Hydraulic Institute launches viscosity correction standard

The Hydraulic Institute (HI) has published its new American National Standard for Effects of Liquid Viscosity on Rotodynamic (Centrifugal and Vertical) Pump Performance (ANSI/HI 9.6.7). This standard replaces HI’s more than 40-year-old viscosity correction nomographs, and is designed to predict performance changes of rotodynamic pumps operating on viscous liquids exhibiting Newtonian behavior relative to their performance on water, which is the basis for most published curves.

“By eliminating the need for interpolating graphic solutions, this standard has major technical significance and practical applications,” says Gregg Romanyshyn, HI’s technical director. “This landmark standard will provide valuable guidance to pump manufacturers, users, and others who have an interest in the performance of rotodynamic pumps.”

HI members developed the new standard along with representatives from France, Germany, Italy, Japan, and Switzerland. It also includes contributions from industry experts and veterans.

The standard covers conventional rotodynamic pumps, including open or closed impellers and single or double suction pumps. It further contains information on methodology, definitions of symbols and terms, flowcharts that outline the procedure, theoretical explanations behind the methodology, and a method for estimating net positive suction head required (NPSHR).