Spunding for Dummies

[VikeMan]

Seems like a lot of you are using your spindijg valve to carbonate in the fermenter and then transfer the carbonated beer to the keg. Can anyone explain why? I thought the typical process was to ferment under atmospheric pressure, then transfer the beer with a few gravity points to go into the keg then close the keg and the spunding valve is there to bleed off any excess pressure in case you transferred it with too many gravity points remaining.

Personally, I don't spund to full carbonation levels in the fermenter. Think about autolysis, which "never" happens in homebrew. (Not really never, but people like to say it.) I think the reason it is so rarely happens to a noticeable level in homebrew is because yeast in homebrew fermenters doesn't normally see the kind of hydrostatic pressures that big (tall) commercial fermenters see. But when you increase pressure to the levels you need for carbonation, you're now exceeding what the tall (unpressurized) conicals see.

 

[bmullins393]

Personally, I don't spund to full carbonation levels in the fermenter. Think about autolysis, which "never" happens in homebrew. (Not really never, but people like to say it.) I think the reason it is so rarely happens to a noticeable level in homebrew is because yeast in homebrew fermenters doesn't normally see the kind of hydrostatic pressures that big (tall) commercial fermenters see. But when you increase pressure to the levels you need for carbonation, you're now exceeding what the tall (unpressurized) conicals see.

Curious.... what vessel do you use for pressure fermenting/spunding? Is it tall and thin like a corny keg? Or more squat like a flex or fermentasaurus? Does shape make the difference?

 

[VikeMan]

Curious.... what vessel do you use for pressure fermenting/spunding? Is it tall and thin like a corny keg? Or more squat like a flex or fermentasaurus? Does shape make the difference?

I ferment most batches in a MoreBeer 7.5 gallon conical, under low (~ 2 PSI) pressure, controlled by a spunding valve. The profile is more like a flex than a corny, but height doesn't really doesn't matter at that scale... the differences in hydrostatic pressure would be miniscule.

When I spund for carbonation, I do that in a corny keg.

 

[Vale71]

Personally, I don't spund to full carbonation levels in the fermenter. Think about autolysis, which "never" happens in homebrew. (Not really never, but people like to say it.) I think the reason it is so rarely happens to a noticeable level in homebrew is because yeast in homebrew fermenters doesn't normally see the kind of hydrostatic pressures that big (tall) commercial fermenters see. But when you increase pressure to the levels you need for carbonation, you're now exceeding what the tall (unpressurized) conicals see.

The tall conicals are pressurized up to 3 bar if doing warm lager fermentations. The reason they don't see autolysis is because they regularly dump yeast. The beer also gets packaged as soon as two weeks after pitching, which is the whole point of accelerated lager fermentation, so the yeast still in suspension has no time to start autolysing.
Autolysis happens simply because without nourishment yeast cells eventually die and decompose. This happens regardless of hydrostatic or headspace pressure. To actually start mechanically damaging yeast you'd need unbelievably high pressures or ultra-centrifugation. The reason most homebrewers don't detect autolysis is probably because they either can't or it's overshadowed by other, more promiment defects, first and foresmost cold-side oxidation.

 

[ChiknNutz]

Seems like a lot of you are using your spindijg valve to carbonate in the fermenter and then transfer the carbonated beer to the keg. Can anyone explain why? I thought the typical process was to ferment under atmospheric pressure, then transfer the beer with a few gravity points to go into the keg then close the keg and the spunding valve is there to bleed off any excess pressure in case you transferred it with too many gravity points remaining.

To clarify...I started in the fermenter with the spunding valve under low pressure (<5 psi), could have been 0 psi really. I was hoping that this low pressure would be enough to allow for a pressurized transfer but it is not. As @Vale71 noted, I would need more pressure and head volume to fully accomplish this. One reason I started with some pressure is based on the info I rec'd from the maker of this particular spunding valve, which I was not aware of until our exchange. In his listing he says to not started at 0 psi since the initial fermentation can actually create a vacuum, which I first questioned...below is his reply.

