Hammering in beer lines with Cornie-Check Valve-Beer Engine

[Jim]

The title says it.

I have the cornie gassed up, then about 4' of beer line from the disconnect to the check valve which is connected by about 1/2" of beer line to the bottom of the beer engine.

When I tested it with plain water, it hammered for a few pulls then settled down. Now that it's been on pressure test for a week or so, the water in the keg is fizzy, it won't stop hammering. There's also turbulence in the output from the check valve. I've tried reducing the pressure as low as 5psi, with no improvement.

I suspect an airlock, but I can't see it because the pipe's the blue plastic kind, not the transparent type. However, even if there was an airlock, I would have thought it would come out (I've moved the line around so that any air would move towards the beer engine).

Any suggestions for a solution from someone using this kind of set up.

[Jim]

Try increasing the pressure in thhe keg or leaving it vented, it sounds like you might be pulling a vacuum.

Nope, the pressure in the keg started at 20psi or so and I gradually reduced it. After my post I reduced it to next to nothing and the hammering stopped. It was still turbulent in the BE pipe, though.

I feel I might have overdone the carbonation - it's been sitting at 15 - 30psi for about a week at 10C, so it's quite gassy. I'll let it settle a while and pressure up again and see what happens.

I've got my tap now, so I can use that instead for the brew that's ready to go in the cornie, but I need to make a mounting bracket for it first.

I have to get the bugs out before I risk beer!

[Jim]

It could well be the high level of carbonation and low pressure in the piston chamber may be causing the co2 to break out.

I think that was it. I left it a while (an hour maybe) unpressurised, then gassed it back up. The hammering has virtually stopped - though anything above about 5psi starts it again.

I always though check valves would cope with more pressure than that, but obviously not!

[oxford brewer]

I thought a check valve just stopped any flow back to the corni?

[delboy]

I have a similar setup to yourself jim (cornie to beer engine) i like my beers on the fizzy side and i can't be arsed dropping the pressure each time i want to serve. I used to get a lot of 'hammering' (i think we are talking about the same thing, vibration in the check valve etc?).

Actually after reading one of your posts i realised having the distance between the check valve and the beer engine as short as possible would reduce the breaking out of CO2 (quite a lot).
The other thing i did was to securely fasten the check valve (screwed it onto the bench the beer engine is on) this also made a difference to how the system behaved.

With just these two tweaks i can have my beer gassed up pretty good but still get a decent pour.

Maybe worth trying?

[Jim]

I have a similar setup to yourself jim (cornie to beer engine) i like my beers on the fizzy side and i can't be arsed dropping the pressure each time i want to serve. I used to get a lot of 'hammering' (i think we are talking about the same thing, vibration in the check valve etc?).

Actually after reading one of your posts i realised having the distance between the check valve and the beer engine as short as possible would reduce the breaking out of CO2 (quite a lot).
The other thing i did was to securely fasten the check valve (screwed it onto the bench the beer engine is on) this also made a difference to how the system behaved.

With just these two tweaks i can have my beer gassed up pretty good but still get a decent pour.

Maybe worth trying?

Thanks for that, DB. I couldn't get the check valve any close to the beer engine, the pipe is only about 1/2" long, but it isn't held down - just hanging off the bottom of the BE cylinder. And yeah, it sounds the same - a juddering of the whole beer line as I pull the handle on the beer engine accompanied by a loud banging noise. It can't be doing the BE any good, and it would probably stir up any yeast in the cornie if I had beer in there.

I might try somehow fixing the check valve to the drip tray bracket to secure it, but to fasten it anywhere else would mean lengthening the line.

[Jim]

Just to clarify exactly what it's doing (and it's doing it even at 5psi, though not as badly.

Video

[delboy]

Yeah thats the same as i was getting, i stressed in my post that keeping the run between the check valve and the BE was crucial but TBH i think securing the check valve itself is more important.
My own one is secured to the underneath of the bench the BE is on and its probably got a run of 10 inches i would have thought (i orginally had it a few feet long ). Since securing the check valve properly the system plays up a lot less.
Last night i was drinking pints of my wit from it with no problems what so all, when i killed the keg i moved it over to a keg of dunkelweizen which did judder a bit but a short pull on the PRV and on the second pint it was all ready settling down nicely.

BTW i gas my kegs up and then leave them, ie i don't have gas on them at a constant dispense pressure or anything as fancy as that, if i think they need more gas i just give them an extra blast.

[Jim]

I don't think it's pulling a vaccuum - you get a totally different feel on the handle when that happens.

I've mounted my tap now as well [insert your own joke here] , and I get hammer on that when I turn the flow off!

Maybe I need some different beer line - the stuff Norm supplied seems to have very little give in it, and that's possibly the trouble.

