Tank storage equipment

Is it an open or closed cistern?

A major difference between an open and a closed cistern is the actual tank construction, and how it is affected by wind, rain and snow.

Open and closed cisterns knowledge bank

Closed cistern

A closed cistern, i.e. a cistern with a roof, does not have the problem of water entering the cistern or snow weighing down the floating roof. This means that the floating roof used in a closed cistern can be lighter and with a lower height compared to a floating roof for an open cistern. The internal floating roof is often made of aluminium.

As the seal will not be subject to major external stresses, the actual sealing material around the floating roof is made of a lightweight material. The design of a thin floating roof leaves less space for the seal, so it is important that the seal in a closed cistern does not build up too much height. A well-designed seal for an enclosed tank ensures maximum amount of stored product.

Open cistern

An open cistern is constructed with a floating steel roof and requires a more robust seal. There are a variety of different types of floating steel roofs for open cisterns and it is important to choose the right type of seal and the right material for a specific steel roof. In addition to the seal being adapted to a particular type of floating roof, the seal also needs to be able to withstand the external impact of wind, rain and snow.