8 - Pump Mechanical Seal Flush Best Practices

Abstract

This chapter presents best practices for pump mechanical seals in the hope that these proven best practices significantly increase plant's mechanical seal and pump mean time between failures (MTBFs). It is well known that pump mechanical seal MTBF is the lowest of all machinery components. Mechanical seals are typically categorized into two major types; pusher and non-pusher. A pusher-type seal consists of a primary sealing ring assembled with an “O” ring and springs (can be one or multiple). The purpose of this is to force the sealing fluid across the face and keep it from leaking to the ID (atmospheric) side of the seal. A non-pusher type seal consists of a bellows assembly. The bellows is a component that acts as both the load element (like a spring in a pusher type) and a secondary sealing element.