Kegging in a vacuum

[grohr]

Am a heating and air tech. My question is if there are any HVAC techs that brew, have you ever pulled a vacuum on a keg ( negative pressure ) to fill it from a Carboy or a bucket? This would result in no oxygen in keg, theoretically no need for co2 and it would suck the beer into it. Any thoughts on this would be great.

 

[thadass]

If only kegs were designed to hold a vacuum instead of positive pressure!

I would think that the level of vacuum a keg could hold, along with the maximum vacuum required to prevent excessive foaming of the beer (it will already have some CO2 in it and placing it near a vacuum would have this effect I expect) would not be any faster than utilizing gravity to rack.

Very interesting idea though. I always assumed all pro breweries would use gravity and pumps, but I wonder if any are successfully using vacuum to move things.

 

[chocotaco]

My thoughts are, if you have a keg you probably have CO2. Why not just use the CO2?

 

[grohr]

I have a vacuum pump that I use on big commercial rooftop units pulling a vacuum down to 800 to a thousand microns, it will suck a 30 pound jug of liquid refrigerant in a heartbeat into the rooftop unit. Just thinking that the transfer of beer into a keg without filling the headspace with CO2 would possibly be better? And I was wondering if that would also help to preserve beer in a keg for a longer amount of time before you tap it? Just a thought.

 

[thadass]

I have a vacuum pump that I use on big commercial rooftop units pulling a vacuum down to 800 to a thousand microns, it will suck a 30 pound jug of liquid refrigerant in a heartbeat into the rooftop unit. Just thinking that the transfer of beer into a keg without filling the headspace with CO2 would possibly be better? And I was wondering if that would also help to preserve beer in a keg for a longer amount of time before you tap it? Just a thought.

The answer to all of this (even the questions you didn't ask) is CO2. Be nice to your beer!

In reality though, for preservation, CO2 is the best and most important thing you can make sure of to improve shelf life. Some say that a beer that has been cold crashed/fined might age better, but I'm not sure. As always stronger flavors and alcohol levels age better, and hop aroma fades quickly no matter what.

 

[grohr]

Cool, I'll remember that. Good input. I won't be experimenting with a vacuum pump anytime soon. I will do research about this and get back to everybody to see if there is any benefit in it.

 

[BeerGrylls]

The valves, seals, and poppits are designed to hold positive pressure, not negative. If you put a vacuum on it, the air will just rush back in from any of your PRV, dip tube posts, or lid hatch.

 

[passedpawn]

Dang, I misunderstood the topic. I thought someone else tried a wet/dry sour.

 

[WissaBrewGuy]

Unfortunately the other posters kind of have a point here. As an HVAC engineer I would be all about using a vacuum pump to transfer beer but I don't think the kegs (especially the PRV which will never let you pull a real vacuum) could handle it. Just to entertain the idea because it would be cool say you had a vessel that was designed for a vacuum: as thadass points out, I think there will be some crazy foaming or some other reaction due to there being a headspace void of air in the vessel but there is CO2 dissolved in the beer. I believe that everything is worth experimenting with so here is my proposal: fill one keg with very lightly carbonated water, then transfer it via vacuum and see what happens. If it goes smoothly and dispenses ok then you could try it with a beer that you are not too proud of if you know what I mean. Good luck!!

 

[insanim8er]

Dang, I misunderstood the topic. I thought someone else tried a wet/dry sour.

Funny thing is.... this is what I was thinking when I saw the title. haha

 

[Bobby_M]

There's no reason why you couldn't pull a light vacuum on a keg to rack out of a carboy but it's not true that this would be without oxygen exposure. For one thing, you don't want to try putting 0 Hg on the keg to remove the oxygen so there would be oxygen left in the keg. Also, in order to let the liquid flow out of the carboy, it will be sucking in outside air into the headspace. It's best to flood the keg with Co2 to purge O2 out, then push the beer out of the carboy with a small bit of CO2 added to the headspace.

 

[zachattack]

As others have mentioned, corny keg seals (really just the lids, since presumably the QDs will be attached so poppets are out of the equation) are only designed to seal under positive pressure. If you try to pull a vacuum, air will just get sucked in around the lid.

If you wanted to replace the lid with a vacuum-rated one, I see no reason why it wouldn't work, but it does seem unnecessary and overly complicated to me. I've posted this in other threads, but if you're really interested (and already have the vacuum pump lying around) you can buy lids that are rated for vacuum. I'm not sure what size you'd need for a corny keg, but at work I use corny-like pressure vessels from Alloy Products Corp, they sell vacuum lids that look like this, but they're around $50:

 

[ChuckO]

Aside from the difficulties in sealing a keg for less than atmospheric pressure, I would not want to remove the CO2 already in solution in the beer. When you finally go to putting the keg on pressure you would have to replace all of the CO2 that you removed while transferring to the keg.