PSI-Polymer Systems

PSI-Polymer Systems Inc.’s New Lip Seal Provides Gear Pump Leak-Free Performance for Viscosities as Low as 100 Centipoise Conover, NC (October 16, 2013)

Since its founding, PSI-Polymer Systems Inc.  has pioneered the move away from traditional stainless steel seals on gear pumps, to create a more reliable seal, immune to the catastrophic damage that can normally occur if material contact with the steel gear shaft is made.   As with steel seals, the company’s bearing-grade bronze seal relies on material viscosity to create a seal between the seal grooves and gear shaft.  However, some materials, such as very low-viscosity coatings, high melt PP, HMA, etc,, have viscosities so close to water that the material will leak past a standard seal.  In these cases, the traditional solution has always been the addition of a packing gland, which requires occasional maintenance to tighten the gland against the rotating gear shaft when the seal begins to leak.

For these extremely low viscosity applications (100-250,000 centipoise), PSI has created a new “Lip Seal” for its gear pumps that effectively eliminates packing gland leakage and maintenance.   This lip seal includes a plate at the end of the seal that locks the rings of the packing seal in, making the seal tight internally as well as externally. Any material that migrates across the seal will flow into the packing first, then the new lip seal cartridge, and finally the ‘follower plate’ that is sealed with an o-ring. These three components combine to eliminate leaks from even extremely low viscosity materials.  For applications when the gear pump needs to pull a vacuum, a double lip seal option is the perfect solution.

 “The lip seal is another step in the evolution of a process we began a long time ago at PSI to move away from seal failures caused by steel,” said Glenn Woodcock, President of PSI-Polymer Systems.  “This newest iteration is a leap forward in maintenance-free sealing technology, allowing for practically any viscosity to form effective seals while avoiding the high cost and maintenance of mechanical seals.”

PSI will provide the new lip seal design for extremely low viscosity materials – but other seal options are available depending on the specific material being processed.