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

What is the difference between external floating roof storage tank and inner floating roof storage tank?

First, different functions
1. External floating roof tank: an open cylindrical steel storage tank for storing volatile petroleum products such as crude oil, gasoline or kerosene.
2. Internal floating roof storage tank: a storage tank that serves as a restriction.

Second, different characteristics
1. External floating roof tank: the external floating roof rises or falls with the liquid storage level.
2. Internal floating roof storage tank: a top cover made of light material is placed on the section.

Third, different advantages
1. External floating roof tank: there is a central drainage system on the floating roof to ensure that the accumulated water can be discharged smoothly in rainy and snowy days to avoid sinking accident.
2. Internal floating roof storage tank: the internal floating plate floats on the liquid surface, so that there is no evaporation space in the liquid phase, which can reduce the evaporation loss by 85% ~ 90%; in addition, the air and liquid storage are blocked by the floating plate, which can reduce the air pollution and the degree of fire risk at the same time.