Dry hopping / spunding

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk:

Murphys_Law

Well-Known Member
Joined
Apr 1, 2015
Messages
1,378
Reaction score
1,066
Location
Denver area
This may be addressed elsewhere, if so I apologize...

I am going to try my hand at spunding on my next beer and have a few questions re: spunding and dry hopping:

As I understand it, you transfer the beer from the fermenting vessel into a keg with ~4 pts remaining for natural carbonation. I assume you leave the keg at room temperature?? If so, would you set the PSI on your spunding valve to ~20ish if you are looking for 2.3 vols, assuming the room is mid-60's? After a period of time (how long?) you would then place the keg in the keggerator to get to serving temp and hook it up to your CO2 at say, 12 PSI??

What about dry hopping? I usually dry hop with a few points left so where/how would this fit into the above spunding schedule? I assume you could put your dry hops in the spunding vessel but how would you best do an O2 purge on this keg before transferring from fermenter to spunding the vessel? Simply fill with CO2, purge...repeat?

And then you would probably want to move beer from spunding/dry hop vessel to serving keg, but since this beer is now carbonated are there any foaming issues when going from one keg to serving keg?

I currently fill the keg with sanitizer (I use saniclean due to low foam) and then purge the solution to another keg, then closed transfer from my Fermonster into the serving keg.

And a somewhat random thought/question: What about cold crashing? Does anyone dry hop/spund/cold crash or do you "cold crash" when you put the serving keg into the keggerator?

Or am I just overthinking this! o_O
 

Big Monk

Trappist Please! 🍷
Joined
Dec 24, 2015
Messages
2,192
Reaction score
1,140
As I understand it, you transfer the beer from the fermenting vessel into a keg with ~4 pts remaining for natural carbonation. I assume you leave the keg at room temperature??
You let it finish at fermentation temperature. When you spund you are not finished with primary fermentation yet.

If so, would you set the PSI on your spunding valve to ~20ish if you are looking for 2.3 vols, assuming the room is mid-60's?
Use the carbonation tables to find out the proper PSI setting for your fermentation temperature.

After a period of time (how long?) you would then place the keg in the kegerator to get to serving temp and hook it up to your CO2 at say, 12 PSI??
When it reaches final gravity. You only want enough pressure from bottle gas to serve the beer.

What about dry hopping? I usually dry hop with a few points left so where/how would this fit into the above spunding schedule? I assume you could put your dry hops in the spunding vessel but how would you best do an O2 purge on this keg before transferring from fermenter to spunding the vessel? Simply fill with CO2, purge...repeat?

And then you would probably want to move beer from spunding/dry hop vessel to serving keg, but since this beer is now carbonated are there any foaming issues when going from one keg to serving keg?
I'm not a kegger so i'll let others chime in, but I will say that dry hopping is a tough nut to crack for low oxygen brewing. Using extracts dosed inline when transferring is a great way to accomplish the required flavors. I do know that many people at our site dry hop quite frequently, but I can;t quote thier methods offhand as I don't keg or brew beers that required dry hopping.
 

SanPancho

Well-Known Member
Joined
Dec 17, 2014
Messages
2,587
Reaction score
764
Location
An Island in the Bay
personally- id get the pressure kit for fermentasaurus. you could dry hop and spund at same time, with only one chance of getting o2 exposure. then just go from the fermenter into your purged keg. keep the psi differential between fermenter and keg to under 5psi to keep foaming down. or lower if you dont mind going slowly.

the other option is to add the dry hops and some sugars (dextrose, table sugar, saved wort) into the purged keg as fast as you can- with co2 blowing into the keg while the lid is open to keep o2 out- and then transfer on top of that from the fermenter.

in short, there's probably a dozen ways to do it. you just gotta decide what's most important to you- timing, o2 minimizing, ease/simplicity, etc. you could spend hours reading everyone's techniques.

but if you spund in the keg, do NOT leave your spunding device attached. they're all pretty crappy and they often leak, you could lose your co2. and yes, at room temps you need to be in the 20s for psi. better to wait at least 2-3 days and then check the pressure with a gauge, and only put on the spunding device once the keg reaches your desired pressure.
 

h22lude

Well-Known Member
Joined
Dec 27, 2010
Messages
3,425
Reaction score
434
Location
lincoln
You can use CO2 from fermentation to purge a keg. Sanitize it, hook the blow off tube to the beer out post and another tube from the gas in post to a jar of sanitizer. Add your dry hops to that keg. The CO2 from fermentation will purge the keg. You now have a purged keg with hops in it. Only issue is the hops will be exposed to O2 for the few days it takes to purge the keg. I'm not sure how that would affect them.
 

