Wetting Pressure of “Carbonation” Stone and Flow Rate of Oxygen Flow Meter

[Brewmegoodbeer]

The wetting pressure of a carbonation stone is the PSI required for gas to come through the very small pores of the stone. This number is usually added to the PSI that you can want to carbonate your beer to. Oxygen flow meters such as the one blichmann offers has a dial at the end of the meter where one sets the flow rate (1 liter/min as an example). Has anyone found that wetting pressure correlates with the allowance of oxygen to even flow through the stone? For example: if one were to dial the flow meter back to 0.2 l/min would gas even flow out as wetting pressure is impeding this? If its 0.4 l/min setting that counteracts the wetting pressure should this be added to what you dial your flow rate to? Example: if i choose to want 1l/min flow I know dial my flow meter to 1.4 L/min to account wetting pressure?

 

[mongoose33]

What you've described above is my understanding of wetting pressure.

 

[Brewmegoodbeer]

What you've described above is my understanding of wetting pressure.

Thank you! I just wanted to confirm my thinking process on this. Just bought an oxygen tank from a local welder and grasping the idea of oxygen flow rate into wort. Ill have to test my carb stone to see what dialed rate allows oxygen to flow through the stone. Cheers!

 

[MaxStout]

I have found that I need at least a couple PSI gauge pressure before I notice O2 emanating from the stone. This could be a combination of the wetting pressure and the pressure needed to overcome the fluid pressure of the wort at the bottom of my fermenter. I don't have a flow meter, only the regulator and gauges, and I adjust O2 pressure just enough to aerate without a lot of bubbles rising to the surface and being wasted.

 

[Robert65]

I'm not sure it's really relevant in practice anyway. You don't really want to just set an arbitrary flow rate. You want to find a flow rate that gives a minimal flow, such that bubbles just barely -- or actually not quite -- reach the surface, which will vary with your wort depth and density. Any more flow, and oxygen reaching the surface is (obviously) not being dissolved into the wort but just dispersing into the atmosphere. You'll want to just dial up the flow until you hit this limit, ignoring any readings on a meter. At that point, you can determine empirically how long to run the O2 to obtain good results in fermentation.

 

[Brewmegoodbeer]

I have found that I need at least a couple PSI gauge pressure before I notice O2 emanating from the stone. This could be a combination of the wetting pressure and the pressure needed to overcome the fluid pressure of the wort at the bottom of my fermenter. I don't have a flow meter, only the regulator and gauges, and I adjust O2 pressure just enough to aerate without a lot of bubbles rising to the surface and being wasted.

Wasted you say?? Every now and then, I don’t mind being a wee bit wasted myself,

 

[Brewmegoodbeer]

Wasted you say?? Every now and then, I don’t mind being a wee bit wasted myself,

Thanks for the insight. Ill be looking into the pressure/flow rate it takes to pump oxygen through my stone. Ive always been a “splashing my wort into my conical” guy but enough research has influenced me that pure oxygen really makes a difference.

 

[Brewmegoodbeer]

Thanks for the insight. Ill be looking into the pressure/flow rate it takes to pump oxygen through my stone. Ive always been a “splashing my wort into my conical” guy but enough research has influenced me that pure oxygen really makes a difference.

Meant to reply to robert65 btw

 

[Vale71]

If you're using an actual flow regulator you don't need to take the wetting pressure and other losses into account as the flow regulator will compensate for those automatically so as to actually give you the flow rate you've set it for.
If you're using a flow meter then what you read on the scale is the actual flow through the stone, so again you don't need to consciously compensate for any flow restriction, you just increase pressure until the flow reading matches your target flow rate.