Methods and devices for determination of flow reservoir volume

1. A flow metering system, comprising:

a cavity;

an actuation shaft disposed in the cavity and movable between a first position within the cavity and a second position within the cavity;

an input conduit fluidly connectable to a flow material reservoir, the input conduit in fluid communication with a proximal flow space defined by the cavity when the actuation shaft is in both the first position and the second position;

a flow metering device chamber in fluid communication with the input conduit through the proximal flow space when the actuation shaft is in the first position for filling the flow metering device chamber with flow material from the flow material reservoir and not in fluid communication with the input conduit when the actuation shaft is in the second position;

an output conduit adapted to dispense flow material from the flow metering device chamber when the actuation shaft is in the second position; and

a sensor adapted to obtain data for determining a backstroke volume of flow material from the proximal flow space into the flow material reservoir when the actuation shaft is moved from the first position that fills the flow metering device chamber with flow material to the second position that dispenses the flow material from the flow metering device chamber through the output conduit.

2. The flow metering system of claim 1 , wherein the flow material reservoir comprises a first chamber holding the flow material and a second chamber holding a gas and the sensor.

3. The flow metering system of claim 1 , wherein the sensor is a pressure sensor.

4. The flow metering system of claim 1 , further comprising a pump that houses the flow material reservoir and the sensor.

5. The flow metering system of claim 4 , wherein the pump includes a user interface and a processor adapted to control movement of the actuation shaft and determine the change in volume based on the data acquired by the sensor.

6. The flow metering system of claim 5 , wherein the processor is adapted to control the sensor to acquire data before positioning the actuation shaft in the second position and after positioning the actuation shaft in the second position.

7. The flow metering system of claim 5 , wherein the processor is adapted to determine the difference between a volume of the flow material in the flow material reservoir before positioning the actuation shaft in the second position and a volume of the flow material in the flow material reservoir after positioning the actuation shaft in the second position.

8. The flow metering system of claim 5 , wherein the processor is adapted to determine the backstroke volume from the data acquired by the sensor each time the actuation shaft is moved from the first position to the second position, and wherein the processor is adapted to stop movement of the actuation shaft if a first determined backstroke volume is not substantially the same as a second backstroke volume.

9. The flow metering system of claim 5 , wherein the processor is adapted to determine the backstroke volume from the data acquired by the sensor each time the actuation shaft is moved from the first position to the second position, and wherein the processor is adapted to indicate an error state on the user interface if a first determined backstroke volume is not about equal to a second backstroke volume.

10. A flow metering system, comprising:

a cavity defining a proximal flow space;

an actuation shaft disposed in the cavity;

a flow metering device chamber;

a sensor; and

a computer processor, the computer processor adapted to:

position the actuation shaft in a first position in the cavity such that the flow metering device chamber is in fluid communication with the cavity;

cause an aliquot of flow material to flow into the flow metering device chamber from a flow material reservoir through an input conduit and the proximal flow space;

position the actuation shaft in a second position in the cavity to dispense the flow material from the flow metering device chamber out an output conduit with the flow material reservoir in fluid communication with the proximal flow space such that positioning of the actuation shaft to the second position causes a backstroke volume of flow material to flow from the proximal flow space into the flow material reservoir;

observe a change in volume of the flow material in the flow material reservoir after the actuation shaft is moved to the second position with data gathered from the sensor; and

determine the backstroke volume from the data.

11. The flow metering system of claim 10 , where the processor is adapted to gather data with the sensor before positioning the actuation shaft in the second position and after positioning the actuation shaft in the second position.

12. The flow metering system of claim 10 , wherein the processor is adapted to determine the backstroke volume by measuring a difference of a volume of flow material in the flow material reservoir before positioning the actuation shaft in the second position and a volume of the flow material in the flow material reservoir after positioning the actuation shaft in the second position.

13. The flow metering system of claim 10 , further comprising the flow material reservoir, the flow material reservoir comprising a first chamber holding the flow material and a second chamber holding a gas and the sensor.

14. The flow metering system of claim 10 , wherein the sensor is a pressure sensor.

15. The flow metering system of claim 10 , wherein the processor is further adapted to stop actuation of the actuation shaft if a first determined backstroke volume is not substantially the same as a second backstroke volume.

16. The flow metering system of claim 10 , wherein the processor is further adapted to trigger an error state if a first determined backstroke volume is not about equal to a second backstroke volume.

17. The flow metering system of claim 10 , further comprising a pump that houses the flow material reservoir and the sensor.