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what's happening here? physics question?


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#1 positiveContact

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Posted 16 December 2022 - 02:06 PM

I have a keg that I'm dry hopping using a SS hop screen like this:  https://www.morebeer...zBoCFdoQAvD_BwE

 

35715.png

 

you can't see in this picture but there are small holes in the lid.

 

anyway while I was filling the keg I heard the hop screen seemingly sliding up or down in the keg (metal on metal scraping sound).  I didn't think too much of that but just now I poured some beer and I heard it slowly sliding up or down again.  is it possible that the pressure in the headspace can change the buoyancy situation in there and this thing is right on the edge of floating/sinking?


Edited by postSingularityHumanoid, 16 December 2022 - 02:07 PM.


#2 Stout_fan

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Posted 31 December 2022 - 09:13 AM

Well, hops do entrap air. The place I almost went to work at had a new brew kettle with hop cannons. They purge them with CO2 and then shoot the charge into the kettle. So I'm guessing it's just a neutral buoyancy thing. You can always slap a couple of sanitized marbles in there to keep it weighted down if you wish. I have the exact same thing and I never really worry about it.



#3 positiveContact

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Posted 31 December 2022 - 10:56 AM

Well, hops do entrap air. The place I almost went to work at had a new brew kettle with hop cannons. They purge them with CO2 and then shoot the charge into the kettle. So I'm guessing it's just a neutral buoyancy thing. You can always slap a couple of sanitized marbles in there to keep it weighted down if you wish. I have the exact same thing and I never really worry about it.

 

I guess I figured pellets didn't hold much.  surprising they can move that much mass (the SS hop tube) around.



#4 denny

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Posted 03 January 2023 - 12:21 PM

I guess I figured pellets didn't hold much.  surprising they can move that much mass (the SS hop tube) around.

I think you're correct.  I'll try to check with my sources.



#5 MyaCullen

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Posted 08 January 2023 - 11:01 AM

I wonder if the co2 coming out of solution is lifting the hop pellet particles?



#6 denny

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Posted 08 January 2023 - 02:20 PM

I wonder if the co2 coming out of solution is lifting the hop pellet particles?

I think you're on the right track.  Pellets are providing nucleation sites for dissolved CO2.



#7 positiveContact

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Posted 08 January 2023 - 02:55 PM

I wonder if the co2 coming out of solution is lifting the hop pellet particles?

 

I guess I'm surprised there was enough little bubbles of CO2 stuck to the hops to lift that SS hop screen.  it's actually got a little heft to it.



#8 Stout_fan

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Posted 08 January 2023 - 08:02 PM

I think you're on the right track.  Pellets are providing nucleation sites for dissolved CO2.

I think you got it guys!




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