Basic knowledge about the external floating roof tank:
The floating roof tank (FR tank) is broadly divided into External floating roof tank and internal floating roof tank (IFR tank). The floating roof tank (FR tank) does not have a fixed roof. It is open in the top and has a floating roof only.
The external floating roof tank consists of an open-topped cylindrical steel shell equipped with a roof, which floats on the surface of the stored liquid. The roof rises and falls with the liquid level in the tank.
As opposed to the Fixed roof tank, there is no vapor space (ullage) in the floating roof tank, very low liquid level situations are not included. In principle, this eliminates tank breathing loss and greatly reduces the evaporative loss of the stored liquid. There is a rim seal system between the tank shell and roof to reduce rim evaporation.
The floating roof has support legs hanging down into the liquid. At low liquid levels the roof eventually lands and a vapor space forms between the liquid surface and the roof, similar to the fixed roof tank. The support legs are usually retractable to increase the working volume of the external floating roof tank.
What advantages does the external floating roof tank have?
The external floating roof tank is usually installed for environmental or economical reasons to limit product loss and reduce the likelihood of emission of volatile organic compounds (VOCs) and other potential air pollutants.
Normally, the roof of the external floating roof tank rests directly on the surface of the stored liquid, leaving little vapor space and consequently leading to a much lower risk of rim space fire.
What products are suitable to store by the external floating roof tank?
The external floating roof tank is storage tank that is commonly used to store large quantities of crude oil, condensate and so on petroleum products. Medium flash point liquids such as naphtha, kerosene, diesel, and crude oil are usually stored by the external floating roof tank.
