chipgreen wrote:RJ, some ignorant layman-style questions about your lab analysis...
I noticed that the Convectron gauge is calibrated for N2, does this mean that N2 was displaced instead of O2 in the experiment? If so, and knowing that Oxygen is slightly heavier than Nitrogen how do you expect that difference would affect the overall numbers?
We use N2 as a purge gas for our thermal-vac chamber and these gauges only for rough vacuums as we transition to/from our mechanical roughing pump to either a turbo or diffusion pump. N2 is what, ~78% of our atmosphere. We are removing 'air'; ~78% N2, ~21% O2 and ~1% Ar. Being too lazy to actually calculate what the error may be I think at the pressures we are dealing with absolute error is negligible, the gauge just happens to be calibrated for N2.
Also, it appears that your numbers are converted to PSI and that the effectiveness of the gas displacement is based upon pressure change as opposed to actual volume displacement, is there a direct correlation?
We're not really 'displacing' gas here as much as removing some volume. My Argon rig actually does displace atmosphere with inert Argon that has a higher mass/volume than standard atmosphere, and covers the surface of the wine with a non-oxidative gas. Here I converted to psi for the masses that are most accustomed to dealing with those units. It was not convenient to attempt to measure volume, but perhaps pV = k could supply an approximation. The lab was 22C. Actual volume will obviously be affected by how full/empty your container is. I really think it's pressure we're interested in here.
Also curious if you did any additional pumping after the initial 20-25x on the Convectron gauge and remeasured to see if there was a difference in the reading? Would love to know the ideal number of pumps for this item since it does not have the tell-tale "click" of the Vacu-Vin which lets you know when to stop.
If you have/get one of these, there is a pretty obvious change in the tactile feel and sound as you pump down a bottle. One should have little difficulty knowing when effective pumping has ceased. The gauges confirmed minimal if any improvement when continued pumping sounds/feel were unchanged.
My apologies if my questions are silly due to the fact that my grasp on the subject material (particularly the research methods involved) may be lacking.
Thanks for your efforts!
Eh? Not at all. This was actually a hoot (woot!) and great diversion from what is normally a pretty mundane day.