Spunding Tips

Discussion in 'Homebrewing' started by thebriansmaude, May 8, 2018.

  1. thebriansmaude

    thebriansmaude Initiate (68) Dec 16, 2016 Alberta (Canada)

    Hey all, about to attempt my first keg carbonation via spunding. I have built myself the typical spunding valve with controlled pressure release valve, gauge and gas QD. Pardon my severe noobism in this area:

    1. How many remaining SG units are typical before transferring to serving / spunding keg from fermenter? Is a forced fermentation test totally necessary to accomplish this or can you aim high ? how high is too high?

    2. As I let the beer finish fermentation in the serving vessel it will be at ale fermentation temperature. How do I set the PRV so that the level of carbonation will be appropriate at serving temperature? I'm thinking PV = nRt type stuff here.. Just use a carbonation chart for the warm ale temps and then throw it in the keezer and voila ??

    3. Any other tips ? I am boldly attempting this on a keg dry hopped west coast IPA - I am dry hopping commando in the keg and using a floating dip tube to serve. What could possibly go wrong ? :wink:

    TIA !
  2. VikeMan

    VikeMan Meyvn (1,470) Jul 12, 2009 Pennsylvania

    Yes, use the carbonation chart for the desired volumes of CO2 at the temperature at which you're spunding. When you later chill the (sealed) keg, the pressure will go down to the chart's PSI matching that same volumes of CO2, but at the lower temperature.

    IOW, Volumes of CO2 in a sealed container are not temperature dependent, but pressure is.
    thebriansmaude likes this.
  3. thebriansmaude

    thebriansmaude Initiate (68) Dec 16, 2016 Alberta (Canada)

    @VikeMan , thanks. One more question - say I want to set the spunding valve to 30 psi - my plan was to pressurize an empty keg to 30 psi, attach the spunding valve, and then dial in the prv to the point it starts to release, then dial back a touch, just to make sure it’s accurate.

    After I transfer the beer with say 0.004 sg remaining or there abouts, throw on the spunding valve and forget about it. Am I correct to assume that after the beer is done fermenting, it should be sitting at my desired carbonation level? Sound right?
  4. VikeMan

    VikeMan Meyvn (1,470) Jul 12, 2009 Pennsylvania

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  5. thebriansmaude

    thebriansmaude Initiate (68) Dec 16, 2016 Alberta (Canada)

    One more question about this:

    With the keg full of still fermenting beer, should I worry about krausen getting into the spunding valve ? In this instance I probably transferred too late and wont get much more fermentation, but if I had 4-6 points to go could this be an issue?

  6. Prep8611

    Prep8611 Aspirant (250) Aug 22, 2014 New Jersey

    This has happened to me once. Yes it can happen, It will literally come out of the pressure relief valve. I took apart the valve and sanitized all the pieces and reput it all back together. No worse for wear.
  7. pweis909

    pweis909 Poo-Bah (1,756) Aug 13, 2005 Wisconsin

    What approach do spunders take to know that their fermentation has .004 gravity units to go (or whatever)?

    It seems that you either really need to know your fermentation in ways that I have never managed to achieve - namely knowing your terminal gravity very well and knowing how long it takes to get to .004 units above it.

    Do.you just err on the high side, or do you really know your fermentation this well?
    chavinparty likes this.
  8. wasatchback

    wasatchback Aspirant (271) Jan 12, 2014 Utah

    You can do a Forced Ferment Test, although I’ve had a couple of those end up slightly lower (.001). Just pull some beer on day 2 and put it on a stir plate at room temp (or higher) for a few days and measure FG.

    Or brew the exact same beer over and over.

    You shouldn’t have issues with krausen clogging things in the keg if you’ve only got .04 to go (which should be all you need for carbonation). If you’re worried about it just put the spunding valve on the end of a foot or two of tubing.
    thebriansmaude likes this.
  9. minderbender

    minderbender Initiate (187) Jan 18, 2009 New York

    Yeah you could probably get within .001 or .002 with this method, if you could track the gravity of your fermentation with precision. But how do you do that? Especially if you're fermenting in a bucket or carboy or something where checking the gravity means letting oxygen in.
  10. wasatchback

    wasatchback Aspirant (271) Jan 12, 2014 Utah

    If you’re checking when fermentation is winding down you still have some Co2 production which I would think would mitigate the small amount of O2 you’re letting in. If you use a particular yeast enough I’m sure it’s relatively easy to tell where you’re within a certain peramater along the way. I sometimes ferment in Carboys but mostly in Conicals with sampling valves.
  11. minderbender

    minderbender Initiate (187) Jan 18, 2009 New York

    Certainly a sampling valve helps. It just feels like catching a falling knife to me, but maybe I'm exaggerating the difficulty.
  12. GreenKrusty101

    GreenKrusty101 Crusader (730) Dec 4, 2008 Nevada

    Let me go out on a limb here...one can make an educated guess based on experience and airlock activity :astonished:...or just forget the spund if time it takes to force carb is not out of the question, imho.
  13. Supergenious

    Supergenious Disciple (343) May 9, 2011 Michigan

    Does it really matter if you rack to keg with .004 or say .008 left to FG? If your spunding valve is set to the proper pressure it shouldn’t over carbonate. Probably best to stay on the side of caution, and best to rack too soon than too late. Is this correct?
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  14. Prep8611

    Prep8611 Aspirant (250) Aug 22, 2014 New Jersey

    No it won’t pvercarbonate but it could make a mess.
  15. wasatchback

    wasatchback Aspirant (271) Jan 12, 2014 Utah

    If a few points less to go means less yeast carried over into the keg I think that’s a good thing. I’d rather undershoot and have to blow off less aroma and adjust with some additional CO2.