[Aleman]

This is one of the problems with using a corny and a beer engine, (compared to a cask) and that is the amount of restriction imposed by the narrow diameter dip tube and the poppets. I have a modified corny I use for the beer engine which has had the poppet removed from the post . . . You can just about force a 1/2" line over the post., and it seals well with a O clip. . . . another solution is to remove the post and fit the 1/2" line direct to the mounting post . . . do it to the gas in post, after removing the gas in dip tube, and lie it down with the gas in lowest and you have a horizontal cask

I keep my lines as short as possible . . . The CV is connected to the inlet of the BE by a 2" length of reinforced PVC . . . and just dangles there not connected to anything and I get no hammering in the system

[Jim]

The gas/air in the clear pipe is coming from somewhere. As the suction comes from the bottom of the keg (ie it's totally submersed under water) it's either letting in air somewhere or pulling a vac causing the co2 to gas off.

You could have a pin hole in the dip tube (i've seen that reported 2 or 3 times here), the dip tube o-rings may be knackered, the pipework is letting in air somewhere or you may just need to tighten the posts. You can virtually eliminate a vac by removing the check valve and pulling the water through with the prv open, if it stops it was either pulling a vacuum or there was an air leak somewhere around the check valve.

I think the air is just CO2 coming out of solution - the pump is creating a vaccuum (as pumps do!) and as the water/beer comes through the check valve it sees a sudden drop in pressure. If there were any leaks the beer would be p*ssing out of them.

I've got beer in the cornie now and it's connected to the lever tap - no problem there with turbulence at all, though I was expecting some foaming having read other people's experiences. Maybe it was a bit cold at 10C - I've raised it to 12C as I could barely taste the malt in the beer.

I filled the cornie from the placcy barrel using a tube from tap to the cornie liquid disconnect, so everything was closed (and the cornie was full of CO2). I reckon I lost so carbonation, though, cos it's quite flat out of the tap (i.e. very little head). Tastes OK, though, considering it's still quite young.

[Jim]

This is one of the problems with using a corny and a beer engine, (compared to a cask) and that is the amount of restriction imposed by the narrow diameter dip tube and the poppets. I have a modified corny I use for the beer engine which has had the poppet removed from the post . . . You can just about force a 1/2" line over the post., and it seals well with a O clip. . . . another solution is to remove the post and fit the 1/2" line direct to the mounting post . . . do it to the gas in post, after removing the gas in dip tube, and lie it down with the gas in lowest and you have a horizontal cask

I keep my lines as short as possible . . . The CV is connected to the inlet of the BE by a 2" length of reinforced PVC . . . and just dangles there not connected to anything and I get no hammering in the system

That seems a reasonable explanation, but why does the restriction cause juddering in the pipe rather than just making it harder to pull the beer through? And even then, why does the gas pressure pushing the beer out not overcome the restriction?

The way this system is behaving baffles me!

[Jim]

why does the gas pressure pushing the beer out not overcome the restriction?

A Beer Engine is a high flow bit of kit compared to the usual (designed) flow rates from a cornie. Maybe vacuum wasn't the best description on my part, a better description would be that the beer engine is creating too great a pressure differential such that the gas in the keg can't shift the beer up the dip tube without co2 breaking out due to the low pressure. There will probably be a maximum level of carbonation that the system can cope with somewhere between what you had and what you have now.

Alemans description and solution makes perfect sense IMO ie it's the restriction that causes the pressure differential to be too great, in the same way that a meter or so of 3/16" beer line will reduce the pressure at the tap end when serving with a regular tap. A modified keg would be the ideal solution if a little impractical.

I hear what you're saying, but the flow rate from the lever tap is far higher than you could pull a pint using the beer engine. I can fill a glass with beer in about 5 seconds with no foaming so there can't be that much restriction. Maybe it's the low carbonation of the beer compared with the force-carbonated water I was pulling through the BE? Maybe I should try the BE with the actual beer and see how it copes.

[delboy]

This is one of the problems with using a corny and a beer engine, (compared to a cask) and that is the amount of restriction imposed by the narrow diameter dip tube and the poppets. I have a modified corny I use for the beer engine which has had the poppet removed from the post . . . You can just about force a 1/2" line over the post., and it seals well with a O clip

Interesting aleman, might look into doing something like that as i have some juddering (not as bad as jims though) although this method would require me to have a dedicated BE cornie and i wouldn't be able to hop about the kegs as i do now.

[Jim]

..I disagree, it takes about 20-30 seconds, possibly more to pour a pint with a 'dalex/lager' type tap..

Well there must be something wrong with mine then! If I pull the tap handle forwards (fully open) the beer shoots into the glass at a rate of knotts, and fills the glass in a few seconds - I did it 3 times last night. The carbonation level in the beer is quite low at the moment.