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Siphon vs Non-Siphon Gas Tanks

Dip Tube CO2 Tank

What is a Siphon or Dip Tube?

A siphon, sometimes referred to as a dip tube, is like a straw, one normally made of either steel, stainless steel, or copper. There are two different types, with one being external, and another that goes inside and reaches the bottom of the tank. A straw inside of a gas cylinder is typically referred to as either a siphon or dip tube, though some may call it a liquid straw, depending on the region and industry. A tank with a siphon inside is typically referred to as a siphon tank, but are sometimes known as liquid cylinders too.

Similarities Between Regular and Siphon Cylinders

CO2 cylinders and siphon tanks come in different materials, like aluminum and steel, and can be ordered in a variety of sizes. Its measurements are based on weight, typically from between 5lbs and 50lbs. The siphon is out of sight, staying inside the tank. Because of this, they both look the same on the outside. To compensate for the visual similarities, a cylinder will be marked a certain color to identify whether it has a dip tube inside or not. The color itself may vary depending on the company and region. While the latter is the only specific visual difference compared to regular gas tanks, there are a few technical features that make them stand out from the rest.

Differences Between Regular and Siphon Cylinders

Most gases are stored in their liquid state. That liquid gas gets sucked up to the valve, bringing its state of matter into its gaseous state out of the tank. Introduce a dip tube, and it will instead allow the flow of the gas to expel in its liquid state. Some people refer to them as liquid tanks or liquid cylinders for that reason. Besides the physical color marking and internal dip tube itself, a siphon tank will look exactly like a regular gas tank, but their applications vary greatly because of what the dip tube is designed to do.

Now first off, siphon tanks are less commonplace compared to regular, siphonless tanks. Carbon dioxide tanks dedicated to carbonating water and soda, helium tanks blowing balloons, and propane tanks heating grills will not have internal siphons. Although, that doesn’t mean gas tanks with dip tubes don’t have a place or purpose.

Applications For Siphon Tanks

There are specific jobs that will put liquid gases to good use, and that’s where the siphon comes into play! It plays a role in food preservation by refrigerating and storing food for extended periods of time. In some cases, it can aid in softening food too.

It also helps in extracting solvents. Many extraction systems use liquid CO2 because the gas has the ability to separate and dissolve certain substances, making the yield of separated solvents possible. Using liquid CO2 is the cleanest and quickest way to perform this task. Other methods that don’t use it require more time, along with an additional purging process. This efficiency wouldn’t be possible without that siphon inside the CO2 tank. Although, a specific CO2 grade is used for extraction systems, specifically one called supercritical fluid extraction grade (or SFE-grade for short). While we don’t carry that type of grade, it at least goes to show what liquid CO2 is useful for.

Can Any Gas Use a Siphon?

For the most part, yes, but the specifics vary for each gas cylinder. Carbon dioxide tanks are typically given the option of having an internal dip tube. Most other gases probably won’t use that type, but will instead use an external siphon.

Also, not every gas is stored in their cylinder the same way. For example, to be used in its liquid state, oxygen must be stored in a dewar tank. On the other hand, liquid CO2 can be stored in a cylinder. Different gas container types and sizes will keep their gases at specific pressures and temperatures. Otherwise, they may not remain in their proper state of matter inside or outside the tank.

Siphon CO2 Cylinder Safety Concerns

First off, it’s imperative that you don’t accidentally get liquid CO2 out of your siphonless cylinder, or gaseous CO2 out of your siphon CO2 tank. In most cases, the gas’ wrong state of matter is due to the mistake of ordering the wrong type of cylinder. If this isn’t the case however, then the error may be due to improper handling of the gas cylinder itself, where it’s being used upside-down instead of right-side up.


Gas cylinders should remain right-side up at all times. If your CO2 tank, with or without a siphon, is sitting upside down, you risk breaking the gas regulator, leaving an opening on the top of the tank and turning it into an unpredictable rocket. At that point, property damage and severe injuries can quickly occur. The room can also displace oxygen with an overabundance of carbon dioxide, making anyone in the room feel physically ill and have difficulty breathing until it ventilates out and everyone gets fresh air.


Even if the valve doesn’t break or the tank doesn’t fall in this position, it will improperly spray liquid CO2 instead of gaseous CO2. If you absolutely need liquid CO2, an upside down tank is not the way to do it. That’s what a siphon cylinder is for. If you do this with a siphon CO2 tank, you will get gaseous CO2 instead of its liquid form. Still, putting it upside down isn’t appropriate or safe, so you simply need to just swap out your siphon CO2 tank with a siphonless one.


When it comes to storage, siphon CO2 tanks follow the same rule as other gas cylinders. Keep them in a cool and dry location, sitting upright, secured with storage equipment, and away from obstructions, hazards, and all forms of heat. Doing these things prevent them from unnecessary damage, the exposure of flammable materials, harmful temperatures, and the risk of falling and rolling around.


It’s important to understand the many safety concerns regarding gas cylinder operation and storage. There are many different types of safety equipment to use and proper safety protocols to follow too. You can see our collection of articles that focus on safety to learn more.

Ordering Siphon CO2 Cylinders

Our CO2 cylinders are available in different sizes, with or without an internal siphon. We also have a collection of safety equipment to look at in our online shop. As for the tanks themselves, you may rent as many as you need from our ordering page.


If there are any questions or concerns, please feel free to contact us. Call one of our associates at 877-280-5321, and one of our customer service representatives will be more than happy to assist.

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