Low-flow pump-off control
First Claim
1. A low-flow pump-off control device for deactivating a motor for a pump during conditions when a rate of supply of a source of fluid to be pumped by said pump is insufficient, said device comprising:
- a pipe section having an inlet and an outlet, said inlet being connectable to said source of fluid to be pumped through said pipe section;
a plurality of plates disposed in said pipe section, each of said plates respectively defining at least one orifice through which said fluid is caused to pass;
a differential pressure switch for sensing a differential pressure between a pressure upstream of a first one of said plates and a pressure downstream of a last one of said plates that is at or below a set point indicative of a predetermined low flow rate of said liquid;
a first timer in communication with said switch for accumulating periods of time at which said switch senses said differential pressure;
a motor activation and deactivation means in communication with said timer for deactivating said motor when said accumulated periods of time total a predetermined amount; and
a second timer in communication with said first timer which is activated when said accumulated periods of time total said predetermined amount, wherein said motor activation and deactivation means is in communication with said second timer and activates said motor when said second timer times a second predetermined amount of time.
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Accused Products
Abstract
A low-flow pump-off control device for deactivating a motor for a pump during conditions when a rate of supply of a source of fluid to be pumped by the pump is insufficient includes: a pipe section having an inlet and an outlet, the inlet being connectable to the source of fluid to be pumped through the pipe section; a plurality of plates disposed substantially perpendicularly in the pipe section, each of the plates defining at least one orifice through which the fluid is caused to pass; a differential pressure switch for sensing a differential pressure between a pressure upstream of a first one of the plates and a pressure downstream of a last one of the plates that is at or below a set point indicative of a predetermined low flow rate of the liquid; a first timer in communication with the switch for accumulating periods of time at which the switch senses the differential pressure; a motor activation and deactivation relay in communication with the timer for deactivating the motor when the accumulated periods of time total a predetermined amount; and a second timer in communication with the first timer which is activated when the accumulated periods of time total the predetermined amount, wherein the motor activation and deactivation relay is in communication with the second timer and activates the motor when the second timer times a second predetermined amount of time.
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Citations
11 Claims
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1. A low-flow pump-off control device for deactivating a motor for a pump during conditions when a rate of supply of a source of fluid to be pumped by said pump is insufficient, said device comprising:
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a pipe section having an inlet and an outlet, said inlet being connectable to said source of fluid to be pumped through said pipe section; a plurality of plates disposed in said pipe section, each of said plates respectively defining at least one orifice through which said fluid is caused to pass; a differential pressure switch for sensing a differential pressure between a pressure upstream of a first one of said plates and a pressure downstream of a last one of said plates that is at or below a set point indicative of a predetermined low flow rate of said liquid; a first timer in communication with said switch for accumulating periods of time at which said switch senses said differential pressure; a motor activation and deactivation means in communication with said timer for deactivating said motor when said accumulated periods of time total a predetermined amount; and a second timer in communication with said first timer which is activated when said accumulated periods of time total said predetermined amount, wherein said motor activation and deactivation means is in communication with said second timer and activates said motor when said second timer times a second predetermined amount of time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for deactivating a motor for a pump during conditions when a rate of supply of a source of fluid to be pumped by said pump is insufficient, the method comprising the steps of:
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providing a low-flow pump-off control device comprising a pipe section having an inlet and an outlet, said inlet being connectable to said source of fluid to be pumped through said pipe section, a plurality of plates disposed in said pipe section, each of said plates respectively defining at least one orifice through which said fluid is caused to pass, and a differential pressure switch in communication with said pipe section upstream of a first one of said plates and downstream of a last one of said plates; selecting a differential pressure between a pressure upstream of said first one of said plates and a pressure downstream of said last one of said plates that corresponds to the upper limit of an insufficient flow rate to said pump; supplying said differential pressure switch with a set point equal to said differential pressure; accumulating periods of time at which said switch senses a differential pressure at or below said set point; deactivating said motor when said accumulated periods of time total a first predetermined amount of time; and reactivating said motor when a second predetermined amount of time elapses following the time at which said motor is deactivated.
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Specification