Vacuum degassing - How much vacuum should I pull and why

[winedegasser]

The reason why degassing is important in home wine brewing is that during the fermentation process of wine making, carbon dioxide is released and dissolved in the fermented juice. Vacuum is a very effective way to extract Co2 from the wine. But how much vacuum should we pull? Too low it won't work effectively. Too high alcohol will start evaporating and it will decrease the ABV (alcohol by volume) value of wine.

To get the number correctly we need to understand
1. The relationship between temperature and gas solubility
2. The relationship between pressure and gas solubility
3. The relationship between pressure and liquid boiling point

Generally speaking
1. The lower the temperature of the wine becomes, the more carbon dioxide dissolves.
2. As the pressure in the container decreases, the solubility of carbon dioxide in wine decreases.
3. The lower the pressure is, the lower the boiling point is.

1. and 2. mean that at a lower temperature, we need to pull more vacuum to effectively degas the wine. 3 means that if we pull TOO much vacuum (pressure is too low), the wine will boil and evaporates

The following table shows you the boiling temperatures at different vacuum pressure (Source CalcTool)

So at 23 Celsius (74 Fahrenheit), -20" can be used to pull the Co2 out without affecting the ABV (alcohol by volume).

If you are interested to know more details about the scientific backgroud please check Wikipedia
Henry's law: http://en.wikipedia.org/wiki/Henry's_law
Solubility: http://en.wikipedia.org/wiki/Solubility#Temperature
Degasification: http://en.wikipedia.org/wiki/Degasification

 

[winedegasser]

I got some questions about if -25 inHg is safe for the carboys. Frankly speaking, I don't have any scientific proof to say that it is. Neither do I have any proof to say that it is not.

I recommend that all my customers to pull NO MORE than -20 inHg because the quality of carboys are different.

However, I have 5 glass carboys, and I degas in my garage, which is between 10 to 18 Celsius, or 50 to 64 Fahrenheit. I've been degassing using them at -26 for over two years now and never had problem with any of them. Mind you, they are all good quality, thick and heavy carboys I bought from good reputation stores. e.g. they are not made in the other end of the world.

And every time I used them for degassing (VERY important), I checked see if there's any cracks/chips. Also (EXTREMELY important) I topped it up at least to the curve edge of the carboy.

 

[saramc]

I guess my issue is that if you are selling this tool and supplying temps/pressures yet have NO DATA to backup the safety of these methods you better hope you have some major liability insurance. I can so see lawsuits happening based off of the advice your provide. If you do not know, you should NOT be advising others. Poor business practice in my opinion.

 

[jimmyjames23]

I get good results with -18" Hg. Takes a few days under held vacuum. Though I watched a friend implode a 54L demijohn with a pump capable of -30". I don't know if it was pulling that much when it caved. I'm pretty sure the thinner glass and heavier mass were contributing factors.
That and the Demi was probably older than me.

 

[vacuumpumpman]

I guess my issue is that if you are selling this tool and supplying temps/pressures yet have NO DATA to backup the safety of these methods you better hope you have some major liability insurance. I can so see lawsuits happening based off of the advice your provide. If you do not know, you should NOT be advising others. Poor business practice in my opinion.

Good point Sara
I had to go thru extensive insurance liability questions, and approx 8 years of research and development as well. The biggest thing is to make the process of winemaking easier - especially people who have bad backs or other disabilities. But the whole time I have to think about the safety of my customers which always come first. That is why my customer support is so high in my priority

 

[winedegasser]

I guess my issue is that if you are selling this tool and supplying temps/pressures yet have NO DATA to backup the safety of these methods you better hope you have some major liability insurance. I can so see lawsuits happening based off of the advice your provide. If you do not know, you should NOT be advising others. Poor business practice in my opinion.

You are absolutely right!

I will take out those numbers and advise all my customers that they should only pull -20 inHg. Thank you SOOOOO much for reminding me!!!

 

[vacuumpumpman]

You are absolutely right!

I will take out those numbers and advise all my customers that they should only pull -20 inHg. Thank you SOOOOO much for reminding me!!!

Winedegasser

I hope you have Liability Insurance ?
Is it also good for the United States - unless you specifically ask for it - you most likely are only insured for the country you reside in

 

[winedegasser]

Yes the same applies to you too

Because -22 may be too high to some carboys and you don't have any data to back it up either. In fact, nobody does.

