Pump ripple pressure monitoring for incompressible fluid systems

1. A method of monitoring performance of an incompressible fluid system, the incompressible fluid system having a positive displacement pump and a pressure sensor, the method comprising:

sensing a pressure of the fluid with the pressure sensor;

determining from the pressure sensing a ripple frequency of the fluid and a speed of the positive displacement pump;

calculating from the speed of the positive displacement pump a flow rate of the fluid induced by the positive displacement pump;

determining, based on the calculated flow rate and the sensed pressure, a flow restriction of the fluid system; and

assessing the fluid system for an excessive flow restriction condition using the determined flow restriction.

2. The method of claim 1 wherein the step of assessing the fluid system for an excessive flow restriction condition using the determined flow restriction comprises:

calculating an average fluid pressure over a period of time based on the sensed fluid pressures;

comparing the calculated average fluid pressure to a fluid pressure sensed at a specific time; and

indicating an excessive flow restriction when the fluid pressure sensed at a specific time deviates from the calculated average fluid pressure by greater than a threshold magnitude.

3. The method of claim 1 wherein the pressure sensor is disposed at a discharge of the positive displacement pump.

4. The method of claim 1 wherein the step of assessing the fluid system for an excessive flow restriction condition using the determined flow restriction comprises:

comparing the determined flow restriction of the fluid system to a baseline flow restriction; and

indicating an excessive flow restriction when the determined flow restriction exceeds the baseline flow restriction by a first predetermined amount.

5. The method of claim 4 further comprising:

providing an indication to an operator of the fluid system to inspect a filter of the fluid system when the determined flow restriction exceeds the baseline flow restriction by a second predetermined amount.

6. The method of claim 1 further comprising:

developing a pressure trendline from the sensed pressures collected in the step of sensing a pressure of the fluid with the pressure sensor; and

evaluating the pressure trendline to determine a degree of flow restriction in the fluid system.

7. The method of claim 6 further comprising:

evaluating the pressure trendline to determine whether the positive displacement pump has failed.

8. The method of claim 1 wherein said positive displacement pump is coupled to a rotatable prime mover, the method further comprising:

determining, from the speed of the positive displacement pump, the speed of the rotatable prime mover.

9. The method of claim 8 further comprising comparing the speed of the rotatable prime mover to an output of another sensor that measures the speed of the rotatable prime mover.

10. A method of monitoring a performance of an incompressible fluid system using a single sensor disposed in the fluid system, the fluid system comprising a positive displacement pump coupled to fluid conduit and driven by a prime mover, the single sensor comprising a pressure sensor for sensing the pressure of a fluid passing through the fluid conduit, the method comprising:

sensing a pressure of the fluid with the pressure sensor for a period of time;

determining from the pressure sensing a ripple frequency of the fluid and a speed of the positive displacement pump;

checking, using the ripple frequency of the fluid, for failure of a pump driver coupling the positive displacement pump to the prime mover;

deriving the speed of the prime mover from the speed of the positive displacement pump and comparing the derived speed to a measured speed of the prime mover; and

evaluating the fluid system for an excessive flow restriction condition by:

calculating from the speed of the positive displacement pump a flow rate of the fluid induced by the positive displacement pump;

determining, based on the calculated flow rate and the sensed pressure, a flow restriction of the fluid system;

comparing the determined flow restriction of the fluid system to a baseline flow restriction; and

indicating an excessive flow restriction when the determined flow restriction exceeds the baseline flow restriction by a first predetermined amount.

11. The method of claim 10 wherein the baseline flow restriction is a calculated average flow restriction over a period of time.

12. The method of claim 10 further comprising:

providing an indication to an operator of the fluid system to inspect a filter of the fluid system when the determined flow restriction exceeds the baseline flow restriction by a second predetermined amount.

13. The method of claim 10 further comprising:

developing a pressure trendline from the sensed fluid pressures collected in the step of sensing a pressure of the fluid system with the pressure sensor; and

evaluating the pressure trendline to determine a degree of flow restriction in the fluid system.

14. The method of claim 10 further comprising:

developing a pressure trendline from the sensed fluid pressures collected in the step of sensing a pressure of the fluid system with the pressure sensor; and

evaluating the pressure trendline to determine leakage of the positive displacement pump.

15. The method of claim 10 further comprising:

creating first logged data comprising sensed pressure, ripple frequency, speed of the positive displacement pump, and flow rate determined for a first time;

creating second logged data comprising sensed pressure, ripple frequency, speed of the positive displacement pump, and flow rate determined for a second time;

comparing said second logged data to said first logged data to determine leakage of the positive displacement pump.

16. The method of claim 10 further comprising:

evaluating the fluid system for resonances based on pressure ripple.

17. A method of monitoring deterioration of a positive displacement pump, the positive displacement pump included in an incompressible fluid system, the incompressible fluid system further comprising a pressure sensor positioned to sense a pressure of fluid exiting the positive displacement pump, the method comprising:

sensing a pressure of the fluid with the pressure sensor at a first time;

determining from the sensed pressure a ripple frequency of the fluid and speed of the positive displacement pump at the first time;

calculating from the speed of the positive displacement pump a flow rate of the fluid at the first time;

creating first logged data by saving to a memory the sensed pressure, ripple frequency, speed of the positive displacement pump, and flow rate determined at the first time;

repeating the steps of sensing pressure, determining ripple frequency and speed of the positive displacement pump, and calculating flow rate for a second time; and

creating second logged data by saving to a memory the sensed pressure, ripple frequency, speed of the positive displacement pump, and flow rate determined at the second time.

18. The method of claim 17 further comprising:

comparing the second logged data to the first logged data to determine leakage of the positive displacement pump; and

providing an indication to an operator of the fluid system when the determined leakage of the positive displacement pump exceeds a predetermined amount.

19. The method of claim 17 further comprising:

developing a pressure trendline from the sensed pressures of the first and second logged data; and

evaluating the pressure trendline to determine a degree of flow restriction in the fluid system.

20. The method of claim 19 further comprising:

evaluating the pressure trendline to determine whether the positive displacement pump has failed.