Originally Posted by msa8967
I tried carbing at 35 psi and then serving at 10 psi using 20 ft of 3/16 line and still got too much foam. I am going to reduce the pressure to 25 psi and try again.
Thanks for the advice everyone.
I have made numerous attempts to do what you are trying. Using intermediate pressures is very problematic.
The best results come from either balancing the system for pressure dictated by the vols of CO2 and serving temperature; or, for short term only, by using a shorter, large(r) diameter serving hose, and reducing the pressure and shortening the hose until it does not foam. The shorter the hose, the better.
If you are not going to be able to reliably maintain the temps of the entire serving setup, reducing the pressure is much easier to manage. The pressure only needs to be high enough to just push the product. For long(ish) periods between serving, the pressure will need to be bled from the keg. The product will still stay close to the original carb level for a several hours even with the small losses to CO2 coming out of solution. Colder temps help minimize this effect.
A short, larger diameter hose will reduce foaming significantly. As I mentioned before, the shorter hose, the better. Going too much bigger in one jump than a smaller upstream orifice can sometimes cause cavitation/degassing issues, but 1/4" ID, and even 5/16" ID, seems to work OK for connecting to standard corny dip tubes and QDs.
At low pressures using short hoses, most issues are due to velocity. Just keep reducing the pressure of the reg, and bleeding the keg, to slow down the flow. If you still get foaming at too low flow rates, shorten the hose. If you still have issues, there is a cavitation/degassing site somewhere in the the line.
This approach is backed up by physics. It is no different than why you can pour soda from a bottle, or drink it using a short straw, without it foaming violently.