As luck would have it, I just bought a welder for my shop and I still have the receiving paperwork on my desk.... In Tucson AZ, USA. I bought two 125 cubic foot rated steel tanks for $196.10 US each. One filled with 75% Argon, 25% CO2 - the gas cost an additional $19.23 and the other filled with "pure" argon which cost an additional $17.89 As this is sold as welding shield gas, I'm going to assume "pure" is about 99.999%. Man, I really need to clean off my desk. -Denny On Fri, Nov 3, 2017 at 12:15 PM, Sean Breheny wrote: > Hmm, I wasn't aware that balloons used lower grade helium (in fact, based > on a quick Google search, it seems like they usually use the same grade a= s > is used for welding shielding gas, which is grade 5 (99.999%)) > > I don't think there is an inexpensive source of Krypton or Xenon. The > source for those gasses is the same as argon (fractional distillation of > ordinary air) and the abundance of Kr and Xe in air is extremely small, > whereas Ar is almost 1%. > > I bought an aluminum 2200psi, I think 40 cubic foot (at STP) cylinder of > ultra-pure Argon for about $130 at my local welding supply two years ago.= I > still have half of it. Most of that cost was the cylinder and valve. I > think a refill would be about $40. I had to purchase a regulator > separately. It is eventually going to be used to seal alkali metals > (sodium, potassium) in ampoules under inert gas. So far the only thing I > have done with it, which ended up using about half of the tank, was to do > an experiment to measure the density of Argon (I got a result which was > only a few percent off of the textbook value). It was good practice using > the flow-rate regulator, too. > > Even if you don't need pressure I would think that standard high pressure > tanks would be the most cost effective for you because of the quantity th= ey > can hold in a compact space. I chose to buy the tank but you can also ren= t > them for much less. > > Sean > > > On Fri, Nov 3, 2017 at 12:13 PM, Van Horn, David < > david.vanhorn@backcountryaccess.com> wrote: > > > I have local sources for helium balloons that use actual helium, not > > "balloon gas" so I pay about $1 for 2 or so liters of gas in a convenie= nt > > disposable container. > > I don't need pressure, I'm always pulling the gas anyway. > > My Neon and Argon come in glass flasks for $70/2l > > Still working on a cost effective source for Xenon. > > > > -----Original Message----- > > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behal= f > > Of Sean Breheny > > Sent: Friday, November 3, 2017 10:02 AM > > To: Microcontroller discussion list - Public. > > Subject: Re: [EE] Vacuum plumbing > > > > Is there any reason you don't use argon as your rinse gas? It's much > > cheaper. > > > > On Fri, Nov 3, 2017 at 11:15 AM, Van Horn, David < david.vanhorn@ > > backcountryaccess.com> wrote: > > > > > Fortunately my only use for helium is as a rinse gas. Vac the system= , > > > fill with He, then vac it again, and call it clean. :) > > > > > > -----Original Message----- > > > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On > > > Behalf Of alan.b.pearce@stfc.ac.uk > > > Sent: Friday, November 3, 2017 3:30 AM > > > To: piclist@mit.edu > > > Subject: RE: [EE] Vacuum plumbing > > > > > > > I still wish I could find a book/document/etc that describes the > > > > building of a vacuum system for the range of 1 torr to 10 microns o= r > > so. > > > > Seems to be a black art. > > > > > > Judging by the difficulties a program I am working on is having > > > sealing helium over a temperature range, it is very much a black art. > > > > > > Thankfully I'm only involved in the electricals ... > > > > > > > > > > > > -- > > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > > View/change your membership options at http://mailman.mit.edu/ > > > mailman/listinfo/piclist > > > > > > -- > > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > > View/change your membership options at > > > http://mailman.mit.edu/mailman/listinfo/piclist > > > > > -- > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > View/change your membership options at http://mailman.mit.edu/ > > mailman/listinfo/piclist > > > > -- > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .