American Petroleum Institute (API) and Hydraulic Institute (HI) - Pump Preferred Operating Range (POR) - API 610 and ANSI/HI 9.6.3-2017
The API 610 and ANSI/HI 9.6.3-2017 standards are recommended guidelines and not mandatory
API 610: for Rotodynamic (centrifugal and vertical) pumps for Petroleum, Petrochemical and Natural Gas Industries
ANSI/HI 9.6.3-2017: Guideline for Operating Regions