    I would almost bet with all the talk of Hop creep you could probably reach FG, transfer into a keg with hops and the refermentation created by the sugars/enzymes in the hops might create enough CO2 to carbonate.
    #15 wasatchback, May 18, 2018
    Last edited: May 18, 2018
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  16. MorningDew72

    MorningDew72 Initiate (44) Aug 15, 2014 Washington

    I guess it just depends on how much you fill in the keg. Even if there were 10 points left most of the vigorous activity should be done. Fermentation under pressure reduces the krausen when compared to a vented fermentation. But then again hops can really agitate CO2 in beer and cause a mess in the case of dry hopping in the keg. When in doubt I guess just leave a couple of inches head space in the keg?

    I think getting to know your yeast is the most important thing with spunding or capping in regards to when to transfer in the case of the corny keg/spunding valve method, if you are looking to do it at exactly x points left. Fermentations with pure cultures can be very predictable if you brew similar wort and have controlled fermentation and similar pitching rates, etc.

    I guess more of the whirlpool/initial dry hop (if done) would be vented through the airlock but less of the keg hop (if done) would be vented through the spunding valve. I think most yeast will be carried out in the first few pours anyways once it's been conditioning cold for a few days. I spunded a couple of lagers recently and it was still pretty hazy when I racked, around 4 points left (luck), and came out crystal clear after a couple of weeks of lagering at freezing temp and getting through the first few pints. Looked filtered. There was the typical tiny bit of yeast sludge at the bottom after it kicked but nothing more than if I cold crashed a beer in the fermenter then racked into a keg.
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  17. Rrrainy

    Rrrainy Initiate (0) Jan 5, 2018 Netherlands

    To come back to this topic. I've just done my first spunding experiment where I transfered the beer at 1.026 from the fermenter into the keg which was filled with a 5oz of whole leaf hops. The final gravity turned out to be 1.018 and I had set the spending valve to 40psi (read this somewhere as a recommendation).
    Then with cold crashing ,the pressure reduced to something like 30psi and left it for a week like that. Then I vented some of the pressure to 15psi. The problem I have now is that I only get foam out of the keg.
    Did I just overcarbonate my beer or is there something specific about using whole leaf hops that could cause this foaming?
    Is there a way to solve it, like venting some pressure every few days as the overload of CO2 comes out of the beer/foam now that it's at 15psi?
  18. thebriansmaude

    thebriansmaude Initiate (68) Dec 16, 2016 Alberta (Canada)

    @Rrrainy - I set my pressure based of of a CO2 volume chart - if I recall, about 30psi will get you 2.5 volumes at ~68*, at ~37* the pressure should drop to about 12psi, which is where you want to be for 2.5 vol CO2. Looks like 40psi was a bit high.

    Luckily with a spunding valve you can fix an overcarbonated keg ! If I am not mistaken (i'm no expert here) you can just set your pressure relief valve to desired pressure for the carbonation level you want and it should bleed the keg until that pressure is reached.
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  19. Rrrainy

    Rrrainy Initiate (0) Jan 5, 2018 Netherlands

    Thanks for the advice. Indeed using the pressure relief valve should be perfect for releasing the pressure building up from the overload of dissolved CO2, now being slowly released at the lower pressure that I now have in the keg.

    I'm still wondering though what caused the foam to form. As far as I remember I had foam already coming out of the tap (with throtling valve) when it was still at 30psi and I didn't relieve the pressure.
    Also when I opened up the keg yesterday, it was all foam slowly coming out of the top pushing a lot of the whole cone hops out. At this time I had already relieved the pressure multiple times, so the head pressure stabilized at about 15psi (I like my NEIPAs a bit higher carbonated).

    At this point, is my best option just waiting for the foam to settle in the keg?

    To provide some context, this was the first time spunding for me and I did an experiment with one keg filled with dry hops to which I transfered the still fermenting beer and then put the spunding valve on and another keg that was filled after the beer had completely fermented out. Mainly to see what the effect was of spunding on taking out the last bits of oxygen in a keg and to assess my current transfering process ( pushing out sanitizer out of the keg with CO2, drop in dry hops, flush mutliple times at 30psi, closed transfer of beer, flush head space multiple times at 30PSI, then relieve pressure to 10PSI).

    The beers at the moment taste and look quite different though. Don't know if that's because of the oxgen, the possible biotransformation in the spunding keg or the fact that most likely a lot of the whole leaf hops were pushed to the top in the spunding keg (even though I flipped the keg once for a few hours to make sure the hops sink in the beer). The spunding keg beer also looks a lot clearer and paler than the other one. The beer was fermented with wlp007.

    I'm planning to use spunding consistently now when making NEIPAS, mainly to consume the oxygen that's still in my serving keg after doing the closed transfer.
    Pellets do seem to be the easier option though, as dropping 5oz of whole leaf hops into a 2.5 gallon keg is a mess and it took so much time to get it all in there that so much oxygen came in forcing me the flush the empty keg again with 13 times at 30psi.

    And indeed, maybe it makes more sense to transfer the beer a bit later so that not a lot of the aroma is vented.