Yeast is one of a few microorganisms that can live:
1. Aerobically (in presence of oxygen) known as facultative phase when it consumes oxygen to reproduce - making more yeast.
2. Anaerobically (without oxygen) known as fermentative phase to make alcohol.
So right after adding the yeast, it will eat the oxygen in the headspace of the fermenter or about 20% of the air to make more yeast. That s how a vacuum will develop if everything is closed tight. Brewers need to have enough yeast for their fermentation, so they add oxygen to their wort by either inject pure oxygen or stirring/rocking vigorously to oxygenate it before pitching the yeast.
As soon as the oxygen is consumed, the yeast will switch to fermentative phase to make alcohol.
To avoid sucking in water from airlock or our FERMonitor, we recommend setting the pressure relief valve to about 2 psi (or 3 turns cw).

I then transferred to the keg at day 3 and cranked up the spunding valve to what you see in my latest post. At this point fermentation is slowing but the residual fermentation is what is creating the pressure so it can naturally carbonate. The keg is at ambient temp which is why you see it near 30 psi. Now at day 4-1/2 I just visually checked it before this writing and do have some airlock activity, as expected. I will leave this for probably another week so it can finish fermentation and fully carbonate. After this it can go in the fridge/kegerator.

 

[Vale71]

To put it somewhat bluntly: the manufacturer of this particular piece of equipment is full of it.
Yeast cannot consume the O2 that is in the headspace, the very idea is beyond ludicrous. Yeast don't have tiny lungs with which to inhale atmospheric oxygen, they'd have to wait for diffusion to transfer it to the liquid and that would take weeks if not months. That's why we aerate wort before pitching, because the O2 we dissolve in the wort is the only O2 the yeast will be able to absorb before switching to anaerobic fermentation, which wil produce copious amounts of CO2 that will gradually purge the headspace of any other gas.

 

[Yesfan]

So is it better to spund as fermentation starts to decline? I like the idea some of you are doing to use the fermenter's co2 pressure to purge your kegs but do you worry about any blow-off material getting through and possibly clogging the disconnect on your keg?

 

[ChiknNutz]

Well there you go. Not knowing all the particulars, I had no reason to question it at the time. Regardless, it is a quality product.

 

[Vale71]

So is it better to spund as fermentation starts to decline?

Definitely, unless your purpose is to do pressure fermentation and you know what you are doing and why.

 

[ChiknNutz]

...but do you worry about any blow-off material getting through and possibly clogging the disconnect on your keg?

Not if there is adequate head space. For me, I do ~5G batches (last one was likely 5.25G into the fermenter) and the fermenter is 7.6G capacity.

 

[VikeMan]

This happens regardless of hydrostatic or headspace pressure. To actually start mechanically damaging yeast you'd need unbelievably high pressures or ultra-centrifugation.

So you are saying that pressure doesn't matter at all vis a vis autolysis? Opinion or data?

 

[Yesfan]

Not if there is adequate head space. For me, I do ~5G batches (last one was likely 5.25G into the fermenter) and the fermenter is 7.6G capacity.

I've noticed bits of krausen in my blow off jar and that was with about 2-3 gallons of head space in my conical if you count the dome portion of the lid. I'm not so worried when most of the active part of fermentation has passed, but wonder with a pressurized fermentation from the start.

 

[VikeMan]

So is it better to spund as fermentation starts to decline? I like the idea some of you are doing to use the fermenter's co2 pressure to purge your kegs but do you worry about any blow-off material getting through and possibly clogging the disconnect on your keg?

There's nothing wrong with spunding (at low pressure) from the get go. But you do have to know your equipment, batch size, gravity, yeast strain behavior, etc. i.e. you need to be sure that there will be no blow-off, unless you want to ruin a spunding valve.

 

[Vale71]

So you are saying that pressure doesn't matter at all vis a vis autolysis? Opinion or data?

Not at the pressures that can be reached in beer fermenters. It's what's taught in all brewing schools so I'm pretty sure it's not uninformed opinion.
Mind you, excessive hydrostatic pressure will affect fermentation profile and performance, which is why even the largest industrial fermenters are limited to about 8 meters height. That and structural considerations, but not becuase of concerns with autolysis.

EDIT: Here is a research paper (only the abstract is free) on the subject of inducing autolysis in yeast to produce natural flavor enhancers for winemaking (autolysys is desirable and sought after in certain types of wine). The best results were obtained with a pressure of 150mPa or 21,755 PSI (that is not a typo!). This gives you an idea of how hardy the beasties are.

