# Can you push a liquid and a gas into a container at different pressures?

I have a gas ($\ce{CO2}$ for example) and I want to infuse it into a liquid ($\ce{H2O}$ for example). I need a higher pressure of $\ce{CO2}$ to do this. So I push in water into a sealed container (at 7 psi) and add $\ce{CO2}$ (at 14 psi).

Is this possible? Will it back up? What if I use a check valve? Can I use a non-electrical actuator of some sort to let liquid in, and then add gas 'automatically'? What about something that functions like a carburetor?

I need to let the new solution out after it is mixed and also allow a consistent flow if I leave the exit open. If I have a liquid at 7 psi and a gas at 14 psi and I am trying to push them both into a sealed container, how is this done? Letting it out? Doing it on the fly?

I know you do NOT carbonate water at these pressures. Just an example with real gas/liquid.

Pressure is due to the random impact of molecules on the surface, regardless of whether water or carbon dioxide or anything else. Once equilibrium is reached, all components are at the same pressure.

That said, there's no problem using a moving stream of $\ce{CO2}$ to propel and to mix with water at much lower pressure, using Bernoulli's principle. The automotive carburetor and spray atomizer operate on this basis.

The alternative, of course, is to add the water to the container through a check-valve, then add $\ce{CO2}$ at a higher pressure.

The choice is a continuous process vs. a batch process.

• The continuous process is the objective. I have been looking into injectors en.wikipedia.org/wiki/Injector and Aspirators en.wikipedia.org/wiki/Aspirator_%28pump%29 but I'm not sure if they would work like I need. Thoughts? For the record, the automotive carburetor was my initial thought, but I couldn't find anything small for my application. – n0ttsweet Jul 22 '15 at 16:09
• A "perfume" atomizer is smaller than the carburetor, and you could make a really tiny one from glass tubing with minimal flamework, e.g. pull a point, bend it a bit, and mount it in a T-tube. The moving CO2 in the straight top of the T would pull up the water in the vertical. You would need a check valve in the water line. – DrMoishe Pippik Jul 22 '15 at 19:16
• I was think of just 3D printing one... But designing it like an aspirator. The purfume atomizer was suggested elsewhere as well though. It merits a closer look! – n0ttsweet Jul 23 '15 at 20:53

We flow gases and liquids into reactors at 80 bar quite easily. This is not into a sealed (batch) container, but into packed tubes with a back pressure regulator(ultimately)vat the end. The gas pressure is higher than the liquid pressure, which does not lead to gas in-flow due to check valves on the liquid feed. In a sealed container, it would be expected that the headspace pressure would eventually match the gas pressure. If the liquid pressure was lower and the liquid feed couldn't hold the higher pressure, something would fail. A mass flow meter can control your gas delivery accurately. A tube packed with inert material is a cheap way of getting good mixing.

• Interesting. So it sounds like you're suggesting letting the gas pressure be higher, but regulating the flow of gas so that it doesn't overwhelm the liquid? If I need to achieve continuous flow, this might be an issue. In the end I need more volumes of liquid than gas, but a higher pressure of gas than liquid to force it into the liquid. – n0ttsweet Jul 22 '15 at 16:19
• Imagine a glass 2/3 full of liquid, then fill that last 1/3 with N2 and to 1 bar higher than the pressure the liquid was pushed in at. Think Henry's Law. I need to do this, continuously. In my other comment I mentioned aspirators and injectors. What do you think? – n0ttsweet Jul 22 '15 at 16:20

You may want to consider delivering your desired gas in a condensed form, if you want to dissolve nitrogen (using liquid nitrogen) or carbon dioxide (using dry ice).

You would be able to reach high pressures in a sealed container easily by just adding the dry ice or liquid nitrogen to your water. The nice thing is that you won't need any pumps, regulators, valves, etc. A safety valve would keep from accidentally shattering the container.

While this method doesn't lend itself to a continuous flow, and you'll have to carefully regulate temperature to avoid freezing, you may save a lot of time/money by making a series of batches quickly.

• I like it! However, this will be something the customer uses. They cannot prepare batches and I can't effectively keep it under pressure after it leaves my hands to go to them. I need the continuous production no matter what :/ – n0ttsweet Jul 23 '15 at 20:52