Improving performance for pumps handling high viscosity fluids

The label "high viscosity fluids" can be applied to an incredible range of liquids. providing a seal system to fit this varying range of fluids has po sed a dilemma to plant maintenance engineers. Because viscosity directly re lates to temperature, a single pump in a, batch process can encounter a bro ad spectrum of viscosity. Improper application of a scaling system can lead to unacceptable seal life or a packing which leaks valuable product to the atmosphere. In a niche where mechanical seats provide one solution, and me chanical packing another, mechanical lip seals satisfy a middle ground that has previously been scarcely found. This paper examines the differences between three sealing solutions on typi cal chemical process pumps. The discussion will include design concepts tha t demonstrate the theories of mechanical lip seals manifested in improved p roperties present at sealing surface areas. Use of case studies as well as test data illustrates the performance of polytetrafluoroethylene (PTFE) in high viscosity situations. The investigation of temperature gradients, leak age rates, and cost profiles is aimed at finding the optimal sealing soluti on.