MSK_Chess

enthusiastic learner
Joined
May 22, 2017
Messages
698
Reaction score
258
Location
Glasgow, Scotland
The issue of purging using bottled CO2 I feel is not a problem. Ok pure natural CO2 is best, no one denies but any oxygen that is present in bottled CO2 is parts per billion! If it freaks you out then fine, find another solution, personally I am not phased by it at all. If I was dry hoping I would get a hop basket and purge a Keg and do a closed transfer, panic over, problem solved. As h22lude states, if you want to use only natural CO2 then you could purge a keg using bottled Co2 with your hops in it and purge it again with natural Co2 for a couple of days, only I would keep it cold. Not a fan of hop extracts, I think you can tell the difference a mile away from whole natural hops.
 

Die_Beerery

Banned
Joined
Aug 21, 2017
Messages
842
Reaction score
639
Parts per billion (100 to be exact), is the concentration in beer that causes accelerated staling. I can even detect a difference in product between spunded keg beer, and canned beer at 22ppb. So it certainly matters.
 

MSK_Chess

enthusiastic learner
Joined
May 22, 2017
Messages
698
Reaction score
258
Location
Glasgow, Scotland
I do not spund but transfer from primary to keg, closed and under pressure into a purged keg. I don't have any qualms about using Co2 to push beer from primary to keg, infact for me there is no other way. Beer rarely if ever lasts more than two months after fermentation at which point its just getting good. I don't think I have ever had a beer that's tasted stale to be honest or at least not that I was able to notice.
 
Last edited:

h22lude

Well-Known Member
Joined
Dec 27, 2010
Messages
3,425
Reaction score
434
Location
lincoln
The issue of purging using bottled CO2 I feel is not a problem. Ok pure natural CO2 is best, no one denies but any oxygen that is present in bottled CO2 is parts per billion! If it freaks you out then fine, find another solution, personally I am not phased by it at all. If I was dry hoping I would get a hop basket and purge a Keg and do a closed transfer, panic over, problem solved. As h22lude states, if you want to use only natural CO2 then you could purge a keg using bottled Co2 with your hops in it and purge it again with natural Co2 for a couple of days, only I would keep it cold. Not a fan of hop extracts, I think you can tell the difference a mile away from whole natural hops.
The problem with using bottled CO2 to purge a keg is it will take a lot of purging to fully purge the O2. You would need 20 full purge cycles at 15psi to get O2 under 200ppb. To get as close to 0.00 as possible you would need to go up to 25psi. To me, that is a waste of CO2. Plus a lot of time just sitting there purging a keg. The few purge cycles that most people do barely removes any O2.
 

MSK_Chess

enthusiastic learner
Joined
May 22, 2017
Messages
698
Reaction score
258
Location
Glasgow, Scotland
The problem with using bottled CO2 to purge a keg is it will take a lot of purging to fully purge the O2. You would need 20 full purge cycles at 15psi to get O2 under 200ppb. To get as close to 0.00 as possible you would need to go up to 25psi. To me, that is a waste of CO2. Plus a lot of time just sitting there purging a keg. The few purge cycles that most people do barely removes any O2.
Ok then, perhaps we could wait until our fermentation is vigorous, purge the keg using natural Co2, open it (say on day two) put in our hop basket, close the keg, let it purge for some more (say another two days) do a closed transfer for spunding and proceed as normal.
 
Last edited:

SanPancho

Well-Known Member
Joined
Dec 17, 2014
Messages
2,587
Reaction score
764
Location
An Island in the Bay
If you can get your fermenter to hold 1-2 psi then you fill the keg with water and let the fermenter push the water out. Youll get like 1 or 2 psi back pressure on fermenter which is fine, and slowly drain the keg. Way better o2 removal than high pressure purging and the co2 is free.
 

SanPancho

Well-Known Member
Joined
Dec 17, 2014
Messages
2,587
Reaction score
764
Location
An Island in the Bay
Also- the trick with hop extracts is to not use them alone. Much better when paired with actual hops, which rounds out the one-dimensional aspect of extracts.
 

h22lude

Well-Known Member
Joined
Dec 27, 2010
Messages
3,425
Reaction score
434
Location
lincoln
If you can get your fermenter to hold 1-2 psi then you fill the keg with water and let the fermenter push the water out. Youll get like 1 or 2 psi back pressure on fermenter which is fine, and slowly drain the keg. Way better o2 removal than high pressure purging and the co2 is free.
No need to fill it with liquid. The co2 from fermentation will purge the keg by itself. This method removes 100% of the air in the keg and replaces it with co2 from fermentation which is pure co2 (unlike bottled co2).
 

