Vacuum Pump Degassing Methods

[Chiumanfu]

I'm experimenting with different methods of degassing wine with a vacuum pump and I'm interested in hearing what you guys do and what may work better than others.

Method 1 - Splash racking. I see the majority of videos on youtube of people splash racking to rack and degas at the same time. I've never tried but I can see the potential of a lot of oxidation.

Method 2 - Holding a vacuum. Pull 20-24inHg and leave it for a certain period. How long do you usually need? What are the signs that the degassing is complete?

Method 3 - Tube clamp. Shown here
[ame="http://www.youtube.com/watch?v=rUJ5rYeBR3w"]http://www.youtube.com/watch?v=rUJ5rYeBR3w[/ame]
I like this one because you can kill two birds with one stone (racking and degassing) and it seems like oxidation is minimal but how effective is it at removing CO2?

Thoughts, comments?

 

[pjd]

#1 If you are splash racking under vacuum, there is no oxygen in the recieving carboy so oxidation is not a problem. #2 this method, depending upon time will degas but will also boil away the alcohol. #3 from the video, it appears to be effective but other than the clamp is the same as #1 which is also effective.
Made a great visual anyway.
Phil

 

[robie]

I don't know the exact point, but you have to pull a much larger vacuum to get the alcohol to boil.

Method #1 can introduce a little oxygen because it is already present in the receiving carboy. Some of it gets vacuumed out, but there is going to be some. Still, I like this method for racking right after secondary fermentation is completed. For subsequent rackings, I don't splash rack.

I don't fully understand the last method (#3). I guess you are letting only a small amount of wine through the clap, so it causes some turbulence at that point. Seems like that would cause the CO2 to turn loose really well. Shouldn't be any oxygen left in that tube after a few seconds of vacuuming with the clamp. I just have never tried it. This does look interesting.

After the racking is over, I like to leave the vacuum going directly on the receiving carboy. This way, if there is any air introduced, it can't stay in the wine any more than the CO2 can.

Degassing is done when you see no more bubbles coming up out of the wine. I like to hold a vacuum for at least 10 minutes after all bubbles stop.

 

[vacuumpumpman]

#1 If you are splash racking under vacuum, there is no oxygen in the recieving carboy so oxidation is not a problem. #2 this method, depending upon time will degas but will also boil away the alcohol. #3 from the video, it appears to be effective but other than the clamp is the same as #1 which is also effective.
Made a great visual anyway.
Phil

I must agree with Phil - I do not understand how you can see the potential of a lot of oxidation only for #1 and not for #3 ?

I also know of people who have filled their carboy with co2 prior to transfering - so that there is defintley no oxygen at all,
I think anyone can turn a good thing to obsession . not saying that is bad
I also will upload some pics, just using #1 and it appears that there is alot of co2 showing
I just figured it out - with the clamp on you are restricting the flow of wine ,which in affect raises the vacuum in the receiving carboy -- correct ?

which I am assuming that you are around 24''hg on an empty carboy ?

 

[Wade E]

I have to jump in here and ask, while vacuum racking and say the carboy being filled is 1/4 full, what is exactly in the rest of the carboy?

 

[BobF]

I have to jump in here and ask, while vacuum racking and say the carboy being filled is 1/4 full, what is exactly in the rest of the carboy?

It's the 'aether', Wade!

 

[Chiumanfu]

I just figured it out - with the clamp on you are restricting the flow of wine ,which in affect raises the vacuum in the receiving carboy -- correct ?

which I am assuming that you are around 24''hg on an empty carboy ?

It's not my video so I'm not sure on he specifics. I just thought it was an interesting method and was wondering what you guys thought.

I think what is happening is, the point where the clamp is pinched creates a transitional area of very quick drop in pressure. This agitates the CO2 out of the wine. It should be happening in complete absence of oxygen therefore limiting exposure.

It does look quite violent though and MartyYule's point of treating the wine gently has merit.

 

[robie]

The more I look at it I think it is not the Co2 you see but the Wine boiling from the increased vacuum at that constriction. I don't think it is a drop in pressure but an increase in vacuum. If that wine is actually boiling then the wine is being ruined before your eyes. To go a step further even though this flies in the face of common practice there are those who believe that you should not draw wine through a filter for the very same reason. Wine should be pushed or pumped only. Now many of us use vacuum to filter and we seem to do it without problem but there is a science here that at least theoretically should be considered. I will leave it to the physics majors to sort this one out.

I don't remember the actual value, but I think it takes several more inches of vacuum to boil alcohol, than most of us use for degassing and racking.

Alcohol boils at 173F. You would have to draw enough vacuum to lower that significantly, in order to get alcohol to boil at room temperature. I just don't know the math.

However, that sudden pressure change at the clip-on might have some sort of influence in the formula.

 

[TJsBasement]

Mother earth news, no link cause its about dis!!!!!!! But they say m@$h will boil at 125F under 22" of merc.

 

[vacuumpumpman]

Mother earth news, no link cause its about dis!!!!!!! But they say m@$h will boil at 125F under 22" of merc.

Altitude is also a big factor as well

 

[Chiumanfu]

I don't think it is a drop in pressure but an increase in vacuum.

That is the same thing!

