Since the shaft seal needs to keep the LOX in, I used one of the McMaster PTFE spring energized seals. I found suggested gland dimensions in the Balseal catalog (close enough) but had to modify them a bit. The tube in the middle is nominally 1 inch OD but since it isn't perfectly round, I turned it down to 0.995. So, I just adjusted the seal gland dimensions by -0.005 for both the OD and ID. With a good chamfer on the tube, I was able to insert it without too much effort. I think this "rod wiper" kind of seal tends to expand and seal better under pressure doesn't it? The cup with the spring side points toward the liquid.
-Bob On 11/18/2013 01:45 PM, Ben Brockert wrote:
Ha, Rocket 1. I was giving the Copenhagen guys a hard time last week about un-creatively calling their huge new building "HAB 2". That's an impressive set of parts. Did you do anything special in analyzing the design of the shaft seal? I usually avoid that style of seal design because the operating pressure is trying to unseal it, but I haven't done the calc to see how the pressure compares to the preload. Ben On Sun, Nov 17, 2013 at 9:15 PM, Robert Watzlavick <rocket@xxxxxxxxxxxxxx> wrote:I completed hydro-testing today on a prototype tank based on the design I mentioned a few weeks ago. In summary, no leakage or damage was observed after 2 cycles to 750 psi. There looks to be a small amount of permanent deformation in the center of the bulkheads (~0.005 inches) but nothing to worry about. While assembling the parts, as the o-ring slid past the tank wall holes, it shredded some small pieces off. I didn't debur the inside hole edge as well as I could have so I'll clean them up a bit and see if it helps. Discussion is at: http://www.watzlavick.com/robert/rocket/ photos are at: http://www.watzlavick.com/robert/rocket/rocket1/photos/index.html -Bob
