A new controllable capillary-type standard leak for vacuum applications

A standard leak is a device that, under prescribed conditions, emits the flow of a specified gas through a leak element at a controlled leak rate. This standard leak measures leaks quantitatively, a specification criterion in sealed vessels. The standard leak currently used in the industry is expensive, and there are limitations in developing the desired leak quantitatively. In this study, we tried to develop a standard leak that can be made inexpensively and easily calculable. A standard leak artifact was fabricated using a commercial capillary tube with micro-scale diameters made of fused silica. The developed standard leak was produced in various lengths and diameters, and their leak rate values were measured using the pressure rise method. Leak rates to 10 –10 Pa m 3 s −1 were observed with a relative expanded uncertainty of 22%. The results of this experiment showed that the material used was suitable for a standard leak, and it was possible to produce various standard leaks by controlling the geometry of the leak element.