Comparisons between internal floating roof storage tank and external floating storage tank

As a kind of important oil storage tanks, floating roof tank is different with fixed roof tank, because that floating roof tank is equipped with a floating roof, which floats up and down with the liquid level, while fixed roof tank isn’t. Floating roof tank is widely used to store volatile oil, like gasoline, aviation kerosene, diesel oil, crude oil and other light oil.

internal floating roof tank

external floating roof tank

fixed roof tank

Floating roof is the core component of floating roof storage tank, which is divided into two types: "external floating roof" and "internal floating roof". Because the flexible floating roof deck can float up and down to close to the liquid level, gas space above the liquid level can be greatly reduced, thereby greatly reducing the evaporation loss of the stored oil. The external floating roof tank has a floating roof deck which is covered on the surface of oil, and floats up and down with the oil level. As there is almost no gas space between floating roof deck and oil level, the evaporation loss of stored oil can be greatly reduced. Internal floating roof tank is a floating roof storage tank which is covered with a fixed roof on the floating roof, which can prevent the tank itself from been suffered from wind and rain, guarantying the quality of stored oil under the floating roof.

Although there are a lot of external and internal floating roof tank advantages, what are the differences between them? When we choose the floating roof storage tank, how to choose which is more suitable for our storage requirements between these two kinds of storage tanks ? Here is a brief introduction about how to choose a suitable floating storage tank for your storage solution, hope it can help our customer has a more clear understanding when they choose floating roof storage tank in the future.

Differences between internal floating roof storage tank and external floating roof tank

The sending and receiving process of the stored liquid is same, the difference between external floating roof storage tank and internal floating roof storage tank are as follows:

• There is a floating roof deck on external floating roof tank, liquid stored in the tank can be separated from the air, reducing air pollution and the danger of fire and explosion.
• Internal floating roof tank can effectively prevent the stored oil from being polluted by wind, sand, rain, snow, or dust, guarantee the oil quality under various weather conditions, is famous as “all-weather storage tank”.
• Both internal floating roof tank and external storage tank can reduce the evaporation lose.
• On the base of the same floating seal, compared with external floating roof tank, internal floating roof storage tank can further reduce the evaporation loose, which is because the shelter of fixed roof, and the gas phase layer between fixed roof and internal floating roof deck has a more remarkable heat insulation effect than external floating storage tank with double floating roof deck.
• There is no rain and snow load on the floating roof deck of internal floating roof storage tank, which is differ with the opened floating roof deck of external floating storage tank. Floating roof deck load is small, structure is simple and portable, internal floating roof can save central drainage tube, rotational ladder and other accessories on the floating roof deck. What’s more, internal floating roof tank is easy to construct and maintain, and the material of the floating seal part can avoid the sunlight exposure and aging.
• Compared with internal floating roof storage tank, external floating roof tank has many advantages, which is more and more widely used, as well as a kind of storage tank with a promising future. Perfect designed internal floating roof storage tank is the best method to control the evaporation loss of the fixed roof tank. Internal floating roof tank can be used to store gasoline, jet fuel and other volatile oil, And liquid chemicals like aldehydes, alcohols (methanol, ethanol), ketones (acetone), benzene (benzene, toluene, xylene, styrene).

Conclusion

In summary, compared with external floating storaeg tank, internal floating roof tank can better prevent the evaporation of the liquid, and avoid more external pollution. However, internal floating roof storage tank can only store liquid, it is not suitable for the storage of liquid and solid mixture, and the special designed structure with both internal and external roof will also increase the investment cost of the storage tank.

Thus, when we need to store volatile liquid, internal floating roof tank is a better choice to reduce the volatilization. However, when the stored material is the mixture of liquid and solid, or the investment cost is limited, we can choose the external floating roof storage tank.