easily affected. Because of the high vacuum, the tracer gas diffusion speed is fast, and the gas sensor can quickly detect the concentration of the tracer gas by the diffusion movement of the tracer gas in the vacuum environment without auxiliary inspiration. The vacuum chamber type gas leak detection system has high detection accuracy, fast production rhythm, and can realize full automatic detection without manual intervention. However, the equipment structure is very complex and strict, and the equipment manufacturing cost is high. Because of the need for a high vacuum, the vacuum system design is complex, and the manufacturing cost is also high, the promotion and use of the vacuum chamber type leak detection technology is limited by the high cost of equipment investment. At the same time, this technology cannot locate the leak point of the workpiece to be inspected.