 

[bmullins393]

The tall conicals are pressurized up to 3 bar if doing warm lager fermentations. The reason they don't see autolysis is because they regularly dump yeast. The beer also gets packaged as soon as two weeks after pitching, which is the whole point of accelerated lager fermentation, so the yeast still in suspension has no time to start autolysing.
Autolysis happens simply because without nourishment yeast cells eventually die and decompose. This happens regardless of hydrostatic or headspace pressure. To actually start mechanically damaging yeast you'd need unbelievably high pressures or ultra-centrifugation. The reason most homebrewers don't detect autolysis is probably because they either can't or it's overshadowed by other, more promiment defects, first and foresmost cold-side oxidation.

Thanks for this info... I am learning...

What is Hydrostatic pressure? What effect does it have on fermentation under pressure?

Thanks!

 

[Vale71]

In any case, even though pressure is definitely a stress factor for yeast, it is by no means the only one.

Setting aside any quantitative considerations, saying "Pressure increases yeast autolysis. Pressure in our small unpressurized fermenters is negligible therefore we never experience autolysis in our home brews" makes as much sense as saying "Jumping off of a tall building means certain death. It follows that if you never jump out of tall buildings you'll live forever."

That is just wishful thinking on the part of the homebrewers. Autolysis is a part of the lifecycle of yeast (the terminal one, actually) and will happen in any case. There are many factors influencing the speed and the extent of it, such as yeast vitality, pitch rate, oxigenation rate and last but not least time and temperature. Anybody who thinks that it's safe to leave beer on a yeast cake for 6 months is just fooling themselves. On the other hand unpackaged beer will be so severely affected by oxidation after 6 months that autolysis probably won't matter anyway.

 

[Vale71]

Thanks for this info... I am learning...

What is Hydrostatic pressure? What effect does it have on fermentation under pressure?

Thanks!

It's the pressure you experience when immersed in a liquid that is proportional to the depth of immersion. To give a practical example, it's the pressure a deep see diver experiences during a dive.
Its effects on yeast are identical to the effects of headspace pressure since yeast cannot distinguish between the two types of pressure. In practice yeast will experience a total pressure that is equal to hydrostatic plus headspace pressure.
It affects yeast metabolism in several ways, first of all making it slower and then suppressing the production of aroma active substances like esters and fusel alcohols. Taken to extremes it can slow down yeast's performance to the point that you can get a stuck fermentation with possible stratification in very large fermenters, so that you could have fully fermented beer on top and only partially fermented beer in the bottom.

 

[Steven Barrett]

Assuming a 30 ft tall fermenter full of wort, the pressure at the bottom will be about 13 psi higher than the pressure at the top. Whereas if your fermenter is 3 ft tall, the pressure at the bottom is only 1.3 psi higher.

 

[bmullins393]

It's the pressure you experience when immersed in a liquid that is proportional to the depth of immersion. To give a practical example, it's the pressure a deep see diver experiences during a dive.
Its effects on yeast are identical to the effects of headspace pressure since yeast cannot distinguish between the two types of pressure. In practice yeast will experience a total pressure that is equal to hydrostatic plus headspace pressure.
It affects yeast metabolism in several ways, first of all making it slower and then suppressing the production of aroma active substances like esters and fusel alcohols. Taken to extremes it can slow down yeast's performance to the point that you can get a stuck fermentation with possible stratification in very large fermenters, so that you could have fully fermented beer on top and only partially fermented beer in the bottom.

Thanks so much for the great explanation. I had to read it twice but I got it now. I really enjoy the science of all this...

 

[bmullins393]

Assuming a 30 ft tall fermenter full of wort, the pressure at the bottom will be about 13 psi higher than the pressure at the top. Whereas if your fermenter is 3 ft tall, the pressure at the bottom is only 1.3 psi higher.

That makes sense... thanks!

 

[RePete]

This is all interesting. It is making me reevaluate my plans to buy a Kegmenter. They say that you can ferment under pressure in the Kegmenter, and then just serve from there without transferring to another keg...using a tube attached to a floating ball. Has anyone tried it here? I do question whether leaving the beer sit on the yeast is a good idea. Might work if you drink it right away.

As some of you, I had the idea that carbonation was in the primary fermentation vessel. If it is done after transferring to the serving keg, this means it may be more practical to go in another direction. Pressurized transfer was one of the draws too. But if transferring with gravity works as well? Currently I am carbonating in glass carboys. The auto siphon works, but I think I want to get something with a valve. Then can finish fermentation to carbonate in a corny keg.

