Patent ID: 8303260

Claim:
A method for controlling the operation of a pump, including a centrifugal pump, centrifugal mixer, centrifugal blower or centrifugal compressor, comprising: determining an actual flow value without using a flow or pressure sensor based at least partly on a comparison of speed and power sensed in relation to the current operation of the pump and information contained in a calibrated curve of speed versus closed valve power together with published pump performance data, including best efficiency power, closed valve power and best efficiency flow at rated pump speed; determining a corrected threshold flow value based at least partly on a flow value associated with an unfavorable operating condition of the pump and corrected based on a relationship between a current operating speed of the pump and a rated operating speed of the pump; and controlling the operation of the pump based at least partly on a comparison between the actual flow value and the corrected threshold flow value in order to provide pump protection for the pump.