Automatic low fluid shut-off method for a pumping system
First Claim
1. In a continuous flow pumping system having a pump in fluid communication with a tank of liquid and adapted to transfer the liquid out of the tank, and a pump controller in communication with the pump, a method of automatically stopping the pump when the tank is empty comprising the steps of:
- sampling, by the pump controller, of a pump parameter value after an initial pump start-up time interval;
calculating whether there is any percentage change in said pump parameter value once every predetermined sampling time interval relative to an average of pump parameter values taken over a predetermined average time interval;
comparing said percentage change of said pump parameter value to a predetermined pump parameter value percentage change; and
stopping the pump when said percentage change of said pump parameter value is greater than said predetermined pump parameter value percentage change.
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Accused Products
Abstract
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.
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Citations
20 Claims
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1. In a continuous flow pumping system having a pump in fluid communication with a tank of liquid and adapted to transfer the liquid out of the tank, and a pump controller in communication with the pump, a method of automatically stopping the pump when the tank is empty comprising the steps of:
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sampling, by the pump controller, of a pump parameter value after an initial pump start-up time interval; calculating whether there is any percentage change in said pump parameter value once every predetermined sampling time interval relative to an average of pump parameter values taken over a predetermined average time interval; comparing said percentage change of said pump parameter value to a predetermined pump parameter value percentage change; and stopping the pump when said percentage change of said pump parameter value is greater than said predetermined pump parameter value percentage change. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a continuous flow pumping system having a pump in fluid communication with a container of liquid and adapted to transfer the liquid out of the container, a flowmeter downstream of the pump, and a pump controller in communication with the pump and the flowmeter, a method of automatically stopping the pump when the container of liquid is empty, the method comprising:
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monitoring a flow rate of liquid through the flowmeter after an initial predetermined pump start-up time period; calculating any percentage change in flow rate over a previous average flow rate; comparing said percentage change in flow rate to a predetermined flow rate percentage change; and stopping the pump when said percentage change in flow rate is greater than said predetermined flow rate percentage change. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method of automatically shutting off a continuous flow type pump in a continuous flow pumping system having the pump in fluid communication with a container of liquid when the container of liquid is empty, the pumping system further including a nutating disk type flowmeter with a pulse generator in fluid communication with and downstream of the pump, and a programmable pump controller in electrical communication with the flowmeter and the pump, the method comprising the steps of:
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waiting a minimum pump flow time upon pump startup; counting the electrical pulses from the flowmeter during a predetermined time interval to determine a pulse frequency; calculating an average pulse frequency over a predetermined number of said predetermined time intervals; calculating a percentage change in pulse frequency relative to said average pulse frequency; comparing said percentage change in pulse frequency to a predetermined percentage change value; and stopping the pump when said percentage change in pulse frequency is greater than said predetermined percentage change value. - View Dependent Claims (15, 16, 17)
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- 18. An apparatus for automatically shutting off a pump in a continuous flow pumping system having the pump in fluid communication with a container of liquid, a flowmeter in fluid communication with and downstream of the pump, and a programmable pump controller in communication with the pump and the flowmeter, the apparatus characterized by the flowmeter having a pulse generator providing electrical pulses, the frequency of which correlates to a flow rate of liquid therethrough, the pump controller including a microcontroller configurable to be enabled into an automatic low fluid shutoff mode wherein the frequency of electrical pulses from the flowmeter is monitored and a percentage change in frequency is calculated at a predetermined time interval to an average frequency calculated relative to a predetermined number of predetermined time intervals and if the percentage change in frequency is greater than a selectable percentage change, the pump controller shuts off the pump.
Specification