whovous

Waterloo Sunset
HBT Supporter
Joined
Dec 20, 2013
Messages
1,450
Reaction score
267
Location
Washington


For easy math take a 1.050 beer with 85% Attenuation. That will produce 15cuft of pure co2. 15cuft = 424.753 liters = 112.2078718 gallons of CO2 from ferment... So enough to fill 22.45 5gallon cornies.
I am not real clear just how you are converting cubic feet of gas to gallons of liquid. I don't think the math works the way you say. One cubic foot of liquid does equal roughly 7.5 gallons of same, but that tells us nothing about gas, does it?
 

h22lude

Well-Known Member
Joined
Dec 27, 2010
Messages
3,425
Reaction score
434
Location
lincoln
Ill let the physics nerds here debate you, but no it doesnt.
Here you go

https://www.homebrewtalk.com/forum/threads/keg-purging-with-active-fermentation.628658/#post-8004741

And from University of Missouri. .5 cubic meters of CO2 would fill two bath tubs. It just so happens that Bryans example uses 15 cubic feet which is almost .5 cubic meters. So the co2 produced by a 1.050 would fill two bath tubs.

Sorry, it isn't letting me upload from my phone. I'll do it when I get home.
 
Last edited:

Big Monk

Trappist Please! 🍷
Joined
Dec 24, 2015
Messages
2,192
Reaction score
1,140
Don’t get too bogged down by the math. It’s a lot of CO2. There is a reason why big breweries capture their fermentation CO2.

We can’t capture it and store but we can certainly use it to our advantage for purging and carbonating our beer.

EDIT: I misspoke: the math is important. The physics of it all is important. I just wouldn’t rack my brain trying to crunch the numbers.
 
Last edited:

whovous

Waterloo Sunset
HBT Supporter
Joined
Dec 20, 2013
Messages
1,450
Reaction score
267
Location
Washington
I get bogged down once we start using the term "gallons." That is a liquid measure. Liquid measures are finite, but gas expands to fill a space. Seven gallons of a gas does not mean a lot to me.
 

MSK_Chess

enthusiastic learner
Joined
May 22, 2017
Messages
698
Reaction score
258
Location
Glasgow, Scotland
Agreed, we are civilised people and should only deal in litres, metres, grams and Celsius. The French even tried to make time metric, but sadly it didn’t work.
 

Die_Beerery

Banned
Joined
Aug 21, 2017
Messages
842
Reaction score
639
I get bogged down once we start using the term "gallons." That is a liquid measure. Liquid measures are finite, but gas expands to fill a space. Seven gallons of a gas does not mean a lot to me.
OK.
 

Die_Beerery

Banned
Joined
Aug 21, 2017
Messages
842
Reaction score
639
We are talking CO2 in gaseous form, are we not? How much gas can you put in a seven gallon jug? As temperature and pressure vary, doesn't the answer change as well?
We are, you are correct. Hence my OK. I will chime back in when I finish that measurement.
 

h22lude

Well-Known Member
Joined
Dec 27, 2010
Messages
3,425
Reaction score
434
Location
lincoln
Here is the blurb from University of Missouri regarding how much space 1kg of CO2 takes up. It just happens to line up perfectly with Bryan's example.

How much volume does 1 kg of CO2 occupy at room temperature and standard pressure? CO2 has a molecular weight of 44 g/mol 1 kg CO2 = 1000 g × (1 mol/44 g) = 22.7 mol CO2 V=nRT/P, V=(22.7)(0.0821)(300)/1 = 559 L CO2 at 27°C (300K), 1 atm This is a little more than half a cubic meter approximately equal to the volume of two bathtubs or the trunk of a large car.

.5 cubic meters is 17.5 cubic ft (close enough to 15 cubic ft). 17.5 cubic ft lines up with about a 1.055 beer. So a 1.055 beer would produce enough CO2 to fill two tubs. I think we can safely say a 1.050 beer would pretty much do the same.
 
OP
Murphys_Law

Murphys_Law

Well-Known Member
Joined
Apr 1, 2015
Messages
1,378
Reaction score
1,066
Location
Denver area
Who would have thought ya start out to make beer and end up in a science class! :D
 

gifty74

Well-Known Member
Joined
Mar 2, 2009
Messages
374
Reaction score
49
Location
Lancaster, PA
And then you would probably want to move beer from spunding/dry hop vessel to serving keg, but since this beer is now carbonated are there any foaming issues when going from one keg to serving keg?
I've been through this, and think I have a good solution. A few batches back I converted to naturally carbing and it noticeably changed my beers, for the better, without a doubt. It's SOOOO much easier if you don't have to dry hop, but let's face it, most of us will want to do that if we brew and IPA, so we need a solution, right??!

