The beer tap, especially in conjunction with a compensator tap, is a simple physical process. Nevertheless, it is necessary to master a few tricks to be able to enjoy the freshly tapped. Words like “less are more …” or “a lot helps a lot …” are out of place here …..
To determine the operating pressure of your dispenser, the following must be known:
1. The saturation pressure of the beer. Depending on the beer temperature
2. The difference in height between the barrel and tipping point, and …
3. The cable length
Since the beer contains carbon dioxide (CO2), it is bottled under pressure in barrels. Otherwise, the carbon dioxide would be released, and the result would be foaming. The same applies to the dispensing system; if the pressure is set too low, the carbon dioxide in the beer line is released. The result is a glass full of foam. But now enough theory, so you determine the perfect “Zapfdruck”:
Step 1: Determine saturation pressure
To determine the saturation pressure, the beer temperature must be known. Since it is difficult to measure the temperature in the barrel, it is sufficient to know the room temperature of the storage room. If the barrel is tapped freshly from the brewery, ask the storekeeper for the cooling temperature. (By the way, you can impress properly ;-))
Then determine the saturation pressure using the following table:
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
so far so good, next step …
Step 2: Determine height difference
The difference in height between the bottom of the drum and the tipping point is measured, 0.1 bar pressure per meter is necessary.
Step 3: Determine cable length and friction losses
The pressure losses depend on the length and diameter of the beer pipe. For 7mm pipes, 0.1 bar pressure per 2m beer line is required. For 10mm tubes, it is 0.1 bar per 6m length.
Now we are only a short step away from the perfect beer and thus come to the fourth and final step …
Step 4: Calculate the operating pressure.
This step is particularly tricky as it requires fundamental mathematics knowledge… You may have guessed it, the three pressures determined are added together.
And now a small example, taken directly from life… It is a beautiful Sunday morning, and because the weather is crying for a little barbecue, we spontaneously invite our friends. As a good host, we naturally have a 20 l barrel of delicious Augustinian Hell in the cellar, where a pleasant 10 ° C prevail. The wet cooler, we have in wise foresight the day before in operation (sure is safe). The keg is in the basement, the tap on the ground floor, the difference in height is pretty much 4m. We use 7mm beer hoses, 6m long.
Saturation pressure according to table -> 1.2 bar
Difference in height 4m -> 4m * 0.1 bar -> 0.4 bar
Friction losses -> 6m / 2 * 0.1 bar -> 0.3 bar
Operating pressure: 1.2 bar + 0.4 bar + 0.3 bar = 1.9 bar
How many bubbles per minute should you set?
How many bubbles per minute you should set for your aquarium depends on a few factors.
The most important factors, whether you have a high or low CO2 demand in your aquarium, I summarized here once:
Your aquarium has a higher CO2 requirement, if …
- a strong current prevails
- the water surface is moved strongly
- the pool is heavily lit (from about 0.4 watts per liter)
- many plants are used
- The aquarium has a broad base area, i.,e. also water surface about the volume
Your aquarium has a lower CO2 requirement if …
- little light is used
- Only a few undemanding plants are used
- there is hardly any flow or surface movement
I have found that low-aquarium aquariums manage at 20 to 30 bubbles per minute.
I run aquariums with high CO2 requirements with at least one bubble per second! You should always use a CO2 endurance test and do not permanently exceed a CO2 value of 20mg / liter (otherwise, there is a risk of suffocation for the creatures in the aquarium).
In addition to the bubble counter, you should, as I said, especially on the CO2 value, which prevails in the aquarium. The so-called CO2 endurance test indicates these.
Which values should be set on the pressure reducer/manometer?
The pressure reducer – often referred to as a pressure gauge – has, as mentioned regularly, two Einstellrädchen and also two pressure displays.
On the blue photo at the top is my reducer, which has two printouts. The left round display shows the current working pressure and the right to display the current strength in the CO2 bottle.
The left display is always at about 1 – 2 bar for me. In any case, it should be avoided to reach the red area marked on each reducer with the measuring needle.
The 1-2 bar is optimal for the working pressure (more precise manufacturer-specific information you take from the individual instructions for the use of the pressure reducer).
If the content of the CO2 bottle is running low, the pressure indicator, the right-hand display, of course, also drops. Then you should check the CO2 supply regularly, and should the bottle be empty, refill it!
This is shown by the pressure gauges on the CO2 system.
Using the example of the pressure reducer shown, the upper-pressure gauge indicates the working pressure. Here you can already see that this is under a bar. The working pressure is the pressure that is in the hose and the CO2 diffuser, and that is needed, for example, to press the CO2 through the delicate membrane of the CO2 diffusers.
The right manometer shows you the contents of the CO2 bottle. The higher the pressure, the more CO2 is left in the bottle! At my 2 KG bottle is about 60 bar displayed when it is still full.
CO2 endurance test to control CO2 intake
So you do not always have to look in the aquarium cabinet on the pressure gauge to check the bottle contents, I take myself a so-called CO2 endurance test at hand.
CO2 endurance tests are carried out with a test liquid (for example, with the Aqua Rebell CO2 endurance test liquid * eternally far) filled, which respond to the CO2 content in the aquarium.
This must, depending on the manufacturer, from time to time, be replaced, but it is very reliable!
The liquid in the transparent CO2 endurance test (also called “drop checker” in German) then changes to a different color depending on the CO2 content. When the optimum CO2 level is reached, the liquid turns green!