Nitrogen foam

[sean6120]

Any ideas on why I have massive foam when I use my nitro bottle which is or should be 72/25 mix but when I switch back to my co2 bottle with a stout faucet I get a good head just not as creamy of course. Nitro pressure at all different settings still all foam that takes extremely long tome to cascade away. And I do like my stouts served at a colder temp that some around 35-37 not sure it that matters.

 

[Pie_Man]

I am no expert in this area, but it seems like there is too much pressure on the nitrogen. Perhaps your pressure gauge on the nitrogen tank is inaccurate giving you a faulty reading? Have you tried bleeding the nitrogen line and starting with the gauge very low?

 

[augiedoggy]

i've been told anywhere from 22 to 28lbs of pressure is good but it really depends on the diameter and length of the beer line from the keg to the tap.... that has a hug effect on things.. there is a formula to it all which you can google to find.

 

[Shockerengr]

Did you carbonate the beer first on regular co2? Usually if you are getting massive head while on nitro blend it's a sign that the beer has been overcarbonated.

you only want about .7-1.1 volumes of co2 in the beer.

 

[Shockerengr]

Also, for a nitro setup, line length / size doesn't matter as you aren't trying to balance the lines. The restrictor plate in the faucet provides all the resistance needed. It also strips nearly all the co2 out of solution, which is why you want to avoid having too much co2 in the first place. The Nitrogen is just there to boost the serving pressure and force it out quicker, giving the finer head.

 

[augiedoggy]

Also, for a nitro setup, line length / size doesn't matter as you aren't trying to balance the lines. The restrictor plate in the faucet provides all the resistance needed. It also strips nearly all the co2 out of solution, which is why you want to avoid having too much co2 in the first place. The Nitrogen is just there to boost the serving pressure and force it out quicker, giving the finer head.

This is good to know as its not what I had been told in the past... what your saying makes sense but I would have to think the line size and length still have a final effect on proper serving pressure regardless since they do in fact effect the flow rate and pressure to the plate...

I have a guiness tap and use beer gas for it but I do carbonate my beer prior to connecting it and find I need to lower my pressure a lot compared to what Guinness states (28lbs) to compensate for that.... for that reason I guess anyone who buys a keg of Guinness and trys to serve it on a regular beer tap with co2 will have completely flat beer with no head? can anyone confirm this?

 

[Shockerengr]

Well crap...had a nice long post...and lost it cause i wasn't logged in on this computer. D'oh!

I'll summarize:
Line lengths can matter - but generally, it's not the source of problems for most stout setups like it is for normal beer faucets.

With Nitro setups, you still need to ensure that the beer is properly carbonated....the nitrogen is just a neutral gas used to help force it through the stout faucet. So if it's overcarbed, you'll get tons of foam just like if a normal beer is overcarbed.

The calculations for carb levels with nitro are pretty straightforwards (google Dalton's law of partial pressures for background) Basically take the percentage CO2 in your gas blend times the pressure at the regulator (for instance .25 * 28 psi = 7psi of co2), then plug that into your favorite carb calculator. If you're much over 1 volume of CO2, you'll probably have foam problems. if under .5 volume, probably won't get any head at all.

Fixing the issue is the same as you would for a normal beer, although if you are undercarbed, it's easy to carb on normal CO2 then switch back to beer gas and purge.

 

[Kingbogart]

Here is a calculator that essentially does what Shockerengr is talking about.

 

[Shockerengr]

Here is a calculator that essentially does what Shockerengr is talking about.

Excellent!

 

[Brewerforlife]

http://www.draughtquality.org/wp-content/uploads/2012/01/DQM_Full_Final.pdfRead this: