Siphon vs Non-Siphon Gas Tanks

Dip Tube CO2 Tank

What is a Siphon or Dip Tube?

Most gas cylinders store the gas itself in its liquid state, and its expulsion brings it to its gaseous state. A siphon allows the flow of the gas to expel in its liquid state. This concept is comparable to drinking a beverage with a straw. The actual siphon portion of the cylinder is normally made of either steel, stainless steel, or copper. This “siphon” has different names depending on the region and industry. It is also known as a dip tube, liquid straw, or is generally referred to as a liquid cylinder, liquid tank, or siphon tank. It's always best to use the expression of "siphon" or "dip tube" cylinder if a cylinder with a siphon is needed.

Siphoned Gas Cylinders

Depending on the type of gas cylinder, gas tanks normally store gas in gas form.  If it's a liquid state cylinder, there is always some space left over above the liquid stored inside. The siphon is meant to extract the liquid at the bottom of the cylinder. This allows liquid to dispel from the cylinder instead of gas. Normally, if a cylinder has a siphon built in, it is painted a particular color depending on the gas provider. This is done to prevent confusion as to which cylinder has a siphon or not.


Siphoned cylinders can be used for many purposes. Liquid CO2, for example, is used for flash freezing and refrigeration, but can also be used in association with health care. Respiratory issues and surgeries can be treated using liquid CO2. It’s even in the entertainment industry. Liquid CO2 can be used for Cryo Jets to produce cold, artificial smoke. These effects are used in many concerts and theatrical shows across the world. Liquid Nitrogen is used for similar applications.

Non-siphoned Cylinders

Most compressed gas cylinders don’t come with siphons. Non-siphoned cylinders dispels content from the empty space above the liquid, (if stored in its liquid form) which allows it to dispel only gas. These are used in many industries, from entertainment to medical. Non-siphoned cylinders are frequently used for dispensing beverages such as beer and adding carbonation to water to create sparkling water and soda. All cylinder should be stored in their upright position to ensure it is used appropriately. For example, if a CO2 cylinder is laid down it could dispel liquid CO2 in a non liquid CO2 application, which could cause severe problems. Please refer to the article linked for Cylinder Safety.

Can Any Gas Use a Siphon

For the most part, yes. But not all gases will be stored in cylinders (commonly referred to as gas tanks). Some gases have to be stored in different gas containers to keep them at appropriate pressure and temperature for them to remain in their gas or liquid state. 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.

It is important to know about the many safety concerns when handling any kind of gas. Each gas is meant to be used and handled differently. Using carbon dioxide is very different compared to helium, nitrogen, and propane. Make sure you understand what each gas is capable of and what makes them different from each other before you get involved with these gases.

If any questions or concerns please feel free to contact us. One of our customer service representatives will be more than happy to assist.

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