 

[ChiknNutz]

I am using it strictly as a fermenter for now. The floating dip tube also helps to not move as much trub over to the keg, which is another benefit of the setup. I suppose it is on the expensive side as far as fermenters go. I chose this as it is SS so should last a lifetime and can use with pressure w/o worry whether for transferring or fermenting under pressure, etc.

 

[RePete]

It looks like a quality piece of equipment. And flexible as far as capability. Glad you like it. I’m just thinking for myself, and go back and forth on it. For the meantime I’m still using my carboys.

 

[ChiknNutz]

As far as expense, I just looked at the Fermzilla which seems popular and has the benefit of holding pressure as well. The price of that with the pressure kit is pretty comparable to the Kegmenter. You can harvest trub and/or yeast with the Fermzilla if that matters to you. For me, I so far like the Kegmenter being is it SS and will not be prone to scratching.

 

[RePete]

So, I ended up buying a 30L plastic Speidel fermenter. First, it was $100 less than a Kegmenter would have been. I like that it has carrying handles, a big opening for cleaning, and a valve at the bottom for taking samples and doing transfers. I'll just need to be careful cleaning it. I also bought a spunding valve for the keg.

I brewed an ale on Sunday, and was all set to try my first closed transfer this morning, then let the beer finish and carbonate the keg. But I sampled first, and it was down to 1.012 already. Probably finished, right? Or at least close to it. That was fast. 36 hours? I had pitched 2 packets of 04 dry yeast.

At this point, I decided to go ahead and dry hop in the fermenter. The recipe calls for it, but I was going to skip it in order to get the beer in the keg and try spunding.

I wasn't sure how to incorporate dry hopping with spunding. At least in the fermenter. It seems like if you are going to transfer the beer after initial fermentation, and hope to do spunding, you about have to dry hop in the keg.

I may just prime the keg with sugar, and use the spunding valve then.

 

[ChiknNutz]

I see your point about dry hopping and spunding. I have yet to do a dry hop batch, but I don't think you'd want to leave the hops in the keg indefinitely or you'll likely get too much hop flavor over time. Perhaps they are processes that cannot effectively coexist.

 

[RePete]

I see your point about dry hopping and spunding. I have yet to do a dry hop batch, but I don't think you'd want to leave the hops in the keg indefinitely or you'll likely get too much hop flavor over time. Perhaps they are processes that cannot effectively coexist.

I did a search, and people do dry hop in the keg. But you would probably want to drink it fairly soon. On this batch I planned to avoid it, and added extra hops at flame out. But then plans went awry. The sample tasted good, but I thought it could use more.

This might be an advantage of your Kegmenter. Dry hop under pressure in the fermenter, and then transfer.

 

[ChiknNutz]

...This might be an advantage of your Kegmenter. Dry hop under pressure in the fermenter, and then transfer.

Any idea if this complicates the transfer in any way? I thought I saw somewhere that transferring carbonated beer was somewhat problematic for some reason. Could be I mis-read that, not sure. If not, this would be my preferred method.

 

[RePete]

Any idea if this complicates the transfer in any way? I thought I saw somewhere that transferring carbonated beer was somewhat problematic for some reason. Could be I mis-read that, not sure. If not, this would be my preferred method.

I don’t know about transferring carbonated beer. Haven’t tried it.

 

[McKnuckle]

@ChiknNutz
Reviving this thread for a question on the SPUNDit, one of which I also have: How long does it take to build up even the least bit of pressure to register on the gauge? I'm having some challenges. Hopefully this isn't too long:

I pitched US-05 slurry at 69ºF in a keg of 1.045 ale. I daisy chained a second serving keg from the fermenter's gas port to the serving keg's liquid port. I attached a blow-off tube from the serving keg's gas port to a jar of Star-San. It was bubbling within 6 hours.

I took my SPUNDit and brought it out to my keezer, where I have beer on tap at 11 psi. I attached it to one of those kegs, and adjusted the dial until it held pressure. The gauge read 10 psi. I then removed the blow-off tube on my serving keg and attached the SPUNDit in its place. I figured that overnight, it would register some pressure.

Nope, no pressure registering on the gauge in the morning at all; it was pegged at zero (8 hours elapsed). So I put the blow-off tube back to check fermentation. Yes, plenty of bubbling. Then I put the SPUNDit back on and turned the dial all the way counter-clockwise to zero it out. Still no action in the small airlock. Then I put the airlock on the SPUNDit's accessory port, which is before the gauge and the pressure valve, therefore simply inline with the keg's gas port. Yes, it bubbles in that case.

