What is the CORRECT way to displace ambient air from headspace ?

[Fox Squirrel Vin]

For a doofus like me, what does 0.01% of an atmosphere translate to in inches mercury ? I'm at sea level if that matters ... obviously a rough number is fine since here I am in my barn ...

One atmosphere is just under 30 inches of mercury so a reduction to .01% would be .03 inches of mercury at seal level. A vessel evacuated to that level of vacuum would experience about 14.7 psi of pressure on its entire surface.

Another way to think about it is, if you had 100 cubic inches of air, that vacuum level would remove 99 cubic inches leaving the gasses in 1 cubic inch of air at one atmosphere to fill the void left by the removal of the other 99.

 

[sour_grapes]

For a doofus like me, what does 0.01% of an atmosphere translate to in inches mercury ? I'm at sea level if that matters ... obviously a rough number is fine since here I am in my barn ...

That is funny! I expressed it as a percentage because I thought that would be more accessible than inches of mercury!

@Rice_Guy and @Fox Squirrel Vin covered the concept. (Although the actual numbers would be 0.003 inches of Hg, and, in Vin's second example, there would be 0.01 cubic inches of air left from the original 100.)

This level of vacuum is what we call "rough vac."

 

[sour_grapes]

Argon is useful for displacing air from the headspace. However, there is no "blanket" effect. Gases will freely mix on the timescale of minutes. Any oxygen left in your headspace will have unfettered access to the wine. Although Argon is heavier than N2 or O2 (and lighter than CO2), this does not have an appreciable difference: the kinetic energy of the molecules completely dominates the potential energy due to gravity. At equilibrium (i.e., after ~10 minutes), the distribution will be very nearly uniform. The difference in composition due to Ar being heavier shows up in about the 5th decimal place.

 

[Fox Squirrel Vin]

That is funny! I expressed it as a percentage because I thought that would be more accessible than inches of mercury!

@Rice_Guy and @Fox Squirrel Vin covered the concept. (Although the actual numbers would be 0.003 inches of Hg, and, in Vin's second example, there would be 0.01 cubic inches of air left from the original 100.)

This level of vacuum is what we call "rough vac."

Correct, I take no responsibility for pre-caffine posts and calculations from percentages to decimal at 6 am in the morning.

 

[Fox Squirrel Vin]

Argon is useful for displacing air from the headspace. However, there is no "blanket" effect. Gases will freely mix on the timescale of minutes. Any oxygen left in your headspace will have unfettered access to the wine. Although Argon is heavier than N2 or O2 (and lighter than CO2), this does not have an appreciable difference: the kinetic energy of the molecules completely dominates the potential energy due to gravity. At equilibrium (i.e., after ~10 minutes), the distribution will be very nearly uniform. The difference in composition due to Ar being heavier shows up in about the 5th decimal place.

Of course. Oxygen can enfusse through cork and wood too. But the key point is, you are not going to have a significant amount of diffusion of oxygen into wine when you have covered the wine with argon. Blanket is a poor choice of words for some but not all. The amount of oxygen that will diffuse into wine will depend on the amount of oxygen that has diffused into the argon. If the tank is purged from air by displacing it with argon at filling to say... a volume of 100 cubic inches and your airlock sucks in .5 Cubic inch of air which contains 1/10th of a cubic inch of oxygen and that completely diffuses into argon, the concentration is so low that its ability to greatly affect the quality of the wine is nothing anyone can taste and it certainly isn't going to affect the quality.

And that is the point.

Richard, we are discussing wine-making here not trying to prove or disprove Fick's law.

 

[CDrew]

Argon is useful for displacing air from the headspace. However, there is no "blanket" effect. Gases will freely mix on the timescale of minutes. Any oxygen left in your headspace will have unfettered access to the wine. Although Argon is heavier than N2 or O2 (and lighter than CO2), this does not have an appreciable difference: the kinetic energy of the molecules completely dominates the potential energy due to gravity. At equilibrium (i.e., after ~10 minutes), the distribution will be very nearly uniform. The difference in composition due to Ar being heavier shows up in about the 5th decimal place.

Preach on brother...

