Ken The Red wrote:...I'm using 1/4 " vinyl from Micromatic ... The flow is very fast, its hard to tell exactly how fast because its all foam today.
Something is not computing here. With 17' of 1/4" vinyl you would need about 12 psig, using the nominal 0.7 psi/ft value for resistance plus 4.5 psi to overcome the height for a nominal 2 Oz/sec flow and yet you say the flow is very fast with the regulator set at 12 . This implies either that the gauge is off (i.e. actually greater than 12 psi) and/or that the tubing is of lower resistance. You might want to try putting a keg full of ordinary water on (it won't foam no matter how fast you push it) and see what your flow rate is. Water is somewhat less viscous than beer and so will flow a bit faster but if you are getting much more than 2 Oz/sec (12 Oz glass fills in about 6 sec) then the pressure is too high for the line. Try cranking the pressure down until water runs at about 2 Oz/sec and then put the beer back on at the same pressure. If the beer is over carbonated the headspace pressure will be high and it will still foam. The fix for that is bleed, wait a day, bleed, wait a day... without applied CO2. You can have the liquid line hooked up and draw samples during the wait time. Eventually you are going to bleed the keg down to the point where the beer has lost enough carbonation that the flow will slow to a trickle. Now you can put gas back on. The flow at this time should be about 2 Oz/sec and the beer will be undercarbonated. Don't adjust the pressure further. Wait. The beer will recarbonate over a period of a couple of weeks. If it starts to get wild again, which it would do if the nominal calculations are correct because you would need about 17 psig to get 2 Oz/sec and at 34 °F that is going to give you approximately 3.3 volumes, then turn the pressure down. You will have a slower flow but the carbonation level should be about right and you shouldn't get foaming. As you aren't selling beer at a football game the fact that it takes 15 - 20 seconds rather than 6 seconds to fill a glass shouldn't matter. I just checked my own system to see how fast it is flowing. It is a bit less than 1 Oz/sec (I'm running 12 psi at 37 °F for 2.7 vols through about 7' of 3/16" ID which would require 19 psig for 2 Oz/sec so I'm under but the slower flow is just fine as far as I am concerned).
Beer gas is not a terribly practical solution, IMO, as a beer gas bottle is full of exactly that, i.e. gas, whereas a CO2 bottle of the same size contains the same volume of liquid CO2. IOW beer gas bottles have to be refilled much more frequently than CO2 bottle which means more expense and more trips to the gas supplier. Bars that use beer gas usually have on site blenders fed by separate CO2 and N2 bottles (though I do remember seeing a beer truck in the UK loaded to the gills with mix bottles). The N2 bottle is full of gas and so must be replaced more frequently than the CO2 if the blend is 50% or more N2 but many blends are less than this (60 - 80% CO2). Big venues have nitrogen generators (molecular sieves). They sell the beer so fast that if a little O2 gets in there it doesn't matter. But yes, you have the concept right. Total pressure drives the beer but as far as carbonation is concerned it is the partial pressure of CO2 that counts. The nitrogen does not dissolve appreciably - it is much less soluble than CO2.