Winedegasser

I hope you have Major Medical Insurance ?
Is it also good for the United States - unless you specifically as for it - you most likely are only insured for the country you reside in

 

[vacuumpumpman]

The question is do you have liability insurance for anyone who purchased your product ? I hope so

 

[Chiumanfu]

How did this become a discussion on America's obsession with law suits? This mentality is the main reason why North America is losing it's technological edge.

Winedegasser. Thanks for the chart. You clearly show the boiling point of the ethyl alcohol component of the wine, but I think at higher vacuum levels, there is more to consider. Who knows?...All the volatile compounds that make up the bouquet of the wine could be easily vaporised as well. For that reason, I prefer to use as low a vacuum as possible for as short as possible and prefer grasshoppers falling film technique.

 

[Pumpkinman]

I think this is absolutely a question of liability...let me explain, if I am purchasing a product I want to know that the manufacturer has done their due diligence to not only protect me but to know that they comprehend their own products and their limitations, anything less is just a gamble, I don't want to know that the manufacturer is conducting his tests on us.... this raises more than one red flag.

 

[pjd]

Wow! We got us a pissing contest here! One vendor whose machine sucks and another vendor whose machine blows! ok, vacuum pump versus air compressor. This will be fun to watch!

 

[Pumpkinman]

Phil,

One vendor whose machine sucks and another vendor whose machine blows!

you make this sound like two negetives..... This is very important for fellow members to know which machine has been tested and has the proven track record to stand behind the claims.
I get very nervous if a vendor does not know the limitations or thresholds of its own products.
We all work too hard to waste money on the hope of a product working well, only to find out that the manufacturer changes their recommendations in each thread.... if you don't know how much pressure is too much when selling a vacuum pump, it's time to go back to the books and get nthings right before you harm someone, "oppps, thanks for reminding me just doesnt cut it".

 

[pjd]

Phil,
you make this sound like two negetives..... This is very important for fellow members to know which machine has been tested and has the proven track record to stand behind the claims.
I get very nervous if a vendor does not know the limitations or thresholds of its own products.
We all work too hard to waste money on the hope of a product working well, only to find out that the manufacturer changes their recommendations in each thread.... if you don't know how much pressure is too much when selling a vacuum pump, it's time to go back to the books and get nthings right before you harm someone, "oppps, thanks for reminding me just doesnt cut it".

Tom, I said that totally tongue in cheek! I own the all in one and it is a good machine. I just thought it was funny watching the sniping going on. Basically I agree with you. I did not mean this to sound negative it was just humor!

 

[Pumpkinman]

Phil,
Sorry Bud! As a business owner, I get caught up in trying to make sure winemakingtalk members are aware of what is factual. I apologize if I have offended you.

 

[winedegasser]

Wine Degasser has been tested over 30 times on 5 different carboys that I have at -25" (room temperature 10C / 50F) and all worked fine. I have youtube video to back it up.

However, I can only test it on MY carboys, not all the other carboys in the world.

So when I sell it I lowered the recommended vacuum to -20".

Make sense?

 

[winedegasser]

Wow! We got us a pissing contest here! One vendor whose machine sucks and another vendor whose machine blows! ok, vacuum pump versus air compressor. This will be fun to watch!

For the record, I am providing those numbers as a reference for all members who vacuum degas their wine, NOT just wine degasser users.

You can DIY your own pump, buy a hand vac, buy all-in-one, or my degasser. They all do the job. No matter what you choice is, I hope this information can be helpful for you.

I believe it's not just about making money, it's about making money and having fun and making things easier (Thx Brew & Wine Supply)

 

[Brew and Wine Supply]

Don't think anyone has mentioned you're Canadian, except for a question on shipping. Where did that come from? The last two words sum it up "Having fun" and I'll ad in making things easy

 

[winedegasser]

Sorry if I offended you in anyway. I just meant to say I am too focusing on the having fun part, not the making money part. I have to admit that I am not very good at promoting my products...

Don't think anyone has mentioned you're Canadian, except for a question on shipping. Where did that come from? The last two words sum it up "Having fun" and I'll ad in making things easy

 

[REDBOATNY]

Thanks for the data. We all know the risk with whatever we chose to use for vacuum transfer, not to mention the integrity of the vessel we are putting under vacuum.