The Plumbing

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1. 4” Gate Valve between Chamber and Diffusion Pump
2. Chamber Thermo Couple gauge (this pipe goes directly to chamber!)
3. 1.5” valve between chamber and rough pump
4. 4” diameter, 16” long, 4 stage diffusion pump (running on 3 out of 4 heaters, I thought the pump was 220v, whoops!
5. Diffusion Pump exhaust thermo couple gauge
6. 1.5” pneumatic valve between diffusion pump exhaust and rough pump
7. Rough pump vent plug (used during shutdown)
8. Vibration dampening pipe (First try went without, big noisy mistake!)

I acquired all these VERY important parts from an Ebay auction hosted by Pete from rec.craft.metalworking (Thanks Pete!) I don’t think Pete ever got a chance to use any of these items prior to selling them, but I can say whoever used it last, made the mistake of opening a HOT diffusion pump to atmospheric pressure, as ALL the plumbing was full of thick black burnt oil! I had to take every thing apart, un-solder all the joints, and clean them out with a rotary tool. I made the mistake of trying to Silver Solder the parts back together, and quickly realized my Oxy-Acetylene torch didn’t have a big enough tip! Instead of Silver solder I used plain old plumbing solder to put everything back together with. Seems to have worked out ok J

Only other interesting part to tell while were here is my choice of pump oils. The advice is to use incredibly expensive synthetic diffusion pump oils, that cost hundreds of dollars per quart! I couldn’t afford this option so I found a Hydro Carbon based oil (Invoil 20) to use instead. Fortunately this stuff was ONLY $65 per gallon! Appears to work VERY well for this application, and a bonus is I can use the same oil in both the Diffusion Pump as well as the Rotary Roughing / backing pump!