Vacuum Pump Seal Carriers for High-Temperature Chemical Resistance
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Solution Overview
Problem
Vacuum pumps in high-temperature applications, such as semiconductor and solar panel manufacturing, face challenges with sealing materials that have short lifetimes and are sensitive to chemical exposure, leading to ineffective sealing and frequent replacements.
Innovation Solution
A seal system comprising a toroidal seal element positioned between inner and outer seal carriers, with retention means and a gas supply system to enhance chemical resistance and temperature resistance, using materials like silicone-based polymers and metallic or ceramic components to extend seal life and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If FFKM-type elastomer seals are used to achieve acceptable temperature resistance up to 240°C, then temperature resistance is improved, but service life becomes too short (3-6 months) due to compromise from aggressive process etch or cleaning gasses
Solution Approach 1:
The seal system is divided into two distinct components: a seal element made of chemically resistant material (such as PTFE or PCTFE) and a seal carrier made of temperature-resistant material (such as FFKM elastomer or metal). This segmentation allows each component to specialize in one function - the seal element provides chemical resistance while the seal carrier provides temperature resistance and structural support, thereby resolving the contradiction between temperature resistance and service life.
Solution Approach 2:
The seal system uses a composite structure combining different materials with complementary properties. The seal element uses fluoropolymer materials (PTFE, PCTFE) for chemical inertness, while the seal carrier uses FFKM elastomer or metal for high-temperature stability. This composite approach allows the system to achieve both long service life through chemical resistance and acceptable temperature resistance, eliminating the need to choose between the two properties.
2Temperature
If metal seals are used to achieve high temperature resistance, then temperature resistance is improved, but clamping forces required are very high and gradual tightening methods must be employed
Solution Approach 1:
The seal system applies local quality by using different materials in different locations for different functions. The seal element made of flexible fluoropolymer material is positioned where sealing contact is needed, providing both chemical resistance and flexibility. The seal carrier made of rigid material provides structural support and distributes clamping forces. This local differentiation allows the system to achieve high-temperature resistance without requiring excessively high clamping forces, as the flexible seal element compensates for minor misalignments and distributes the load.
3Ease of manufacture
If FKM-type elastomers are used as sealing materials, then ease of manufacture is improved, but lifetime becomes unacceptable at higher temperatures
Solution Approach 1:
The seal system segments the sealing function into two parts: a seal element made of chemically and thermally resistant fluoropolymer material (PTFE or PCTFE) and a seal carrier made of temperature-resistant material. This segmentation allows the seal element to provide long service life in aggressive chemical environments at high temperatures, while the seal carrier provides structural support. The modular design also simplifies manufacturing and replacement, as the seal element can be independently replaced without replacing the entire sealing assembly.
Data Source
AI summary
A seal for use in a vacuum pump comprises a seal element positioned between inner and outer seal carriers located at the inner and outer surfaces of the seal element. Each of the seal element and carriers is substantially toroidal in shape. The outer carrier comprises retention means to hold the seal element in position. The inner carrier comprises at least one recess located in a surface adjacent to the seal element, and the seal element comprises at least one protrusion on an inner surface, which extends into the at least one recess of the inner carrier. A seal system comprises the described seal and first and second flanges. Methods for enhancing the chemical resistance of a seal system for use in a vacuum pump, and the use of the seal or seal system to connect pipework, are also provided.