Walk me through keg spunding please

[Rob2010SS]

I want to start keg spunding so I want to make sure I have it right and I have some questions.

Im pretty sure I have it down in determining WHEN to transfer to keg so FOR THE DISCUSSION, I'm going to start with assuming transfer to the keg took place with ~4 gravity points left in fermentation.

When transferring is completed, the keg will have no pressure in it. Since the last part of fermentation will generate CO2, do you leave the keg unpressurized and let the natural CO2 pressurize the keg or do you hit it with a little CO2 to seal it and THEN let CO2 build up in the keg?

As the fermentation continues in the keg, pressure will build up. Im assuming one needs a spunding valve, right? How do you figure out where to set the spunding valve? Im assuming there's a calculator somewhere... If you know you have .83 vols of CO2 remaining in solution from fermentation and you want a total of 2.7 vols of CO2, do you use the carbonation calculators to figure out what PSI is needed to achieve the remaining vols of CO2?

Once fermentation is complete, I'm assuming you'll see the spunding valve show a drop in pressure. Once you see the drop in pressure, do you hook it up to CO2,set it to serving pressure, chill and you're done? I feel like I'm missing something here...

When spunding in the keg, I believe this is a scenario where you need to modify your dip tube, correct? How much do people typically remove? 1 inch? 2 inch?

Thanks for the help in advance!

 

[thisjrp4]

So here’s what I’ve done with success... let the beer finish fermenting or just about done. No gravity measurements necessary. Transfer to a keg and add priming sugar or DME. Purge the head space with CO2. Attach the spunding valve set to whatever pressure you need to get your volumes of CO2 at whatever temperature you are holding the keg at. Let the yeast work the sugar and carbonate the beer. After a week it will be done. Then lager in the keg and serve. It’s going to be a little yeasty and cloudy for the first bit but it eventually clears up.

 

[MrPowers]

I want to start keg spunding so I want to make sure I have it right and I have some questions.

Im pretty sure I have it down in determining WHEN to transfer to keg so FOR THE DISCUSSION, I'm going to start with assuming transfer to the keg took place with ~4 gravity points left in fermentation.

When transferring is completed, the keg will have no pressure in it. Since the last part of fermentation will generate CO2, do you leave the keg unpressurized and let the natural CO2 pressurize the keg or do you hit it with a little CO2 to seal it and THEN let CO2 build up in the keg?

As the fermentation continues in the keg, pressure will build up. Im assuming one needs a spunding valve, right? How do you figure out where to set the spunding valve? Im assuming there's a calculator somewhere... If you know you have .83 vols of CO2 remaining in solution from fermentation and you want a total of 2.7 vols of CO2, do you use the carbonation calculators to figure out what PSI is needed to achieve the remaining vols of CO2?

Once fermentation is complete, I'm assuming you'll see the spunding valve show a drop in pressure. Once you see the drop in pressure, do you hook it up to CO2,set it to serving pressure, chill and you're done? I feel like I'm missing something here...

When spunding in the keg, I believe this is a scenario where you need to modify your dip tube, correct? How much do people typically remove? 1 inch? 2 inch?

Thanks for the help in advance!

You have the basics down pretty well.

1. Transfer to keg with 3-4 gravity points remaining of fermentation. That means you need to do a fast ferment test and know where your beer is going to finish.

2. After transfer, if the keg headspace isn’t already purged using the water/sanitizer purge method, purge the headspace with inert has (CO2/n2) and add a quick burst of pressure to seat the lid (I usually do a quick blast of 20 psi). Then disconnect the gas and let pressure build up in the keg from fermentation.

3. Attach spunding valve. Set the spunding valve to the appropriate PSI for the volumes of CO2 you want based on the temperature you are spunding at.

4. if your kegs and spunding valve are pressure tight, you should not see any drop in pressure after spunding is complete. It should just stabilize at your target pressure. At that point you can remove the spunding valve, cold crash and allow the beer to condition—or tap right away as your beer will be already fully carbonated.

5. I don’t cut my dip tube. I just expect a bit more yeast out of the first few glasses. A lot of people who spund use a device called a clear beer draught system. It is basically a floating dip tube/top draw system that draws beer from the top of the keg instead of the bottom.

 

[Rob2010SS]

You have the basics down pretty well.

1. Transfer to keg with 3-4 gravity points remaining of fermentation. That means you need to do a fast ferment test and know where your beer is going to finish.

2. After transfer, if the keg headspace isn’t already purged using the water/sanitizer purge method, purge the headspace with inert has (CO2/n2) and add a quick burst of pressure to seat the lid (I usually do a quick blast of 20 psi). Then disconnect the gas and let pressure build up in the keg from fermentation.

3. Attach spunding valve. Set the spunding valve to the appropriate PSI for the volumes of CO2 you want based on the temperature you are spunding at.

4. if your kegs and spunding valve are pressure tight, you should not see any drop in pressure after spunding is complete. It should just stabilize at your target pressure. At that point you can remove the spunding valve, cold crash and allow the beer to condition—or tap right away as your beer will be already fully carbonated.

5. I don’t cut my dip tube. I just expect a bit more yeast out of the first few glasses. A lot of people who spund use a device called a clear beer draught system. It is basically a floating dip tube/top draw system that draws beer from the top of the keg instead of the bottom.

Thanks for the info.

In regards to the setting on the spunding valve, do you (A) set it for the total amount of co2 you want in the beer or do you (B) calculate the amount of co2 in the beer left from fermentation, subtract that from the total volume of co2 you want, and set your spunding valve for the difference?

 

[MrPowers]

Thanks for the info.

In regards to the setting on the spunding valve, do you (A) set it for the total amount of co2 you want in the beer or do you (B) calculate the amount of co2 in the beer left from fermentation, subtract that from the total volume of co2 you want, and set your spunding valve for the difference?

Set it for the total amount of CO2 you want left in the beer.

 

[Bassman2003]

Before I started spunding, I always had ales in the fermenter for 10-14 days. Now that I spund, the transfer takes place earlier, but the same amount of time is spend in "fermentation". So after I transfer to the keg, the keg stays are fermentation temps for a week longer. It does not have to but I like to give the yeast time to do their thing and soak up any bad stuff.

So, you have some time to watch the pressure build. What I do is close the spunding valve all the way and just check the pressure over time. Most of my ales are at 2.5 volumes of CO2 so that is roughly 25 psi @ 65 degrees. So when the pressure get a little above 25 psi I open the valve until I hear a slight hiss. Then the pressure is set to the right psi. From then on any CO2 will be released above the target and 25 psi will be maintained.

A carbonation chart is a great tool to help you find your psi setting with regards to temperature and volumes of CO2.

 

[Dland]

You've gotten decent advice above, I'll add the following variations:

I cut dip tubes about 3/4 inch, my beers usually run clear right away or after first pint. They are well cold crashed though, and cold conditioned least 4 weeks for lagers and 2 weeks for ales.

Floating dip tube sounds good too, but line might be harder to sanitize, plus if you have a lot of kegs, that is more gear.

You can spund with slower ferment, as I do with cold fermented lagers. One can tell when it is finishing by slowing of "airlock" activity. I usually do a trub dump and gravity test at this stage.

I try to leave a little more fermentable for spunding, .006 remaining above expected gravity or so. I like my beers carbed up toward 1.5 vols CO2, also allows for attenuation being a little less than expected.

You do not actually need a spunding valve if you rack with only .004-.008 gravity left to go, a daily check with gauge works too. I have spunding valves, but just saying in case anyone has a valve clog or something.

 

[whovous]

A couple more points:

It is OK to transfer with more than 3 or 4 points left so long as you know how to set your spunding valve. I think it is better to spund too soon than too late.

Make sure to adjust for temperature. I've not looked up the exact numbers, but if you want about 10psi at 40F, and are fermenting at 65F, you'll want to set your valve around 25psi or so. Sorry I am too lazy to look up and link the tables with the actual numbers, but it is important to account for it.

Oh, and leave some headroom in your keg. I found out the hard way that filling the keg to the brim just means you are going to clog your valve with krausen. A quart of headroom is probably enough if you are past high krausen.

 

[cactusgarrett]

Transfer to a keg and add priming sugar or DME.

This isn't so much spunding as it is conditioning in the keg and not worrying about how much priming sugar to use. Maybe it could be considered a hybrid method?

You could not use a spunding valve and just seal up your keg when you hit a certain gravity, but then you're really shooting in the dark with regards to what pressure you're truly getting. What would help this is doing a forced ferment test on your batch a few days into primary fermentation - that way you'll get a theoretical point at which your beer should finish at, so you know when the latest you should make the transfer and seal it up is. Provided your main fermentation goes as planned and you do hit the FG predicted by the forced ferment test, you would be good. But if something would cause you to not hit that FG your forced ferment test gave you, you'd ending up with undercarbed beer.

With regards to determining what to set the spunding valve at, check this out.
https://www.kegerators.com/carbonation-table/

 

[BruceH]

To add to the above advice: I haven't cut dip tubes, I put a slight bend on the out tube. This gets it a little higher off the trub. I still get a cloudy, yeasty first pour but that's it.