In order to understand the principles of leak detection methods, it is necessary to be familiar with the terminology used in the process. Leakage itself is defined as the passage through which gas or fluid escapes, and leakage refers to the escape of fluid. The leakage rate is the amount of fluid or gas that passes through the leakage within a unit time under a specific set of conditions. The minimum detectable leak is the smallest channel or defect that can be detected in a leak system, while the minimum detectable leak rate is the lowest leak rate that can be identified and measured. The minimum detection level is used to determine the sensitivity of the leak detector, but these values are often influenced by variables such as operating pressure and temperature There are usually two types of leaks in industrial environments. A 'true leak' is a local source of outflow, such as a simple hole that provides a direct channel for material to flow out. Real leaks may occur in the form of cracks, pipes, or defective openings. These types of leaks typically expand over time and may change due to fluctuations in temperature and pressure. Distributed leakage is a specific type of real leakage that involves fluid infiltration into an extended barrier, involving the diffusion of fluid particles in porous solids. Virtual leakage "is the second basic type of industrial leakage, which occurs due to the gradual desorption of gas from the surface or the escape of gas from sealed containers in vacuum systems. Vacuum systems sometimes experience both real and virtual leaks simultaneously

Choose a leak detection method

For a given application, there are several factors that may affect the effectiveness of the leak detector.

Large leakage: If the leakage is too large, the leak detector will malfunction, so the instrument and detection method should have a suitable working range for the problem. When the detector moves to full scale and cannot be reset unless it is removed from the leak, it may have been submerged by too many leaks Small leakage: A small leakage may not be recorded on the testing equipment because it is below the operating range of the instrument, making it difficult to detect and repair. If a detector records zero leakage, it does not necessarily mean that there is no leakage, as the reading may be inaccurate due to the size of the leakage. The parameters of the detection device should be determined based on the minimum detectable leakage and maximum leakage rate Characteristics of the system and tracer fluid: If gas or liquid tracer fluid is used to track the movement of materials, the tracer must not react with the components of the system, so as not to affect the operational performance. Gases with small molecular sizes and high diffusion rates, such as helium, are often effective in these situations Leakage location: If the purpose of the detection device is to locate and identify the leak, a probe or portable detector may be required to scan the surface of the fluid channel. In a vacuum system, tracer fluid can effectively detect the location of leaks, while in a pressure system, bubble detectors, liquid permeameters, and chemical indicators can play a better role