Pierce Nichols wrote: PN> Are those kinds of rotary seals an off the shelf item? Metal flexible PN> hose (essentially bellows restrained by a braid) seems to be a fairly PN> standard off the shelf item up to at least 2" diameter, and they're good PN> down to cryo temperatures.
One type of seals that can eventually fit the purpose, are PTFE seals with built in springs. They come in different forms and makes and can be used at LOX temperature. At SPL we have only some experience with these type of seals for static sealing. In our 25mm LOX line at the test stand we use them in the form of face seals. They are held in a grove like a O-ring and as they are C shaped and open to the pressure side, pressure will improve tightness. Some time ago in a discussion with Mark Blair over the Ausroc 2.5 project, he mentioned that in the States some types of the make Bal Seal can be bought from McMaster-Carr. The PTFE spring energized face saels we use at SPL are from the make Variseal. On the pages of Variseal and Balseal you should find a lot of useful information. Braided bellows with bigger diameters and under a high pressure, are not really flexible as one has to apply considerable bending forces to move them from the straight line. For bigger bending angles and numerous bending cycles there is the danger of fatigue failure. And it`s difficult to know, how much of the fatigue reserve you still have on your account. Hans Ulrich Ammann mailto:[EMAIL PROTECTED] http://www.spl.ch _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
