The Role Of Hydraulic Balance In Mechanical Pump Seals

Abstract

The mechanical seal is the least reliable component in centrifugal pumps. Most seals fail prematurely, i.e., before the seal face wears out. One cause of premature failure is face instability when the seal geometric balance ratio is too low. In this study, forces on the seal are reviewed to define seal balance ratio and pressure gradient factor. These terms are arranged to show that balanced seal faces may separate before wearing out. Unbalanced seals are not subject to this type of separation. This potential instability of balanced seals is a significant factor in reducing seal reliability. The limitations for seal face loading show that unbalanced seals are suitable for most services.