I did not have much luck with transferring to the keg and trying to time it to have the last few points of fermentation happen in the serving keg (ie. the stated "Spunding" method). This method gets much more complicated when you throw dry hopping into the mix, when do you add them, how do you get the hop matter out, etc.

So, I dry hop (first dry hop) my beers in the carboy adding the dry hops near the end of fermentation. However, I also like to do a second round in the serving keg. So, you transfer from carboy to serving keg and take all the care to minimize splashing.

SIDEBAR: I don't use the 'fill with water to the max, push out with co2' method to purge out the serving keg before transfer. I look at lowDO overall, and especially this part of it, as a balance of time/hassle vs. reward. Amount of hassle it takes to get a discernible change / improvement. I've tried it, and it was a pretty big PITA to get all the lines set up, wasted water, wasted co2... With the o2 that you are gobbling up by natural carb method (keep reading), you don't need to worry about the o2 you get at this point from the transfer. Now, it might make a difference (maybe noticeable, maybe not) on the really super light lagers where o2 contamination can really be felt, but with the beers I brew, I have not seen it.

Add your calculated amount of priming sugar for the volumes of co2 you want in the finished beer based on the temp you will be naturally carbing at (charts will tell you grams of corn sugar). Put in the dry hops in a bag or SS canister and tie with fishing line or string to the inside of the corny keg lid (all sanitized of course). Fill & purge with co2 8-10 times to get as much of the headspace o2 out as possible (even though you are mixing co2 & o2 (and other gases) you are still getting as much co2 as is reasonable). Now, I'm sure the lowDO truists will say this is 'incorrect'. I beg to differ. I do not have scientific data, but real IPA flavor stability to go off of. You still have all of the natural carbonation process to eat up any o2 that you might have introduced as part of the transfer and 2nd dry hopping. This also makes it MUCH simpler because you're not relying on a very flakey spunding valve (which almost all have issues) to regulate pressure. You are using a calculated amount of corn sugar that is known to give a very accurate level of co2 once naturally carbonated. So all you really need is a "T" with a pressure gauge to confirm that the pressure is building and getting to the level its supposed to based on the co2 charts. After 5-7 days pull the poppet to relieve the co2 pressure in the headspace and carefully remove the dry hops. Carefully removing them will limit any agitation of the co2 blanket, and you'll still have another week or so of naturally carbing to gobble up any o2 that would've gotten in (which is minimal). Put the lid back on (don't even need to fill/purge) and continue to monitor pressure and it should be all good to go after another 1-2 weeks of natural carbonating and when you see no more pressure building. For me, that's around 26-30 psi. Now, take it from one who has learned, DO NOT try to get the lid off at room temp after finishing natural carb. TOO much co2 in solution and if you try to get the lid off without chilling it first, it will be impossible, and once you do get it off, a gallon of beer will come rolling out as the co2 tries to quickly get out of solution. Chill to serving temp, put on some co2 pressure from your bottle, and tap it. You'll get a little sediment at first, but your liquid dip tube will quickly form a little pocket and only pull freshly hopped beer!

Use this method to resolve the issues you are bringing up. To answer your question, yes, you will have major foam issues if you try to transfer a beer, at room temp, to another vessel if it's anywhere near the amount of co2 you want in solution per most any style. It would have to be done at serving temps, you need another sanitized vessel, another chance for o2 to be introduced...lots of issues doing it that way.
 
Last edited:

Unicorn_Platypus

Urine I Pee... Eh?
Joined
Oct 13, 2012
Messages
387
Reaction score
121
Location
NYC
You can use CO2 from fermentation to purge a keg. Sanitize it, hook the blow off tube to the beer out post and another tube from the gas in post to a jar of sanitizer. Add your dry hops to that keg. The CO2 from fermentation will purge the keg. You now have a purged keg with hops in it. Only issue is the hops will be exposed to O2 for the few days it takes to purge the keg. I'm not sure how that would affect them.
I like this idea! I'm thinking you could also purge the headspace a few times in the receiving keg (after adding hops)and the fermentor (assuming you are using one that holds pressure like the fermzilla) at pitching. As long as you dose the wort with pure O2, there should be enough dissolved in solution to fuel primary fermentation even if purging the headspace.

Still in the process of setting up my new rig, but plan to give this a shot when I'm ready. Historically, I've been purging the receiving keg 5x from a CO2 tank after adding the hops and have had great success with that method.
 
Top