Taking gravity readings without compromising your brew

[mongoose33]

I've never worried about the air contaminating my beer when I take a sample. I'm more worried about what's been growing on my equipment for the past week or two than I am the air. Proper sanitization. I've never had an infected beer from the air after I've pitched yeast.

I wonder if the "danger" from airborne nasties contaminating our beer is related to where we live, and the time of year. I suspect in Nevada it's pretty dry and I'm thinking there might not be as many such threats. Compare to, say, Florida where stuff is growing at high humidity for most of the year--or the deep south.

I'm in Wisconsin so I wasn't quite as concerned during Jan-Mar when I brewed--nothing's growing! But once I hit the summer months, I'm very careful to cover my wort post-boil so little can settle in there.

Don't know if there's a study somewhere that discusses airborne yeast by region by time of year.

 

[jddevinn]

Concern with air is not primarily contamination but oxidation.

 

[DurtyChemist]

I wonder if the "danger" from airborne nasties contaminating our beer is related to where we live, and the time of year. I suspect in Nevada it's pretty dry and I'm thinking there might not be as many such threats. Compare to, say, Florida where stuff is growing at high humidity for most of the year--or the deep south.

I'm in Wisconsin so I wasn't quite as concerned during Jan-Mar when I brewed--nothing's growing! But once I hit the summer months, I'm very careful to cover my wort post-boil so little can settle in there.

Don't know if there's a study somewhere that discusses airborne yeast by region by time of year.

Possibly however I'd be willing to be there is just as much nasty stuff in our air than yours since 50-60% of yours is water and 20% of ours is water. Combined with 30-40F temperature swings it might be interesting to see what lives in desert air vs ocean air.

I also kept my brewing inside so I assume my air conditioning filter kept out as much as was safe to breath.

 

[jjeffers09]

"after half an hour" is the key. It takes me 2 minutes to pull a sample form a fermenter and close the lid. Diffusion takes TIME to do enough to be a worry at out brewing level. And you have an active ferment going on still adding more co2 as some diffuses so it offsets. It is NOT an issue on the scale we work at unless you are in he habit of leaving the lid off your fermenter for 30 minutes...

Wait that 30 min timeframe is for Br2 (a very heavy gas), not CO2... Diffusion of CO2 is much faster than 30 mins. However when the log phase is over and there is a lower production of alcohol there is also a lower production of CO2. When the air lock stops bubbling at a rapid rate and slows to ~20 bubbles a hour or 1 every 3 mins, or close to it. That is the time I check my beer. However, the CO2 will diffuse because of change in pressure also. That positive pressure build up will push CO2 out of the bucket. I think the best way is to work diligently. There is no reason to open the lid and walk away. Open the lid, pull the sample, pull the stopper/foil/lid over the vessel, drain the sample for your reading.

 

[hezagenius]

I filled my keg with CO2 first by starsan displacement and then fed the gas out back into the fermentor and created a closed loop system using gravity. of course I got a little air when I inserted the autosiphon. I pack a starsan soaked paper towel around the fermentor inlet also.

I like this idea. Just a question about how it works. After you push out the starsan solution, do you leave the keg with positive pressure? I'm guessing yes. Then use the positive pressure to push the gas back to the fermentor and that in turns pushes beer into the keg?

Since gas flows with less resistance than liquid, you'd need enough positive pressure to overcome that difference to get the beer flowing, right?

Once you get the flow going, you can release the positive pressure and let gravity do its thing?

 

[mongoose33]

I like this idea. Just a question about how it works. After you push out the starsan solution, do you leave the keg with positive pressure? I'm guessing yes. Then use the positive pressure to push the gas back to the fermentor and that in turns pushes beer into the keg?

Since gas flows with less resistance than liquid, you'd need enough positive pressure to overcome that difference to get the beer flowing, right?

Once you get the flow going, you can release the positive pressure and let gravity do its thing?

It's a helluva idea PlexVector had. I used it last night and it works great!

 

[hezagenius]

What is the order of how you connect the ends of the hoses?

 

[mongoose33]

What is the order of how you connect the ends of the hoses?

Assuming there's pressure in the keg, I start by putting my finger over the end of the gas tubing; install the QD, which releases the gas. I let a little go through the tube (purging it), then connect it to the top of the fermenter. What you see up there is an S-shaped airlock where I cut the top off, leaving a piece of the airlock that just fits nicely into the end of the tubing.

That should release gas into the fementer. If there's a lot of pressure you'll pop the lid or the stopper, be aware of that.

