Pressure not increasing as corny keg warms

Discussion in 'Homebrewing' started by mijclarke, Apr 5, 2022.

  1. mijclarke

    mijclarke Initiate (63) May 4, 2014 Illinois

    On day 14 I placed corny keg in fridge with 3 psi of CO2 in case there was suck bag. After 24 hours i removed from fridge, placed in basement, unhooked CO2 and popped on spunding valve. It had a pressure of 4 or 5 psi. I released some air and got it to 2 or 3 psi and then tried tightening the spunding valve completely closed. Went to check again and was surprised that after a few hours the pressure was down to 0. I assumed the pressure would increase as the keg warmed. Not trusting my spunding valve (maybe it was leaking) I took it off, popped on the CO2 and did a gentle purge and filled it with 3 psi for a min and then disconnected. I took a wrench to make sure my posts were tight and then went to bed. Will be dropping magnet with dry hop bag later today and going to pop the spunding valve on again to see what the pressure is doing. Any thought on pressure not going up as the temp rises? Basement temp is around 63 and fridge temp was around 37
     
  2. jbakajust1

    jbakajust1 Crusader (774) Aug 25, 2009 Oregon

    So, 3 psi isn't much. I would expect that the lid isn't seated correctly if you only used 3 psi. Usually takes 30 psi to fully seat a lid.
     
    riptorn likes this.
  3. riptorn

    riptorn Zealot (528) Apr 26, 2018 North Carolina
    Society Trader

    Posts and other connections with o-rings or gaskets can sometimes be torqued too much; squeezing, squishing and deforming them to a point they don't make a good seal.
    Have you checked the connections and lid for leaks? If not, spray some Starsan on all connections and around the lid, watching for bubbles.
    Leaks aren't usually too difficult to locate but can sometimes be a challenge to stop. More oomph isn't always the remedy.
     
  4. riptorn

    riptorn Zealot (528) Apr 26, 2018 North Carolina
    Society Trader

    To follow up on what @jbakajust1 said about seating the lid, you don't need to keep 30 psi on it for hours or even minutes. A few seconds should be enough to seat the lid, then bleed off the excess pressure via your PRV (if equipped) or the spunding valve, or by depressing the gas post poppet.

    ETA: This has worked for me.
    Unlock the lid as if you were going to remove the lid, but don't remove it. Drop it just a tad then pull up firmly as if you were going to close it up and put the CO2 to it. As pressure increases, lock the lid. I'd do that in case the gasket somehow got cattywhompus around the lid.
     
    #4 riptorn, Apr 5, 2022
    Last edited: Apr 5, 2022
  5. billandsuz

    billandsuz Zealot (500) Sep 1, 2004 New York

    The accuracy of your pressure gauge is questionable. They all are. Below around 8 or 9 psi things get wonky. At 3 psi it's a ral crap shoot. It's a $5 piece of equipment after all.
    I would not sweat it too much.

    Cheers
     
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  6. VikeMan

    VikeMan Poo-Bah (2,005) Jul 12, 2009 Pennsylvania
    Society

    A day at 3 PSI isn't going to get much CO2 dissolved, and it's nowhere near equilibrium yet, so once you remove the gas, the headspace CO2 will mostly go into solution, bringing your headspace pressure down to at/near 0 gauge.

    That's not to say that you might not also have a leak, but a leak isn't required to cause what you're seeing.
     
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  7. mijclarke

    mijclarke Initiate (63) May 4, 2014 Illinois

    Tried beer last Sunday and it was quite good. I kept it on ice and once guests left I immediately placed in cold fridge but didn’t put any gas on it. May try and hold on to some till April 29th. I’m guessing the corny keg is 1/3 full. Should I put a couple PSI on it now and increase a little before the 29th? Carbonation was on point last Sunday and but I’m assuming it has inevitably gone down since I didn’t hook up the gas
     
  8. VikeMan

    VikeMan Poo-Bah (2,005) Jul 12, 2009 Pennsylvania
    Society

    If you are saying you were dispensing beer without the keg being on gas, then yes, the CO2 level in the beer will go (already has gone) down, because it seeks a new equilibrium between the now smaller liquid volume and larger headspace volume.

    If you are saying that you were dispensing beer with the keg being on gas, and if the PSI at the time was appropriate to maintain the CO2 volumes at the beer's temperature, then you could take it off the gas afterwards, and assuming no leaks, your CO2 volumes in the beer will not have changed.

    But in general, the best way to keep your beer at the carbonation level you want is to put it on gas at the PSI required to reach and maintain your target CO2 volumes at the beers temperature, and just keep it there. i.e. don't screw around with fluctuating temperatures and/or turning the gas on and off. There are lots of charts online to tell you what that PSI would be.
     
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  9. mijclarke

    mijclarke Initiate (63) May 4, 2014 Illinois

    I should have clarified that I had very low gas on 1-2 PSI during my tasting and then took it off so hopefully no leaks and it’s still has most of its carbonation still. Thanks