After letting the J-B Weld set over the weekend, the system was ready to be tested for the first time. Dr. Bulman had a chamber set up with a thermocouple pressure gauge, so we attached my chamber in series with his, with both chambers being connected to my Alcatel roughing pump. We also included a shutoff valve between the pump and the two chambers in order to test the chamber's ability to hold a vacuum once the pump had been shut off. A sketch of the system is shown below. The middle chamber is Dr. Bulman's (with the gauge) and the one on the right is mine:
When we turned the pump on for the first time, Dr. Bulman said it sounded fine so there weren't any large leaks. It made a constant gurgling sound and didn't sputter. We left the pump running for a few days, and the pressure went down to 60 microns or so, but then increased to 200 microns and stayed there. Anatol then closed off the valve (as seen in the top picture) and the system did not drop pressure immediately, which was a good sign. It took about a day for the pressure to rise close to standard atmospheric pressure.
The first test was a success! Not only did we manage to get the pressure down to a very low level, but when the pump was turned off, the chamber was able to hold the vacuum for a while. Also, when we disassembled the chamber later, the gasket was still in good condition.
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