On 11/01/2012 11:17 AM, jb-electronics wrote: > Hi again, > > I made some tests with my vacuum system today: I opened the ball valve > and let the pump run for two hours straight. After about ten minutes, > the pressure arrived at 9E-3mbar and stayed there for the rest of the time.
Jens, When I was building my metal neon manifold (and later when I started making them for others), I experimented with just about every valve format I could get my hands on. Rule of thumb is, if it has packing it will leak vacuum. My solution was refrigeration diaphragm valves. http://www.neon-john.com/Neon/Shop_equip/Metal_Manifold/Metal_Index.htm This type of valve transmits the force of the closing stem through a stainless steel diaphragm to the actual valve mechanism. There is no packing to leak. The only minor downside to this type of valve is that it has a small bit of polymer in its seat. This absorbs moisture when the system is at atmospheric pressure. Under vacuum it takes about a day to outgas. You'll notice a couple of packed needle valves on the gas metering part. I could get away from that by putting the SEAT toward the vacuum and the packing side toward the always-pressurized neon and argon sources. Plus those are nuclear grade double-packed valves. John -- John DeArmond Tellico Plains, Occupied TN http://www.fluxeon.com <-- THE source for induction heaters http://www.neon-john.com <-- email from here http://www.johndearmond.com <-- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
