beer foaming and spitting

my homemade draft system foams and spits on first pull of tap,but settles after 3-4 seconds, then it pours perfect,then after sitting for maybe 10 minutes it does the hole thing again. i have replaced beer lines ,facet,shank, beer keg is in basement,in fridge,temp. reads 30deg. line runs are,10feet 5/16,4feet 3/16 and rise is 7-9foot,all line is insulated with 1/2 inch pipe insulation

sorry about the copy message,i am new to forum writing,submitting etc.

tfetter said:

in fridge,temp. reads 30deg.

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Is this a typo? That's awfully cold to be storing your beer. Maybe you're getting some frozen beer in the lines at the first pull after it's been sitting for 10 minutes.

-Joe

I would guess that you are getting the CO2 coming out of solution due to the pressure loss in a 7-9 foot vertical rise. The temperature rise in the line could also be contributing to the problem. What is the pressure in your keg?

My guess would be warm lines. Just insulating them will not necessarily keep them cold. Most people will run some sort of cooling system (air cooled with a fan blowing into tubing with the lines or a glycol/water/or mix of the two system being run by a pond pump).

I agree with the other responses, 30 seems a bit too cold, but shouldn't be the primary cause of the foaming. Warm lines due to the length of run would be my bet.

A 9ft vertical rise equates to a 4 psi pressure loss. So if your keg is at 12 psi, then the tap is at 8 psi (without any flow) - you will get a significant amount of CO2 coming out of solution. The warmer temperature of the lines also contributes to carbonation loss.

Cooling the lines won't make the problem go away completely.