Once the pressure's equalized, attach the liquid-side QD, connect to the siphon or in my case spigot, and let 'er rip. I didn't purge the liquid line; I may determine an order in which to do that, but if you purge the keg after filling it, and noting that initially the air in the line is a tiny, tiny amount of the gas inside the keg, I don't see it as a huge issue.

 

[PlexVector]

I like this idea. Just a question about how it works. After you push out the starsan solution, do you leave the keg with positive pressure? I'm guessing yes. Then use the positive pressure to push the gas back to the fermentor and that in turns pushes beer into the keg?

Since gas flows with less resistance than liquid, you'd need enough positive pressure to overcome that difference to get the beer flowing, right?

Once you get the flow going, you can release the positive pressure and let gravity do its thing?

Having an autosyphon makes it not ideal,but I release most of the gas with the purge valve and the last little bit through the gas line before sticking in the top of the fermentor.

 

[dsniegocki]

Great job @PlexVector. I've got a thread where we go through a similar racking process, and the discussion about oxidation (as @jddevinn can attest) gets pretty contentious. But it's interesting stuff:

https://www.homebrewtalk.com/showthread.php?t=575247

 

[SGTSparty]

That's.....brilliant! Outgoing pressure balances incoming pressure. I'm going to do this.

I filled my keg with CO2 first by starsan displacement and then fed the gas out back into the fermentor and created a closed loop system using gravity. of course I got a little air when I inserted the autosiphon. I pack a starsan soaked paper towel around the fermentor inlet also.

Thanks. Since you have a spigot you can purge your gas-out line with residual keg pressure just before connecting it to the top of the fermentor. Completely closed gravity fed system.

Gents, your aside had me thinking. I use bottling buckets as fermentation vessels exclusively. Would this work type of system work doing the following:
Instead of hooking up to an auto-siphon I hook tubing to the bottling spigot (sanitized of course) then to the beer out QD. Take the Gas QD, run the tubing to the middle post of a 3 piece air lock similar to how some folks do blow off tubes?

In theory you'd get the CO2 from the keg pushing down on the top, and a combo of that pressure pushing and gravity pulling the beer into the keg. You'd have a close looped system so ideally very little O2 introduced (basically just whats in the lines) and very little possibility of contamination. I'm very intrigued by this.

 

[jddevinn]

Gents, your aside had me thinking. I use bottling buckets as fermentation vessels exclusively. Would this work type of system work doing the following:
Instead of hooking up to an auto-siphon I hook tubing to the bottling spigot (sanitized of course) then to the beer out QD. Take the Gas QD, run the tubing to the middle post of a 3 piece air lock similar to how some folks do blow off tubes?

In theory you'd get the CO2 from the keg pushing down on the top, and a combo of that pressure pushing and gravity pulling the beer into the keg. You'd have a close looped system so ideally very little O2 introduced (basically just whats in the lines) and very little possibility of contamination. I'm very intrigued by this.

Yes this would work, as long as you have no air leaks.

 

[SGTSparty]

Yes this would work, as long as you have no air leaks.

Cool, thanks. Even with airleaks it wouldn't be any worse than what I do now which is hook up a tube to the bottling spigot, run it down into an opened keg, pull the airlock out and open the valve. Right? Seems like a no brainer for the cost of 2 QD's and a run of tubing.

 

[mongoose33]

Gents, your aside had me thinking. I use bottling buckets as fermentation vessels exclusively. Would this work type of system work doing the following:
Instead of hooking up to an auto-siphon I hook tubing to the bottling spigot (sanitized of course) then to the beer out QD. Take the Gas QD, run the tubing to the middle post of a 3 piece air lock similar to how some folks do blow off tubes?

In theory you'd get the CO2 from the keg pushing down on the top, and a combo of that pressure pushing and gravity pulling the beer into the keg. You'd have a close looped system so ideally very little O2 introduced (basically just whats in the lines) and very little possibility of contamination. I'm very intrigued by this.

Pretty sure what you're describing is what I showed in post #36.

 

[SGTSparty]

Pretty sure what you're describing is what I showed in post #36.

Yeah, totally is. Sorry, I didn't see it. Should work the same w/ a 3 piece instead of an S shaped airlock right?

 

[mongoose33]

Yeah, totally is. Sorry, I didn't see it. Should work the same w/ a 3 piece instead of an S shaped airlock right?

I don't see why not. That 3-piece is easier for drawing beer samples out than the S-airlock, which you can't do that with.