The pantograph type is the most widely used seal design on external floating roof storage tanks.  It provides a long service life and is of a dynamic design that takes into consideration irregularities in the tank shell construction.

The scissor seal is designed with a shoe plate that extends into the product to ensure good vapour retention.  The design of this seal is for good performance in tanks with a large rim gap, and even in tanks with shell anomalies.

The tube containing compatible liquid is located directly on top of the stored product, and therefore eliminates the potential vapour gap. The liquid filled tube provides a dynamic 'bumper' between the tank shell and the roof.

Available as product or vapour mounted, the flexible foam filled primary rim seal consists of a series of foam blocks which are covered by an envelope and held down by steel plates for a high efficiency sealing solution.