GW Kent carb stone

[wailingguitar]

I have one of these in a 30bbl tank:

http://www.gwkent.com/micro-oxygenation-carbonation-stone-assembly-12in-stone.html

When I tried to carb the beer, I had little to no results. Basically between about 11am and 6pm yesterday I ran gas in slowly... I determined previously that the wetting pressure on this stone was about 16 psi, I had regulator set between 18 and 20... I was looking for 10psi in the beer (according to Zahm reading). Tank reached 10psi and I took a reading, Zahm showed 2psi. I bled pressure down and let gas flow in again over a couple hours until gauge read 10psi, did Zahm and it had barely moved. Bled pressure again and had someone turn off gas at 10psi. Checked it this morning and Zahm was only reading 3psi. I checked another tank to be sure Zahm was not at fault and got 10psi, so is not Zahm.

I then turned gas back on and put my ear up to the tank, it sounded like large bubbles moving through the beer. I am thinking at this point that the fittings on the stone may have come loose allowing CO2 to bleed out around the stone rather than through the diffuser. I have never had this happen before, any thoughts would be helpful.

[mmussen]

A few thoughts for for.
When you carbonate you need to add the wetting pressure to the total pressure you want in the tank. So if you want the tank to be reading 10 psi when carbonated and the wetting pressure is 16 (which is quite high for a stone) you should be setting your regulator at about 26 psi. Also I put top pressure on my tank before running gas through the stone to keep the bubbles small - if the pressure differential between the gas in the stone and the tank is too high you'll get large bubbles no matter what.
You may be having leaking around one of the gaskets or fittings of the stone - I check mine in water before installing into a tank every single time.
There are several very good threads on carbonating here in the forums - I'd recommend taking a look at them.

Cheers and good luck

[wailingguitar]

A few thoughts for for.
When you carbonate you need to add the wetting pressure to the total pressure you want in the tank. So if you want the tank to be reading 10 psi when carbonated and the wetting pressure is 16 (which is quite high for a stone) you should be setting your regulator at about 26 psi. Also I put top pressure on my tank before running gas through the stone to keep the bubbles small - if the pressure differential between the gas in the stone and the tank is too high you'll get large bubbles no matter what.
You may be having leaking around one of the gaskets or fittings of the stone - I check mine in water before installing into a tank every single time.
There are several very good threads on carbonating here in the forums - I'd recommend taking a look at them.

Cheers and good luck

Thanks for your input, it is appreciated. I see what you're saying, but my experience here has been that the way I have been doing it works very well. For instance, in my 20bbl tanks, starting from only having a couple pounds of head pressure, I will set the regulator to 10psi at first and then slowly ramp up to about 14 as the tank approaches about 8psi head pressure. When it hits 10, I will do a Zahm and usually see about 7psi in the Zahm, bleed pressure back to that point and continue in flow. Check again when head pressure reaches 10 and 99% of the time the Zahm agrees. I can easily do a 20bbl tank over the course of a 5 to 6 hour day with very little CO2 loss. My procedure for my 10bbls is pretty much the same, however the stones I have in the 30bbls are different and I have generally been seeing a disproportionally long time to carb, but I have done it about a dozen times in my 30s which is enough to establish that it has been working... this occasion today is an anomaly and I am trying to figure out why.

[BMan1113VR]

I've used similar stones to that one, and none of them have even had close to a 16psi wetting pressure (4 is more average). So it definitely sounds like you have a problem of some sort. A thought: those stones usually have check valves in them...are you sure that it is oriented the correct way?

[wailingguitar]

I've used similar stones to that one, and none of them have even had close to a 16psi wetting pressure (4 is more average). So it definitely sounds like you have a problem of some sort. A thought: those stones usually have check valves in them...are you sure that it is oriented the correct way?

Yep, I have two of them and they both behave the same way. Wacky, eh?

[fuelforthehate]

Does your checkvalve have a small stainless ring around the base of it to secure it to the barb? I have 4 GW Kent carb stones and, while the first operated fine with the stainless ring on, the subsequent three all needed that ring to be removed in order to get ANY flow at all. I've had no issues operating the stones without it.

[MadHatter]

Yep, I have two of them and they both behave the same way. Wacky, eh?

I have the identical carb stone on a 3.5 bbl system and can confirm that the wetting pressure is 15-16 PSI. I carbonate in two stages. Stage 1 is 21 PSI for 5 hours or so, until I reach 8-10 PSI in the head. I then bump up to 25 PSI for another 2 hours or so until had reads 13ish. I then condition the sealed tank for a day, and haven't encountered any issues with low carbonation.

I clean and check my stone every batch for performance, and disassemble entirely every 10 batches to make sure it's all good.

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