How to calculate the dispensing pressure to be set for your dispenser
Tapping beer through a dispensing system, especially in connection with a compensator tap, is a simple physical process. However, many dispensing systems are set incorrectly, making dispensing considerably more difficult.
The tap pressure is often reduced when it foams. A mistake!
Because beer contains carbon dioxide, it is filled under pressure. Without pressure, the carbon dioxide would release and foam would form. If there is too little pressure in the beer line, the carbon dioxide releases and only foam comes out of the tap. Now the pressure has to be increased again until the carbonic acid dissolves in the beer and there is no more foam in the line.
The correct dispensing pressure can be determined in 3 steps.
1. Determine the saturation pressure using the following table
Determine the beer temperature (= beer cellar temperature) and read the associated saturation pressure.
5 ° C = 0.8 bar 10 ° C = 1.2 bar 16 ° C = 1.7 bar 22 ° C = 2.1 bar
6 ° C = 0.9 bar 11 ° C = 1.3 bar 17 ° C = 1.8 bar 23 ° C = 2.2 bar
7 ° C = 1.0 bar 12 ° C = 1.4 bar 18 ° C = 1.9 bar 24 ° C = 2.3 bar
8 ° C = 1.0 bar 13 ° C = 1.5 bar 20 ° C = 2.0 bar 25 ° C = 2.4 bar
9 ° C = 1.1 bar 14 ° C = 1.5 bar 21 ° C = 2.0 bar 26 ° C = 2.5 bar
Warning: In summer it often happens that beer in the barrel is well over 20 ° C. In winter it is often only 8 ° C.
2. Determine the delivery pressure
A pressure of 0.1 bar is required per meter of height (barrel bottom to tap) (regardless of the pipe cross-section).
Cable length / friction losses
The friction losses depend on the length and diameter of the beer line.
With 7 mm lines, 0.1 bar per 2 m line length is calculated.
With 10 mm lines 0.1 bar per 6 m line length.
3. Calculate the tap pressure
Now the 3 pressures for saturation, height difference and line length are added together
18 ° C beer temperature (in the barrel), 2 m height difference and 4 m line length with a 7 mm.
1.9 bar (saturation pressure)
+ 0.2 bar (height difference)
+ 0.2 bar (line length)
= Tap pressure of 2.3 bar.
In practice, you should never drop below the determined pressure. With a compensator tap, the minimum pressure is 1.2 bar (do not fall below!). If in doubt, increase the pressure rather than lower it!
Important when storing opened barrels, the pressure in the barrel should always correspond exactly to the saturation pressure. So regulate the pressure on the pressure gauge down to the saturation pressure, to do this let go of the excess pressure by pulling off the pressure relief valve. Do not turn off the CO2 so that a constant pressure is guaranteed.
So you guarantee the freshness of the beer even over a longer period.