A tandem seal is the Grundfos name for a shaft seal system where an additional sealing chamber has been mounted on the existing shaft seal. The purpose of the sealing chamber in a tandem seal pump is to guarantee that liquid does not leak from the pump housing. By flushing the sealing chamber with a neutral fluid, excess fluid in the centrifugal pump is absorbed/removed.
A Grundfos centrifugal pump with a tandem seal offers several advantages. The flushing fluid between the two seals is pressure-less and gives several advantages to the product-side shaft seal such as:
- No evaporation in the sealing gap. This prevents the formation of deposits as well as crystallisation on the flushed fluid side
- The flushed fluid lubricates and cools even when the pump runs dry or runs with vacuum