Automatic low fluid shut-off method for a pumping system

摘要

A method and apparatus for automatically shutting off a dispensing device when the fluid source tank is empty includes a programmed pump controller in communication with the dispensing device and a flowmeter having a pulse generator. Upon startup of the dispensing device, the controller waits for an initial time period, then periodically determines the pulse frequency which correlates to a rate of fluid flow. The pulse frequency is compared to a calculated average pulse frequency and, if the pulse frequency has changed a pre-selected, pre-determined amount or percentage when compared to the average pulse frequency the dispensing device is shut-off. The change in pulse frequency indicates ingestion of air into the pumping system meaning an empty source tank.