PT07 - Application Considerations for Mechanical Seals in Variable Speed Pumps

Abstract

Variable speed pumps are being used more frequently to improve the efficiency and operational flexibility of centrifugal pumps. Operating pumps over a range of speeds can allow the end user to tailor the pump output in real time to meet the changing demands of the process. The mechanical seals in these pumps, however, are often overlooked or evaluated at only the highest operating speed. The range of operating conditions can impact the seal performance and the requirements of the mechanical seal piping plans. It is important for end users, pump OEMs, and even seal OEMs to understand how to evaluate mechanical seals in variable speed pumps. This should include the impact of not only the actual speeds but also the pressures, temperatures and flow rates through the sealing system. Other factors such as the pump and impeller construction can impact the seal operating conditions and performance.