Controlling foam on flash coolers or jockey boxes.

[javert]

I used a keg flash cooler last weekend, and got plenty of foam most of the evening. Ice actually formed in the water cooling the coils, and there was an impeller and a pump circulating water through the line up to the tower, so I don’t think it’s an issue about the lines not being cold enough.

The kegs of beer had been properly carbonated at 15 psi at about 2 °C; however, they weren’t stored in a cold place while serving since one of the flash cooler’s advertising points was the ability to serve cold beer even if warm on the kegs. Although serving pressure was set at about 10 psi (which poured beer slowly), I suspect pressure built up on the kegs as they got warm, so actual pressure on the lines could have raised. Since the beers were on pin lock kegs without a manual pressure relief valve, I couldn’t relieve the building pressure. At night, beer foam came controlled, so it’s likely that the kegs lost a significant part of their initial pressure by then.

I’m treating here flash coolers and jockeyboxes the same here since the principle of operation is similar. Are any of those really designed to serve beer that it’s both warm and fully carbonated before? How can you control the foam in them beyond keeping the lines cool?

 

[IslandLizard]

I don't know anything about flash coolers, but it looks you've answered your own questions already.

The warmish keg and the resulting higher pressure inside is the culprit. It's all about the balance between temperature, CO2 pressure, and resistance (back pressure) in the dispensing system. When CO2 is allowed to come out of solution, you get foam, and under-carbonated beer.

The flash cooler may chill the beer on it's way to the faucet, but can't put CO2 back into solution that quickly, me thinks.

Since the beers were on pin lock kegs without a manual pressure relief valve, I couldn’t relieve the building pressure.

Of course you can release the pressure in a pin lock keg...
Push an open Quick Disconnect on the gas post, or just push the poppet down with a small screwdriver, the point of a key, etc.

 

[Vale71]

Since the beers were on pin lock kegs without a manual pressure relief valve, I couldn’t relieve the building pressure. At night, beer foam came controlled, so it’s likely that the kegs lost a significant part of their initial pressure by then.

Seems like you are confusing the concepts of headspace pressure and carbonation. Of course you can relieve headspace pressure (even if your kegs are not fitted with a PRV as pointed out by the lizard) but that is not going to instantly reduce your beer's CO2 content. As a matter of fact, if the keg is at ambient temp it will certainly have an equilibrium pressure that is higher than just 10PSI. If you reduce the pressure in the keg your beer will become unstable and foaming is what you will certainly get.
Long story short when using a flash cooler to serve from a small keg you actually need to set the regulator to a much higher pressure to avoid issues with foaming, doing the opposite will set you up for disaster.

 

[sicktght311]

Yeah i was going to add as above, when using any flash cooling or jockey box serving vessels with cooling coils, you need to set your pressure way higher than normal. like 20+ psi. You need to overcome the added length and resistance to push beer faster and overcome foaming.

 

[S-Met]

Im not familiar with flash coolers so no guidance on that category.

Regarding jockey boxes, @Vale71 hit most of the key points. Advice on Jockeys are wildly inconsistent because there are so many variables from box to box. Plate chiller vs coils. You want ice only on a plate, drain the water. Coils and shank should always be covered by ice or you may foam from could temps.

25' vs 50' vs 75,120 and 1/4" vs 3/8" tubing size. Line resistance.
Nucleation sites? Tube diameter changes, air leaks?
Box vs keg height (head pressure) run length?
A full keg stays cooler longer than a partial keg in a non-temp controlled environment. You're going to be fighting changing pressure especially on a warm day as the keg drains.

More than a day? Your serving pressure being higher than the beer causing over-carbing. Try and cut the gas if its not in use for a prolonged period.

 

[sudsy]

They used to make flow control faucet shanks, just a thought

 

[javert]

Update.

Finally got the chance to put the flash cooler to test, upped the pressure straight up to 20 psi with a slight fear of something bursting, like a beer tubing which might be loosely attached. Fortunately, got to adjust flow using the flow control valve of the faucet while I was passing Iodophor through the lines.

Great pour. Some nice head, controlled head which could be augmented by pushing the tap to the opposite direction. Witbier wasn't kept on ice during the event although it didn't warmed up completely but came fine all day.

Thanks for the advice guys. Gotta say that the view of the frosted tower with cold water drops on the surface is alluring and probably an advantage against a kegerator which simply blows air through a tower. At least for small events run on a single day the flash cooler has good merits.