Very low pressure gaz. Installation sizing

The correct design of a Vacuum installation requires a good understanding of the need to be met, as well as the constraints to be taken into account. The requirement may be a low pressure to be reached in a volume in a given maximum time. This type of requirement is referred to as "low pressure". volume pumping". We may also wish to maintain a low pressure in an enclosure despite the presence of a given gas flow. This is known as flow pumping". The values of these pressure, volume and flow parameters are generally known, since they are the technical specifications for a plant. On the other hand, the constraints to be taken into account are often not well known, and this is one of the difficulties in designing a plant. In such cases, assumptions have to be made, the relevance of which is a prerequisite for the accuracy of the design. These may include the desorption rate of materials, the internal conductance of components whose value is unknown, or the need to use existing components that turn out to be undersized. In the case of poorly known or prohibitive constraints, knowledge of plant sizing methods enables us to formulate recommendations, limit uncertainties, recommend measures or conclude that it is technically impossible. This article presents and implements all the parameters and constraints that need to be taken into account when calculating a real installation. However, some installations are complex in structure and operation, or present unusual features. It is not always possible to break down these systems into simpler sub-systems. A traditional computational approach, as described in this article, is hardly possible in these extreme cases, and the solution must call on advanced numerical modeling resources that are beyond the scope of this study.