Vacuum leak detection is the process of detecting the location and size of air leaks in a vacuum system.

Leakage, also known as actual leakage, is the phenomenon of gas flowing from the high-pressure side to the low-pressure side through holes or gaps in the system.

Virtual leakage is a physical phenomenon relative to real leakage. This phenomenon is caused by factors such as material release, desorption, re evaporation of condensed gases, permeation of gases through the reactor wall, and outflow of gases from dead spaces within the system, resulting in an increase in gas pressure in the vacuum system.

Airtightness is a characterization of the performance of vacuum system walls in preventing gas permeation, which includes leakage through holes (or gaps) and material permeation.

The minimum detectable leak rate refers to the minimum value of the leak rate that a certain leak detection method can detect.

**Sensitivity refers to the minimum leakage rate that a leak detection instrument or method can detect under * * conditions. For leak detection instruments, * * sensitivity is also known as instrument sensitivity.

Leak detection sensitivity refers to the minimum leakage rate that a certain leak detection method can detect under specific conditions. Leak detection sensitivity, also known as effective sensitivity.

Reaction time refers to the time from the implementation of the leak detection method (such as starting to spray leak gas) to the response of the indication method (such as instruments).

Elimination time refers to the time from when the leak detection method stops (such as stopping blowing and starting to extract leak gas) to when the indication of the indication method disappears.

Leakage rate refers to the amount of gas flowing through a leak hole (including gaps) per unit time.