So in short: The airlock bubbles when attached to a fully pressurized keg. It bubbles when attached to my fermentation setup, if it's on the accessory port. It does not bubble when attached to the normal output in that same scenario, even when dialed fully CCW.

I've been totally gentle with the device and have used it just a couple of times. I didn't physically damage it. Am I just being very impatient, and it takes a while to register even 1-2 psi of pressure on the gauge?

 

[RePete]

My first though reading this is just that if you have the Spundit attached to a secondary keg, it may take some time to build up pressure. You have what, 5 gallons of space to fill?

 

[Vale71]

Your keg is leaking without any internal pressure applied on the lid. It's unfortunately way too common with corny kegs and one of the major challenges they present when used as primary fermenters.

 

[McKnuckle]

The fermenter is a 3 gallon keg, and the serving is 2.5. There's no leak in either keg's lid. A simple blowoff tube works fine, as does the SPUNDit's airlock jar hooked to its accessory port, both in daisy chain configuration.

I'm just baffled by how long it's taking to register even 1 psi, and wondered about the norm (nobody seems to discuss the time required).

 

[Vale71]

The fermenter is a 3 gallon keg, and the serving is 2.5. There's no leak in either keg's lid. A simple blowoff tube works fine, as does the SPUNDit's airlock jar hooked to its accessory port, both in daisy chain configuration.

I'm just baffled by how long it's taking to register even 1 psi, and wondered about the norm (nobody seems to discuss the time required).

Yes there is, you're just not detecting it with the few millibar of pressure that a blowoff allows to build up. Go above that and you need a lot more pressure to push the lid in place to obtain a good seal, but you won't get that for several hours through fermentation alone and so CO2 keeps on escaping and the system is locked in a vicious circle that it's unable to exit.
If you have vigorous fermentation you should have registered plenty of pressure increase overnight, possibly even all the way to the set pressure.
To confirm you can apply 10 PSI of pressure with bottled CO2 and then attach the SPUNDit turned all the way up. If the kegs achieved a good seal you should see the pressure rising noticeably within the hour.
For reference, in a Unitank with plenty of head space when I spund in the evening I'll have reached at least 15 PSI come the following morning. Cold fermented lagers can take twice as much though as they tend to slow down a lot more than ales near the end.

 

[McKnuckle]

Yes there is, you're just not detecting it with the few millibar of pressure that a blowoff allows to build up.

Okay thank you, let's indulge this possibility... I filled the headspace of the fermenter keg with CO2 from my keezer setup, then I attached the spunding valve (turned up somewhere > 10 psi). The gauge is now registering 9 psi. I'm going to leave it this way and see if it climbs. So based on your example, which I appreciate, the pressure builds quickly - that's really the tidbit I was after.

 

[McKnuckle]

Alright, one hour later; I re-seated the fermenter keg's lid with some lube and the system is holding pressure. I was able to watch pressure climb by ~1 psi even over 20-30 minutes. Got it all going at 6.5 psi now. Thanks @Vale71 for your persistence in arguing for a small leak. Must have been so!

 

[ChiknNutz]

To add my $0.02, I have been fortunate I guess in that I had no issues using it so far. Normally I put the SPUNDIT on right after getting into the fermenter. I don't check to the next morning and have thus far always noted a pressure increase coupled with vigorous bubbling in the airlock. I have only 2 corny kegs, both new, and do not "pre-seat" them with pressure. I only add some keg lube to the seal and that has been adequate to ensure a good seal. I presume this changes over time given the comments from folks hitting them with pressure to ensure they are sealed.

 

[McKnuckle]

My kegs are not new, but I'm the original owner, and they are all lightly used. I take a long time to empty a keg, so I always re-apply lube with each new batch. On the fermenter keg, though, I was lazy this time, but lesson learned.

 

[RePete]

Glad you found out the problem. It does make sense. On some of my kegs, I have to give it a burst of CO2 to seal the lid. One thing I have found is that the seals which came with the kegs were harder. Whether from age or manufacturing, I don't really know, but I think they were just a lower grade of rubber. I found some new seals at the LHBS which work better.

 

[kmarkstevens]

Just posting so that this thread is easy to find.

David Heath Homebrew had a pretty good video on Spundit vs Blowtie: (11) Spundit V2 vs Blowtie Full Comparison for Homebrewers - YouTube