VacuVin question

[Ajmassa]

9 ways to skin a cat is a great response. Couple of things to add. Isn't using a hand siphon the same as an AIO just not as safisticated. It's still a vacuum by gravity. Secondly and a different topic, does vacuum pumping also release the free sulfites as well?

Auto siphon same in principle? Not in this case because the main thing I'm focused is keeping the entire carboy under a sealed vacuum for an extended time period. Not just in the tubing.
No idea about the free sulfites, but I'm pretty sure if that WAS the case I would have heard that mentioned at some point before. Regretting all the goofing off I did in 11th and 12th grade chemistry and physics classes!

 

[mainshipfred]

The auto siphon was off topic. Just in general comparing the 2 methods of transfer and the introduction of O2. Still curious about the free sulfites though if anyone knows as I like the vacuum method as well.

 

[Johnd]

The auto siphon was off topic. Just in general comparing the 2 methods of transfer and the introduction of O2. Still curious about the free sulfites though if anyone knows as I like the vacuum method as well.

Quote out of an article by Tim Vandergrift in Winemaking Magazine, the article is on vacuum degassing:

"Finally, what about sulfite? It can be pulled out of solution by the action of vacuum. In this case, the answer is actually “yep, but.” You can lose one or two parts per million (ppm) of free SO2 to a strong vacuum over a period of hours. However, a couple of parts per million are beneath the ability of most home tests to measure, and not enough to warrant the addition of any extra sulfite to your kit wine."

 

[mainshipfred]

Thank you for that John. I guess I missed that article.

 

[AZMDTed]

BTW, this month's Winemaking magazine has another article on degassing, though it's not very thorough. He mentions the ability to lose SO2 while vacuum degassing but doesn't give anymore details. Also, it seems that Vandergrift isn't associated with them anymore. At least I haven't seen his name as a contributor since last May's conference.

 

[Ajmassa]

I thought he just recently had that blog through winemaker mag about the extended maceration? No?

 

[AZMDTed]

I thought he just recently had that blog through winemaker mag about the extended maceration? No?

He did blog on that, but that was on his own blog. In his last post on that in November he said he'd wait three months and do a taste test to see how it was going. I've been watching it closely waiting for that one. Not their yet. I haven't seen a Winemaking Mag blog from him since last summer.

 

[Hoxviii]

I've never been actually shown the 'proper' way to degas with VacuVin. Obviously there are 9 ways to skin a cat. And I've looked up videos but none are too detailed and each person has slightly different ways. Basically my new question has morphed to "when vacuum degassing(with any tool that gives a sealed vacuum) is it proper procedure to leave wine sit under vacuum for an extended time period after the remaining fizz has gone?"

the answer is "it depends". with a vacuvin, I'd sit there and baby sit it since you have no way of observing the vacuum stability so the only way you know degassing is occurring is by seeing bubbles.

If you have a proper vacuum pump with a gauge and valve to read your vacuum, I'd pump down to your target vacuum, close the valve, shut the pump off, and walk away.

Here's why:
if you apply vacuum above the wine it allows the CO2 to come out of solution. if you gradually leak vacuum over time back to atmospheric, the CO2 will go back in to solution; but without a gauge you'll never know if the bubbles are gone because the wine is fully degassed or if the CO2 went back in to solution due to vacuum loss.

With a gauge, you pull vacuum, note the vacuum you pulled, and walk away. check on it in an hour and if you're holding good vacuum that means you have a good seal, so you can walk away and check on it in a couple hours. As CO2 comes out of solution, your vacuum will decrease so you should expect to see a gradual loss in vacuum. When your vacuum stabilizes, that means no more CO2 is coming out, so you're fully degassed.

I'll qualify this with I've never vacuum degassed wine, so I have no idea how long it will take for the vacuum to decrease and stabilize - but this is what the physics of the situation say will happen with a dose of knowing how to work on vacuum based systems (AC and refrigeration)

 

[Hoxviii]

And you can figure out the maximum vacuum you can draw without messing up your wine by knowing the ambient temperature and the boiling point of ethanol under a vacuum.

Your vacuum gauge will read opposite this chart (so the top line reading of Hg (in) 30 actually = 0 vacuum, and the last line .8 =28.2 Hg(in) vacuum)

so at room temperature (20 degrees c = 68 degrees american) you can't exceed 27" mercury (30" minus 3") without boiling ethanol off of your wine.

 

[milant]

This has been a very thorough thread, but I do want to point out one thing that I don't believe anybody mentioned. With the VacuVin reasonably well sealed you will create lets call it vacuum (not exactly vacuum but negative pressure) after pumping the air mixture out of it. At that point the liquid will start releasing any excess CO2 and sulfites (former are larger bubbles, latter are smaller). As the gas is released into the head space the pressure differential will drop because the head space is now filling with CO2. Hence leaving the wine VacuVin sealed for a long period of time without additional pumping will yield little result.
For that reason, I leave the sealed Vacuvin on the carboy for about 2-4 days of degassing. At first I pump as much as the foam will allow but as the time progresses I pump more and often - every 4-6 hours as to keep a pressure differential significant leading to more degassing. Cracking the seal eliminates it, forcing me to pump more. All other things being equal, let physics work for you. I have found that in 4 days worth of "pumping" you have degassed the wine sufficiently.
Lastly, on the topic of wine re-absorbing the CO2, it is important to understand that substantial pressure is needed for the process. Temperature of liquid being reasonably stable, the CO2 released will extremely unlikely to produce such pressure without you having other problems. However, if the temp of the wine increases the CO2 will be absorbed easier. Point here: keep the wine at stable temperatures. But than again, that is one of the first rules of wine making to begin with.
Hope I helped. Cheers!

 

[Ajmassa]

Yes that was helpful. And leaving carboy under the VacuVin seal for days without additional pumping will not be releasing more CO2. That much is made clear.
And breaking the seal to make room for pumping out more CO2 is only harmful in that it will just require more pumping to re-establish the vacuum. So the initial question as to if it is ok to do this is yes, if you don't mind pumping more at first.
I asked this with scenario of a full carboy in mind. When additional pumping after manually releasing the CO2 fizz would be minimal. And when a significant amount of pumping to re-establish a vacuum each time would be deemed "not worth it" I would at that point leave the carboy sealed and then pump as needed for a few days.