Troubles with GW Kent carbonation stone

[ManSkirtBrew]

I just bought three of these GW Kent carbonation stones. Having two problems, which I thought I'd run by you guys and gals while I'm thinking about it.

First: no gas will flow through the check valve as shipped, even up to 30PSI. The check valve has this metal sleeve around it:



It looks like the sleeve is bottoming in the housing, pinching the check valve shut. You can see here with and without the sleeve:



When I remove the sleeve, gas is able to flow, which brings me to problem #2: once the gas is flowing, most of it seems to leak out of the joint between the stone and the plastic washer. No matter how hard I tighten things down. I get some gas coming out through the stone, but the majority seems to blow right out that joint when I do a bubble test.



Suggestions are welcome!

[MikeyB]

Carb stone

Having a hard time visualizing problem #1 with the check valve from the pix, but as to #2-

I've had similar carb stones to the one shown, though not G-dub. I found that the ends of the stone were not square & smooth, rather had machining grooves and raw metal, which would not seal against the plastic end caps. The solution is to hone them smooth and flat until they seal up, using an appropriate abrasive.

Related note- don't handle the stones with your bare hands! Skin oil creates "dead" spots on the stone.

[beerdweeb]

It looks like you may be missing a gasket. That "nipple" piece should be pushed on all the way down and the metal sleeve should be pushed over the nipple and sit flush on a gasket.

[ManSkirtBrew]

There is a rubber gasket. It sits on top of the check valve (nipple), between it and the nut. At least that's how it was when I disassembled it.

[beerdweeb]

Every carb stone I've used has this sort of check valve assembly: http://www.zahmnagel.com/shop/series...ly-part-16120/

[ManSkirtBrew]

Yes, mine has the same assembly, as shown in my first post. But like I said, for some reason it doesn't let gas flow unless I remove the stainless ring. Then even when it does, gas is leaking out the ends of the stone, no matter how hard I tighten it down. So I was just hoping I was doing something wrong.

[beerdweeb]

Just to be clear (and otherwise I'm at a loss) the photo I've linked shows the assembly with a gasket yet the photo you've posted does not have a gasket. And then the second gasket fits in the female side of the union.

[ManSkirtBrew]

Ah, now I see. Thank you. There is no gasket there on mine. It might explain why gas is getting through the joint, but not why the check valve isn't working. I'll reach out to GWK and see what they have to say.

[mmussen]

I don't think this will really help you in your situation at all but I have a stone from GW as well as one from Zahm - the GW kent stone needs about 15 psi to crack open and get any bubbles flowing. My stone from Zahm needs 4 psi. I'm not sure what the difference is though.

And it does look like you're missing a gasket, when I have the tank emptied and Ive got a few I'll try to post a picture of what my check valve looks like.

[TGTimm]

In addition to the comments above, that stone looks like it badly needs to be cleaned and passivated. It has what appear to be rust spots and grunge.

The best way to clean a stone (as per Zahm & Nagel) is with an ultra-sonic cleaner. First wash should be a caustic cleaner to break down any organic materials, which will bar any acid action from reaching the minerals and rust. The second wash or soak will be an acid/passivation. Contact your chemical supplier for recommended chemicals.

The passivation soak should not need to be repeated, but the caustic cleaning, preferably with an ultra-sonic cleaner, should be done every time the fermenter/bright is cleaned.

An alternative to the US cleaner, 'though less effective, is to use a pump to back-flow the cleaners through the stone, in the direction the CO2 would flow.

Once the stone is perfectly clean, the wetting pressure should be significantly reduced.

[ManSkirtBrew]

Thanks Timm. The stone was wet before I had a chance to passivate it, so this is what I got. You know how things go around the brewhouse sometimes. I'll be giving them all a thorough ultrasonic cleaning and passivation before pressing them into service.

[ManSkirtBrew]

Well, there's your problem. The slit in the check valve goes through the side of the damn valve instead of through the bottom where the gas comes through.