The "blanket" mythology of argon is strong. But that does not make it true. And thank goodness. If it were true, at sea level we would have only argon to breathe since it makes up about 1% of atmospheric air! For short periods, flushing with an inert gas likely does displace some air lowering O2 content a bit and temporarily, and is better than nothing. But it isn't a long term solution.

 

[Fox Squirrel Vin]

Preach on brother...

The "blanket" mythology of argon is strong. But that does not make it true. And thank goodness. If it were true, at sea level we would have only argon to breathe since it makes up about 1% of atmospheric air! For short periods, flushing with an inert gas likely does displace some air lowering O2 content a bit and temporarily, and is better than nothing. But it isn't a long term solution.

Boy we are just in physics class today and removing all common sense and removing the factors the OP laid out and what we are suggesting to do to mitigate the problem as relates to wine making.

We are dealing with a tank (A CLOSED ENVIRONMENT) that has a large volume of headspace, coming up with solutions to reduce oxygen diffusion into wine.

Maybe you scientists can check my edits to see if they are more to your liking so we can move on from the class on Fick's law and get back to suggestions that will solve the problem.

 

[sour_grapes]

I certainly agree that:

Argon is useful for displacing air from the headspace.

 

[Hesster1977]

Holy cow, all of this discussion makes me wonder just HOW to rack 5-1/2 gal of mead from my primary bucket to my 5 gal Carboy, and minimize oxygen. Obviously avoid splashing , and minimize head space. But for those of us who are not about to spend a ton of money on CO2 tanks, regulator’s, plumbing, etc. , there has to be a simple “good enough” approach we can follow w/o being a Physics major. How about siphon carefully, and use a simple Sodastream CO2 carbonating unit to give any headspace a purge shot, then bubble lock it? Looking for a simple practical solution.

 

[OilnH2O]

I could not see in any other post you've made how long you intend to leave wine stored in these vessels?

Are you using these for primary AF only? Long term storage...

I was interested to see what Mike suggested, after he posted above. Mike is highly experienced in small batch stuff but is also the "industry" guy (he's a research chemist) you were wondering about earlier. Maybe he'll jump back in...

 

[chonn]

My conclusion (I'm the OP) is as follows:

1. Liberally pour in co2 (or Argon) through the bunghole like I always have

2. Quick, slam in a stopper that has TWO holes - one of which is pre-plumbed with a second co2 tank that is ALREADY FLOWING ... and continue to overflow co2 out the other hole in the bung stopper

(at this point I probably have 95% co2 in the headspace ... and rising, since I continue to flow through the bung stopper)

3. turn on my pump

4. Insert pump line into second hole of the bung stopper and turn OFF the tank

5. vacuum to 20", turn tank back on and refill back to 0"

(repeat step 5 2-3 more times)

6. clamp both lines, walk away

I'm only going to vacuum to 20" because I don't need to stress the container and I don't need to run the pump an extra X minutes and I am starting with (probably) less than 5% ambient air to begin with ... after two reps of this I'll bet I am 99.5% co2 ... maybe I'll do a third rep for good measure or maybe I'll do the first rep to 25" ... but I don't think I am going to pull it all the way to 30" ....

Thank you very much for these comments and guidance!

 

[sour_grapes]

Holy cow, all of this discussion makes me wonder just HOW to rack 5-1/2 gal of mead from my primary bucket to my 5 gal Carboy, and minimize oxygen. Obviously avoid splashing , and minimize head space. But for those of us who are not about to spend a ton of money on CO2 tanks, regulator’s, plumbing, etc. , there has to be a simple “good enough” approach we can follow w/o being a Physics major. How about siphon carefully, and use a simple Sodastream CO2 carbonating unit to give any headspace a purge shot, then bubble lock it? Looking for a simple practical solution.

But your situation doesn't pose a problem. You will be able to fill your carboy with the mead. The amount of oxygen exposure during racking is not enough to be concerned about. It is the situation of long-term storage with headspace that poses the oxidation risk that this thread was trying to address.

 

[Vic Frohmeyer]

OK, many interesting responses - thank you.

First of all, the containers I use are these stainless steel primary fermenters:

https://www.amazon.com/gp/product/B018J82JOY/
They are 14 gallons in size. There are not 11 or 12 or 13 or 13.5 gallon sizes so no matter what I am going to have 1 or 2 or 3 gallons of headspace. Note: they are perfectly airtight - gasketed with 5 clamp locks and I have tested several of them with fine vacuum gauges over months and they lose no vacuum. So they are tight.

