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TOPIC: Improvements to Cell Design
#485
11 years 7 months ago
Improvements to Cell Design
In looking at the drawings of the cell design, several improvements come to mind, based on my previous experience in building similar cells that required the ability to withstand both vacuum and pressure at elevated temperatures.
The first recommendation is to use hermetic metal-ceramic seals for all the electrical feedthroughs. This type of feedthrough is widely available in the Conflat flange form factor. In the 1.33" size up to four isolated electrical connections are available. It is relatively easy to machine the ends of the cell to accept a 1.33" CF feedthrough. Just make sure the flange is thick enough that you can drill blind holes for the six mounting bolts. Use the Viton gaskets furnished with the 1.33" CF flanges. The cell I'm designing uses one CF feedthrough on each end.
The second recommendation is to use a radially loaded Viton O-ring against the glass tube rather than relying on an axial seal. A radial seal does require an inner groove be machined, but the advantage is that the O-ring seats against the side of the glass tube rather than the bottom.
Gas/vacuum can be connected by using a 1.33" through CF flange and brazing 1/4" SS tubing into the flange. The other end of the SS tubing can be terminated with a VCR vacuum fitting. VCR fittings use a compressed metal gasket and yield a robust seal at both vacuum and pressure.
Jeff
The first recommendation is to use hermetic metal-ceramic seals for all the electrical feedthroughs. This type of feedthrough is widely available in the Conflat flange form factor. In the 1.33" size up to four isolated electrical connections are available. It is relatively easy to machine the ends of the cell to accept a 1.33" CF feedthrough. Just make sure the flange is thick enough that you can drill blind holes for the six mounting bolts. Use the Viton gaskets furnished with the 1.33" CF flanges. The cell I'm designing uses one CF feedthrough on each end.
The second recommendation is to use a radially loaded Viton O-ring against the glass tube rather than relying on an axial seal. A radial seal does require an inner groove be machined, but the advantage is that the O-ring seats against the side of the glass tube rather than the bottom.
Gas/vacuum can be connected by using a 1.33" through CF flange and brazing 1/4" SS tubing into the flange. The other end of the SS tubing can be terminated with a VCR vacuum fitting. VCR fittings use a compressed metal gasket and yield a robust seal at both vacuum and pressure.
Jeff