Understanding Uncertainties in Viscous Performance Predictions for Centrifugal Pumps

Scott Lang, Applied Flow Technology, USA; Hemanth Satish, PE, US Gas Operations – Reliability TC Energy, Canada; Stefan Berten, PhD, Head Global Core Technology Hydraulics, Sulzer Management Ltd, Switzerland; Presented at the Virtual Turbomachinery & Pump Symposia, December 2020

Abstract: 

Accurate predictions of centrifugal pump performance are critical in every fluid industry. Many industries encounter situations where a fluid more viscous than water must be conveyed with a centrifugal pump. As liquid viscosity increases, losses in the pump increase and degrade its performance. Pumps are nearly always tested only with pure water, meaning some estimation of this performance degradation must be made for pump and motor selection. There are several ways to make this estimation, all of which carry uncertainty. A widely adopted method is described in ANSI/HI 9.6.7-2015 – Rotodynamic Pumps – Guideline for Effects of Liquid Viscosity on Performance. Proper application and understanding of the uncertainties in HI 9.6.7-2015 are described here. The analysis herein shows that recent test data falls within reasonable uncertainty levels, and recommendations for pump and motor sizing accounting for these uncertainties are given. Finally, the HI 9.6.7-2015 method correlations are based on trustworthy but limited data – a plea to the industry is made to provide the Hydraulic Institute with additional viscous pump measurements for the purposes of continually improving these correlations.