Ethyl alcohol boils at 79 C under standard atmospheric pressure at sea level which is 29.92 inHg

I've found two calculators and both give similar (though not identical) answers so I expect they are somewhat accurate.
http://www.calctool.org/CALC/chem/substance/boiling
http://www.trimen.pl/witek/calculators/wrzenie.html

Take the first calculator.
Boiling point is = 79 degrees C
at pressure = 29.92 inHg
Pressure y = 4.92 inHg (25 inHg vacuum)

Boiling temp. at pressure y (25 inHg vacuum) = 29.12 degrees C (84.4 degrees F)

At 20 inHg vacuum, the boiling temp of the alcohol is 48.5 degrees C (119.3 degrees F). Most of the systems I've seen can pull somewhere between 20-25 inHg vacuum.

I think we are safe unless your wine is very hot or you're pulling crazy high vacuum (>27 inHg).

 

[BobF]

Venturi anyone?

 

[BobF]

I'm thinking all CO2. Where would the air come from?

 

[Chiumanfu]

Good call BobF. You guys are so smart!

The venturi shape created by the clamp will increase the speed of the wine through that point and thus decrease the pressure (increase the vacuum). Theoretically the wine could be at the choke point where the speed of the wine through the constriction approaches the speed of sound. The exact formula to determine the vacuum at the orifice of the venturi is extremely complicated and beyond me but the vacuum does have the potential to be very very high.

I think this method may be more violent than we thought. It could be flash vaporizing all kinds of stuff.

 

[Chiumanfu]

In my opinion, I do not believe that the venturi effect applies to the whole house filter. In the case of a clamped off hose, the venturi orifice is true. In the case of a filter, the orifice is the combined sum of all the tiny little pathways and that sum is large enough that the venturi effect will not be significant.

[ame]http://youtu.be/XzfLipeZidk[/ame]

 

[vacuumpumpman]

What kind of vauum are you pulling ? It seems not to be alot at all, the only reason I say that it took so long to do a transfer.
Does it remove CO2 while just doing a normal transfer ?

What micron filter were you using when this was filmed ?

and yes I did come up with the idea od threadding the pipe into the filter housing. I can show pics and why - latter when I get home tonight ,if anyone is intrested ?

 

[BobF]

Well a very respected Commercial Winemaker wrote this.....Cavitation is simply boiling the wine at ambient temperature due to drawing the wine into a low pressure area from a higher pressure. The wine in front of the filter is at "high" pressure and you are sucking it through the filter which is restriction. This means the wine behind the filter will be at a much lower pressure. As it comes through the filter and at other points in the low pressure side, the wine will essentially boil. You know water boils at a lower temp at altitude, right? A similar thing is happening here. This is VERY simplified but I hope it helps illustrate why wine should not be sucked through a filter.

Truly simplified ...

What happens when wine is pumped with an impeller pump?

Cavitation is exactly what happens with a drill mounted whip, "vigorous" stirring with a spoon/paddle, etc. The rapid pushing of the spoon through the wine creates low pressure behind the spoon. This is true in all cases EXCEPT while inside The Matrix where there is no spoon. ;-)

The difference I see is that with a pinched tube (or any other similar device), the wine isn't in the presence of large volumes of air.

As far as the filter goes, the entire housing creates the venturi effect regardless of cartridge parameters. And it doesn't matter whether the wine is being pushed or pulled.

I've spent some time with a well-respected researcher at the local university research winery. For whites, he actually sparges with nitrogen to create the turbulence required to get the CO2 out of the wine. He does this by injecting nitrogen into the transfer line during pumping ops.

One day I will likely spring for a nitrogen setup for carboy/bottle flushing and will definitely try degassing via nitrogen sparge.

Don't get me wrong, vacuum works far better than any of the mechanical means I've tried, but I have had batches that were extremely stubborn about giving up CO2. Mechanical action is the only thing that worked for them, and nitrogen sparge is about the most O2-free method I've heard of to agitate wine.

 

[BobF]

I've heard the theory about time taking care of CO2. It probably works better in barrels. IME, a carboy with an airlock does NOT give up CO2 naturally with time. At least not reliably. Some do, some don't. My working theory is that wines with higher TDS give up CO2 more readily due to greater nucleation opportunity. And there's the rub ...

There are two distinct, popular reasons for degassing. One is to facilitate clearing. One is to achieve the proper level of CO2 for the finished wine.

Common wisdom, as shared, is to degas young wine ASAP to get the wine clear ASAP. Not bad advice on the surface, but I think few appreciate how long fermentation continues -slowly- beyond the second racking or so.

Where am I going with this? IMO, an early round of degassing can cause problems later. If the wine isn't -really- done fermenting, degassing and racking to remove suspended solids will actually make it harder to remove the newly generated CO2 later.

Anyway, I've had too much product, so I'm carrying on.

Bottom line is that I've had wines hold on to CO2 for a very long time in carboys. I would say indefinitely, but I'm not willing to hold 30 bottles more than 18mos to make -that- claim.

 

[BobF]

That's great for you - congrats!

 

[Chiumanfu]

What kind of vauum are you pulling ? It seems not to be alot at all, the only reason I say that it took so long to do a transfer.

I had it set to about 18 inHg. It took 5 mins 30 seconds to move 23 liters.

Does it remove CO2 while just doing a normal transfer ?

It does degas during transfer if there is high CO2 saturation and I run the vacuum higher.

What micron filter were you using when this was filmed ?

5 micron