This article is part of a series, if you have not read the previous articles please check them out first: Draft Beer 101, Draft Beer 102 & Draft Beer 201
We covered how you can use information provided by the brewer and gathered by you to figure out the pressure needed. However, what if you don’t have that information or you’re concerned it’s not correct?
Physically Checking
So the most direct way to get this information is to get a pressure gauge, hook it up to the keg, and get a reading of how much pressure is in the keg. Then you can set the pressure of your draft system to that number, tap the keg, and be very close to exactly where you want to be.
Pros-
- No math!
- No need to look up Co2 levels!
- If the co2 in the keg is different than expected, the gauge will let you know immediately.
Cons-
- You need to have a pressure gauge!
- You need to have the keg at the location and temperature you want to tap it before you can measure.
Pressure gauges require cleaning and maintenance on par with anything else that comes in contact with beer! They need to be kept clean and sterilized before every use. Every time you tap a keg you create a slight risk of infection if proper, sterile procedure isn’t followed.
If you are using a mixed gas system, you will still have to do math!
How to build a pressure tester:
First here is what you need…
- Pressure gauge
- 1 1/4 NPT to barbed hose fitting ID: 5361K53
- 6 inches of 5/16th inch ID Vinyl gas hose
- 1 5/16th inch id tailpiece
- 2 Screw clamps
- 1 Beer coupling nut
- 1 Neoprene washer
- PTFE Plumbers tape
- 2 Shut off valves
- And the appropriate coupler for the keg.
In addition you’ll need a screwdriver and possibly a utility knife to put this together.
Once you have all the pieces, easy to order online (from the above links), or you can get most of this from a good home brew store, you can then assemble it.
Step 1. Screw the pressure gauge into the 1/4 NPT to barbed hose fitting, using some plumbers tape to ensure a good seal.
Step 2. Firmly push the gas hose onto the barbed hose fitting. It doesn’t have to go all the way up, but should be firmly attached. Use one of the screw clamps to here to hold the hose in place and maintain pressure.
Step 3. Place the second screw clamp, untightened, onto the gas hose, followed by the beer coupler nut. Then push the hose firmly onto the tail piece. The Coupler nut will fit nicely over the end of the tail piece. At this point tighten the screw clamp over the center of the tailpiece (now inside the hose).
Step 4. Place the Neoprene washer inside the beer coupler nut, and hand tighten it onto one of the shut off valves.
Step 5. Clean and sanitize the device.
Now that it’s built, you can attach this with the shut off valve to the gas input (or for some couplers beer output) of a standard beer coupler– whatever is appropriate for the keg you wish to test. Use the second shut off valve on the whichever input or output is already covered, and shut both valves. Then you can tap the keg, open the valve that leads to your gauge, and observe the pressure present in the keg.
Now, if you are using a 100% co2 system, and tapping the keg at the same time and temperature as this reading, you can set the pressure at the regulator to be equal to that shown on the gauge, plus 2 psi to compensate for slight changes in the system.
However, if you are tapping the beer later, or using a blended gas system, what you can do is use this Mcdantim Calculator to determine the Co2 volumes in the beer
Then, when you are ready to tap, simply use the steps laid out in the previous article to determine the correct pressure.