This is a single vintage, single vineyard product I am making and my 400 grapevines make what they make - if it comes out to 11 gallons that is what it comes out to.

Yes, certainly I could get a 7 gallon fermenter like this, and a 5 gal carboy, and then ... mix and match containers like that but not only does this diminish any real value in bulk aging prior to bottling it also adds more reps and more variables AND dosing and measuring additives like KMBS or acid are double the work and different calculations, etc.

So the bottom line is, the 11-13 gallons that my vineyard makes is going into one final container - this one.



Yes, this is where I am going as well ... although you're saying start with 100% ambient air and cut it by halves with each rep - I would be more aggressive and dump co2 into the headspace initially, like I have been, AND THEN cycle the vacuum/co2 for a few reps.

So instead of 50 -> 25 -> 12.5% ambient air, I would be going 5% -> 2.5% -> 1.25% ... (assuming I had only 5% ambient air initially).

... which means a second hole drilled and cleaned up (and gasketed) on the lid. That's pretty easy and I can vacuum test it with water and air for a month and be sure it doesn't leak.

Here are some closing thoughts:

1) I would, still, really like to hear from some lab tech somewhere - or some industry tech - not connected to winemaking. How do people do this in a lab ? I don't think they're using plastic baggies. They MIGHT be using a co2 generator like dry ice but, again, I'd love to hear something that sounds like "the real way people do this".

2) It seems to me that there is a difficult valley between very small production (2-5 or even 9-10 gallons) and, say 500 or 1000 gallons. Everyone knows exactly and perfectly how to deal with one or two carboys. At the same time, I think the pros at big wineries have very nice (and very expensive) methods of dealing with 500 or 1000 gallons. But if you have 15-30 gallons you're stuck (re)inventing things.

Does that ring true to you ?

From a "not connected to winemaking" background, (pharmaceutical manufacturing), most of the bulk raw material storage tanks, work in process and finished goods liquids that had atmospheric sensitivity were inert gas purged and blanketed continuously. The main gas we used was nitrogen. Smaller bulk tanks were plumbed to gas cylinders through regulators and .2 micron filters before going into the tanks. The bigger tanks were supplied with large pad mounted nitrogen generators, similar filtration. The QA/QC labs did the same on a smaller scale. All of the gasses used were high purity. Cylinders came with C of A's, bulk generation systems were validated and continuously tested. In general, Rice_Guy's response above is very close to what we did in our configurations. Remember, you don't need much pressure, just enough to reliably displace air and keep it out of your set up. Given your fixed volume of storage, and your need for single vintage batch integrity, inert gas over the liquid surface is probably going to work the best for you (from a not connected to winemaking perspective).

 

[Raptor99]

It seems like it would be a lot less work to just rack it into smaller carboys.

 

[Fox Squirrel Vin]

From a "not connected to winemaking" background, (pharmaceutical manufacturing), most of the bulk raw material storage tanks, work in process and finished goods liquids that had atmospheric sensitivity were inert gas purged and blanketed continuously. The main gas we used was nitrogen. Smaller bulk tanks were plumbed to gas cylinders through regulators and .2 micron filters before going into the tanks. The bigger tanks were supplied with large pad mounted nitrogen generators, similar filtration. The QA/QC labs did the same on a smaller scale. All of the gasses used were high purity. Cylinders came with C of A's, bulk generation systems were validated and continuously tested. In general, Rice_Guy's response above is very close to what we did in our configurations. Remember, you don't need much pressure, just enough to reliably displace air and keep it out of your set up. Given your fixed volume of storage, and your need for single vintage batch integrity, inert gas over the liquid surface is probably going to work the best for you (from a not connected to winemaking perspective).

Nitrogen generators are the bomb, hook then to an air compressor and you have nitrogen on tap, Nappa uses them extensively in the aging process. So much more cost effective than Argon once your volume gets to their level but they typically are only producing a 99.5% pure gas. Obviously that .5% of air in the mix is not detrimental to the final product.

