High Temperature Sepcon Holder Concept

For the upcoming tests I have planned for H2 purification, I need a fixture to hold the pnc-Si membranes (Sepcon format) that is compatible with operation up to 500 C.  No polymers are going to work. I describe the approach I’m working on below.  I heard that Karl is developing a holder similar to what was used for the EO pump work.  Perhaps my design could be adapted to help serve his purposes

My plan is to use thin silver foil as a gasket material and press the chips in a precision-machined stainless steel fixture based on a commercial tube fitting by Swagelok® called VCR® fittings.  These fittings use two glands that are compressed together (w/ a gasket in between to provide sealing) with two nuts as shown in Figure 1.

 Figure 1:  Illustration of Swagelok® VCR® fittings.

I will have specially machined glands that can house the Sepcon chip with the silver gaskets. as shown in Figure 2.  The glands will be machined to have flat sealing surfaces and a square profile on the ends to provide a “tube-and-socket” fit that prevents the glands from twisting relative to each other.  The advantage of this approach is that the glands are registered relative to one another by the square projection and socket geometry such that when the nuts are tightened, the glands won’t twist, thus avoiding damage to the Si chip or membrane.  The glands will be attached to tubing with Swagelok® compression fittings, and this whole fixture will be placed in a furnace to set the temperature of the experiment.

Figure 2:  Sketches of modified Swagelok® fittings to hold Sepcon sample between silver gaskets.