Author Topic: Dispensing Soda  (Read 4530 times)

Offline hokerer

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Re: Dispensing Soda
« Reply #15 on: August 31, 2011, 07:06:46 PM »
Don't you want to see the pressure at the end of the hose with the tap open?  With the beer not moving through the line, the pressure's not really gonna change much.
Joe

Offline darkmorford

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Re: Dispensing Soda
« Reply #16 on: August 31, 2011, 10:09:32 PM »
Good point. I hadn't thought of that. How does one measure that, then?

Offline Joe Sr.

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Re: Dispensing Soda
« Reply #17 on: September 01, 2011, 07:28:35 AM »
Did you bleed off pressure from the keg before serving?

Or is it still at the 55psi or so that you used to carbonate?

It could be that you have so much head pressure in the keg that it's pouring much faster than you would expect.  If the keg is under greater pressure than the regulator is set at, you aren't using the tank at all right now.
It's all in the reflexes. - Jack Burton

Offline darkmorford

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Re: Dispensing Soda
« Reply #18 on: September 18, 2011, 03:11:02 PM »
Well, after a bunch of experimenting and no luck getting a decent pour, I finally bit the bullet and bought a mini-fridge to get the keg cool. I put the keg in a couple hours ago, and while I'm waiting for it to chill I want to make sure I've got my expectations straight.

I checked the pressure on the keg just before I put it into the fridge: it was 43 psi at room temperature (74 degrees or so), which BeerSmith says is about 3.2 volumes of CO2. It's not currently hooked up to the gas tank, and so my understanding is that the pressure will drop as the keg gets colder. If I calculate 3.2 volumes at 38 degrees (serving temp) BeerSmith estimates around 18.5 psi. So do I wait for my pressure gauge to read that low to know it's ready to serve, or am I wrong about the physics here?

Offline tschmidlin

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Re: Dispensing Soda
« Reply #19 on: September 18, 2011, 03:27:35 PM »
There's no guarantee it will work out that way, and in fact, it probably won't.  The pressure will drop, but how far it drops depends on not just the temperature, but the volume of liquid and headspace in the keg.

I would vent the keg once, let it get cold, and then see where the pressure balances.  Adjust from there.
Tom Schmidlin

Offline Joe Sr.

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Re: Dispensing Soda
« Reply #20 on: September 19, 2011, 01:37:23 PM »
I suppose I missed it in your original post, but I've never seen a good pour at room temp.  If the beer is warm I would expect foam and lots of it.

Chilling the keg should be the trick.
It's all in the reflexes. - Jack Burton

Offline darkmorford

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Re: Dispensing Soda
« Reply #21 on: September 24, 2011, 02:21:39 PM »
Okay, keg is at ~38°F, pressurized to 24 psi, which BeerSmith says should give me the 3.7 volumes of CO2 I'm looking for. (The gas tank is in the mini-fridge as well, if that matters.) Ten feet of 3/16" vinyl tubing on the output, ending in a Cobra picnic tap. It seems the tubing restriction is right around the 2.2 psi/ft that Tom mentioned earlier, because the flow rate at the end is about 2 oz/second, which I understand is about ideal for a tap setup.

The problem is that even though the pressure and flow rate are correct, I'm still getting mostly foam when I pour. I'm starting to wonder if it has to do with the sweetener in my soda syrup, since I know commercial diet sodas tend to fizz up more than their corn-syrup-sweetened counterparts. (This particular syrup uses Splenda.)

Any ideas how I can fix up this last little problem?
« Last Edit: September 24, 2011, 02:26:54 PM by darkmorford »

Offline tygo

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Re: Dispensing Soda
« Reply #22 on: September 24, 2011, 03:45:15 PM »
I believe this was mentioned above but my experience is that I don't get 2.2 psi/ft restriction from 3/16" line.  Right now I've got a golden ale set at about 3.2 volumes (19 psi at 38F) and I'm using 15 feet of line and I still get a pretty nice amount of head on the pour.
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Offline Joe Sr.

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Re: Dispensing Soda
« Reply #23 on: September 25, 2011, 05:20:20 PM »
Served root beer today, carbed at 45 psi, served at head pressure.  No problems. A tad foamy, but the kids loved it regardless.

I don't recall how many feet but I've got a big ol' coil of tubing hanging off the keg.
It's all in the reflexes. - Jack Burton

Offline darkmorford

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Re: Dispensing Soda
« Reply #24 on: October 01, 2011, 03:13:23 PM »
Well, this is curious. The keg finally kicked, so I rinsed it out and dumped a few 2-liter bottles of store-bought soda into it. It's chilled to 38° and pressurized at 25 psi (with the CO2 tank and regulator in the fridge as well), just like I had it set before. But now the same amount of tubing is giving an almost-perfect pour! (It's coming out a little flat, so I might bump the pressure a couple psi and see what that does.)

I'm thinking that the last batch got messed up because I had carbed it at room temperature before sticking it into the fridge. Not sure how much sense that makes, but it's pretty much the only thing I changed between that batch and this one. Now I just need to find the local Pepsi supplier and see if I can buy some Mountain Dew syrup from them...