 

[winemaker81]

Boy we are just in physics class today and removing all common sense and removing the factors the OP laid out and what we are suggesting to do to mitigate the problem as relates to wine making.

Winemaking is not exempt from the natural laws of physics and chemistry. Solutions that don't actually work are placebos.

 

[winemaker81]

Holy cow, all of this discussion makes me wonder just HOW to rack 5-1/2 gal of mead from my primary bucket to my 5 gal Carboy, and minimize oxygen. Obviously avoid splashing , and minimize head space. But for those of us who are not about to spend a ton of money on CO2 tanks, regulator’s, plumbing, etc. , there has to be a simple “good enough” approach we can follow w/o being a Physics major. How about siphon carefully, and use a simple Sodastream CO2 carbonating unit to give any headspace a purge shot, then bubble lock it? Looking for a simple practical solution.

O2 exposure is another widely misunderstood point in winemaking.

Oxidation is a factor of wine volume vs headspace (or exposure) vs time. Oxidation does not happen quickly -- racking wine under normal conditions is not dangerous. Rack efficiently and minimize air contact without going gonzo, and the likelihood of problems from O2 exposure are close to zero.

This is one of many good reasons to add K-meta -- SO2 binds to contaminants, rendering them harmless. This includes incidental O2 exposure.

 

[Rice_Guy]

In the scheme of things industrial wine racking introduces in the range of 0.5 mg/liter oxygen. Quiescent/ no splashing home racking should be in that range and metabisulphite addition sequesters most of the oxygen. ,,, We live with it.
Most taste panels will identify acetaldehyde (oxidized ethyl alcohol) at 100ppm. At low levels acetaldehyde adds complexity/ an interesting tingle/ long flavor notes like apricot juice would in a blend. ,,, We live with some acetaldehyde.
HACCP/ risk evaluation:
In comparison an average bottling line will introduce 5 mg/liter. A bad bottling line can easily double that and home bottling which doesn't nitrogen flush or vacuum cork probably is significantly worse. ,,,, We talk about bottle shock as “normal” then add 50 ppm meta and tolerate this because we don’t have home scale tools to do better.
The OP looked at two gallons of ullage with eight gallons of wine. Representing roughly 1.14 gram O2 with 30.3 liters of wine or 37.7 mg O2 per liter.
Risk is relative, ,,,, anyone with two ounces of ullage in a five gallon of mead is OK but half a gallon ullage in half a gallon jug of mead will taste the problem.
Six months in a LDPE (rated 100 cm3 O2 / meter2) cubitainer/ milk jug with no ullage you will taste it. PET (rated <1) over six months you won’t taste it. ,,, and a week in the LDPE zero ullage cubitainer will also be good. Risk is cumulative, like spending the pay check.

Holy cow, all of this discussion makes me wonder just HOW to rack 5-1/2 gal of mead from my primary bucket to my 5 gal Carboy, and minimize oxygen. Obviously avoid splashing , and minimize head space. But for those of us who are not about to spend a ton of money on CO2 tanks, regulator’s, plumbing, etc. , there has to be a simple “good enough” approach we can follow w/o being a Physics major. How about siphon carefully, and use a simple Sodastream CO2 carbonating unit to give any headspace a purge shot, then bubble lock it? Looking for a simple practical solution.

 

[Hesster1977]

So I racked yesterday an had a little more head space in the Carboy than I was hoping for. Since this will be a sparkling mead, no meta or sorbates. I borrowed a idea to use my Sodastream with a hose from it to the Carboy cap and gave it a big blast of ice cold CO2. You could see it cause it was so cold it was cloudy. Then quickly bubble locked and capped it. Good as it’s gonna get!

 

[QuiQuog]

Man, I hate to be that guy, because I'm not answering the question you asked, but like others have suggested, how hard do you want to work for a problem with a ready-made, time tested, really simple solution? You have a 14 gallon container and want to eliminate 2-3 gallons of airspace. That equates to one 6 and one 5 gallon carboy, and possibly a 1 gallon jug.

As an experiment for your amusement, go haywire and plumb for pumping gasses and measuring atmosphere. You risk equipment failure, power outages, or miscalculations, and will spend all that time fiddling with it. It may be a great feeling when it succeeds.

If you want to try and ensure success, get the carboys.