Tag: Leak detection

August 5, 2025 – My Keg is Flat Again?

August 5, 2025 /

When I got my keezer (kegerator), it had one tap and therefore one keg. There is probably room for four kegs of this type inside the refrigerated space. the vessel is called a Cornelius keg, often called a ‘Corny’ keg and used by Pepsi Co. That makes a lot of used ones available in the market for whatever reason.

My strategy if you will is to have one on tap, one in waiting and one used extensively for flushing the lines. I have considered adding more taps but realistically I should not make drinking beer easier. Plus, it is a lot a work to brew and flushing the lines is often not done after use so for now, one is plenty. The point is that I have added two more kegs to the system.

Both of the kegs I have purchased were used. In fact both were also dirty. One had Mountain Dew under pressure in it. I don’t recall the second one other than to say I know it was dirty. But, I imagine that these things are not taken out of service for no reason. As a result, I have taken to having to give them a once, twice and often three times over to figure out what is wrong.

Aside from being dirty, the most common problem is leaking. Even though I have had extensive work in scientific air analysis, the tools I have at my disposal are pretty rudimentary. Most of it involves guessing and checking. The one thing that works pretty well is the soap solution looking for bubbles. The one I am showing in the picture comes from the plumbing section of a home improvement store.

You can make your own solution with dish soap and water. I don’t honestly know what the mixture is and I suppose it probably matters which detergent you use because of the factory concentration. The reason I chose to buy one is that the cap comes with a brush and so you can swab areas of interest. The one we used in the lab was a squeeze bottle with a tube at the nozzle so you could really target small areas but it is $25 a bottle.

I think it is pretty obvious how you know that there is a leak. That being said, how did I know? I opened the tap handle and nothing came out. Normal keg pressures should be around 15psi and there should be enough pressure in the vessel to fill a cup without the source pressure on (again laziness about the proper steps). But if I did things right, you should not hear gas going into the keg when you turn the cylinder valve because everything should be at equilibrium in this closed system.

When it comes to troubleshooting this system, the distribution line likely only needs to be checked once for leak Go to each break in the line and swab the joint under pressure. If it leaks, that joint will need to be tightened (only occasionally loosened depending on the connection type but beyond the scope of this article). Honestly, I only do this if during my initial test, I lose pressure. This is called ruling out the variables.

By far and away the most frequent failure parts are the action parts. These are things like valves and O-rings that seal connections. If no leaks are found around the valve, then try replacing O-rings. These are designed as replaceable parts anyway and it could have gotten damaged during transit or worn from heavy use. If your vessel leaks, then it is almost certainly junk unless you can weld on stainless steel.

I found that on my keg in the picture above was leaking around the main seal O-ring. Even my soap test did not reveal the leak and it would occur over the span of three days or so. I also knew that my O-rings on the valves were OK because the keg leaked whether it was connected to the distribution line or not. Other kegs I have did not leak and so it wasn’t the other end of the connection either.

Generally speaking, these tests should be done under system pressure. This should reduce the risk of contamination from the soap. Cranking up the pressure should make leaks more obvious but it is possible to cause new problems, so be careful. The one thing that I also wanted to add with soap is to make sure product surfaces are cleaned after testing unless you like soapy beer.

End Your Programming Routine: This troubleshooting technique works for beer kegs, water lines, air lines etc. In plumbing, lines are pressurized to prove that they are solidly connected (generally new construction). One final thing, the air molecules are generally smaller than liquid water, so a leak in an air line is much more likely than a water line. So-so connections can still hold water that don’t stand a chance containing gasses for long term.

April 6, 2022 – Leak Testing

April 6, 2022 /

When I worked in environmental chemistry. We has an entire lab filled with instruments that used scientific grade gas 24/7 whether we were running tests or not. We had an entire bank of cylinders because we wanted redundancy and not to come in on the weekends.

A leak meant lost analysis time, wasted money and potentially even a compromised sample. They weren’t common but they did happen. When we changed cylinders we did them three at a time. Leaks are serious business in chemical manufacturing but they are something the regular person should know about as well.

What is driving this today? This is triggered by my keg testing. One of the simplest, cheapest and best ways is to do this is use a soap solution. Of course, the this is only works when the piping is under pressure. The good news is that vacuum lines are pretty rare.

When new plumbing is installed, the system is first sealed and pressurized. The system is left overnight and pressure loss is measured overnight. Any amount of loss is clearly a leak. What happens next? You have to find the leak.

The first place to check is all of the fittings or joints. Ninety-nine percent of the time, a leak is sourced from a poor connection. Glued in joints have to be cut and replaced. Screwed in fittings may have too much tape or not enough or are not supposed to have any thread sealant. Compression fittings may be tightened to much or not enough depending on whether they have rubber o-rings or not. Ferrule type fittings sometimes the ferrule is not seated properly. Those have to be replaced.

There are gas detectors for propane or natural gas. Liquids are often observable as drips. As I said above, my go to is a soap solution. The one in the picture below I purchased because I wanted some kind of applicator so I didn’t make a mess all over the place. You can look up recipes online but essentially is is a very dilute soap and water solution. Escaping gas forces bubbles to form at the location of the leak.

To use, open the bottle. It has an applicator brush like PVC cement. You simply wipe the solution around the fitting or suspected area of a leak and look for bubbles. I wanted to check all of the fittings around the regulator and gas lines because I was unsure as to the viability of all the gaskets and O-rings. Turns out that I didn’t find any leaks.

End Your Programming Routine: Leaks can be expensive. But more so than that they are inconvenient. Gas suppliers are open Monday through Friday, 8-5. Imagine that you are in the middle of your party and you lose your CO2. That would be a bummer. It would probably be a good idea to get a second tank for that reason. But again, this is still an experiment at this stage. If I decide to make a full commitment, then I will definitely get a second tank.