Impulse line blockage detector systems and methods

• US 5,680,109 A
• Filed: 06/21/1996
• Issued: 10/21/1997
• Est. Priority Date: 06/21/1996
• Status: Expired due to Term

• Current Assignee: Schneider Electric Systems USA, Inc. (Schneider Electric SE)
• Original Assignee: The Foxboro Company (Schneider Electric SE)
• Inventors: Clarke, David W., Lowe, Justin Peter
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): Wu, Daniel J.
• Application Number:
  US08/669,901
• Time in Patent Office: 487 Days
• Field of Search: 340/607-608, 340/611, 340/626, 137/554, 137/557, 73/3, 73/4 R, 364/558
• US Class Current: 340/608
• CPC Class Codes: G01F 1/34 by measuring pressure or differential pressure
• CPC Class Codes: G01L 15/00 Devices or apparatus for measuring two or more fluid pressure values simultaneously
• CPC Class Codes: G01L 27/007 Malfunction diagnosis, i.e. diagnosing a sensor defect
• CPC Class Codes: Y10T 137/8326 Fluid pressure responsive indicator, recorder or alarm

Abstract

A differential pressure sensor is attached to a process via a high and a low pressure impulse line. An absolute pressure sensor is also attached to each impulse line. To determine if an impulse line is blocked, a noise signal is acquired from the corresponding absolute pressure sensor. A variance of the noise signal is determined and compared to a threshold. If the variance is less than the threshold, an impulse line blockage is indicated.

Claims

1. A system for detecting a blockage of at least one impulse line of a differential pressure sensor, said system comprising:

an absolute pressure sensor coupled to said at least one impulse line;

a processor coupled to said absolute pressure sensor to acquire data therefrom, said processor determining a noise value as a function of said data; and

a comparator coupled to said processor to receive said noise value and compare it to a noise threshold, said comparator indicating said blockage of said at least one impulse line if said comparison fails.

2. The system of claim 1, wherein said noise value comprises a noise variance, said noise threshold comprises a variance threshold, and wherein said comparison fails if said noise variance is less than said variance threshold.

3. The system of claim 1, wherein said absolute pressure sensor comprises a first absolute pressure sensor, and said at least one impulse line comprises a first impulse line, and wherein said system further includes a second absolute pressure sensor coupled to a second impulse line of said differential pressure sensor, said processor and comparator functioning in connection with said second absolute pressure sensor to detect a blockage in said second impulse line.

4. The system of claim 1, wherein said absolute pressure sensor and said differential pressure sensor are integral with a common sensor chip.

5. The system of claim 4, wherein said absolute pressure sensor comprises a first absolute pressure sensor, said data therefrom comprises a first absolute pressure signal, and said impulse line comprises a first impulse line, said system further comprising means for combining signals from said first absolute pressure sensor and said differential pressure sensor to determine a second absolute pressure signal corresponding to a second impulse line of said at least one impulse line.

6. The system of claim 5, wherein said comparator and processor function in combination with said second absolute pressure signal to detect blockages in said second impulse line.

7. The system of claim 1, wherein said comparator is implemented in software of said processor.

8. An impulse line blockage detection system comprising:

a differential pressure sensor coupled to a high pressure impulse line and a low pressure impulse line;

a first absolute pressure sensor coupled to said high pressure impulse line;

a second absolute pressure sensor coupled to said low pressure impulse line;

a processor coupled to said first absolute pressure sensor and said second absolute pressure sensor to acquire data therefrom, said processor extracting measured noise from said data and determining a noise value for each of said first absolute pressure sensor and said second absolute pressure sensor; and

a comparator coupled to said processor to receive said noise values and compare them to noise thresholds for each of said first absolute pressure sensor and said second absolute pressure sensor, said comparator indicating a blockage of at least one of said high pressure impulse line and said low pressure impulse line if either comparison fails.

9. The system of claim 8, wherein said noise values comprise noise variances and wherein said noise thresholds comprises variance thresholds.

10. A pressure sensor-transmitter having impulse line blockage detection comprising:

a differential pressure sensor coupled to a first impulse line and a second impulse line, said differential pressure sensor being integral with a first sensor chip;

an absolute pressure sensor coupled to said first impulse line, said absolute pressure sensor being integral with said first sensor chip;

a processor coupled to said absolute pressure sensor and said differential pressure sensor to acquire data therefrom;

means for combining data from said absolute pressure sensor and said differential pressure sensor to determine absolute pressure data for said second impulse line;

means for determining a first noise value for said first impulse line from said data from said absolute pressure sensor;

means for determining a second noise value for said second impulse line from said absolute pressure data for said second impulse line; and

means for comparing each of said noise values to a noise threshold for each of said first impulse line and said second impulse line, said means for comparing indicating a blockage of at least one of said first impulse line and said second impulse line if either comparison fails.

11. The system of claim 10, wherein each of said noise values comprises a noise variance, and each of said noise thresholds comprises a threshold variance.

12. A system for detecting a blockage of an impulse line of an absolute pressure sensor, said system comprising:

a processor coupled to said absolute pressure sensor to acquire noise data therefrom, said processor determining a noise value as a function of said data; and

a comparator coupled to said processor to receive said noise value and compare it to a noise threshold, said comparator indicating said blockage of said impulse line if said comparison fails.

13. The system of claim 12, wherein said noise value comprises a noise variance and said noise threshold comprises a threshold variance.

14. A method for detecting a blockage of at least one impulse line of a differential pressure sensor, one of said at least one impulse line having an absolute pressure sensor coupled thereto, said method comprising:

acquiring data from said absolute pressure sensor;

determining a noise value as a function of said data;

comparing said noise value to a noise threshold; and

indicating said blockage of said at least one impulse line if said comparison fails.

15. The method of claim 14, wherein said noise value comprises a noise variance, said noise threshold comprises a variance threshold, and wherein said comparison fails if said noise variance is less than said variance threshold.

16. The method of claim 14, wherein said absolute pressure sensor comprises a first absolute pressure sensor, said at least one impulse line comprises a first impulse line, and a second absolute pressure sensor is coupled to a second impulse line of said differential pressure sensor, said method further including:

acquiring data from said second absolute pressure sensor;

determining a second noise value as a function of said data from said second absolute pressure sensor;

comparing said second noise value to a second noise threshold; and

indicating said blockage of said second impulse line if said comparison fails.

17. The method of claim 14, wherein said absolute pressure sensor and said differential pressure sensor are integral with a common chip.

18. The method of claim 17, wherein said absolute pressure sensor comprises a first absolute pressure sensor, said data therefrom comprises a first absolute pressure signal, and said impulse line comprises a first impulse line, said method further comprising combining signals from said first absolute pressure sensor and said differential pressure sensor to determine a second absolute pressure signal corresponding to a second impulse line of said at least one impulse line.

19. The method of claim 18, wherein said method further includes:

determining a second noise value as a function of said second absolute pressure sensor signal;

comparing said second noise value to a second noise threshold; and

indicating said blockage of said second impulse line if said comparison fails.

20. A blockage detection method for detecting blockages in at least one of a high pressure impulse line and a low pressure impulse line, each coupled to a differential pressure sensor, said high pressure impulse line being coupled to a first absolute pressure sensor and said low pressure impulse line being coupled to a second absolute pressure sensor, said method comprising:

acquiring data from said first absolute pressure sensor and said second absolute pressure sensor

extracting measured noise from said data and determining a noise value for each of said first absolute pressure sensor and said second absolute pressure sensor;

comparing each noise value to a separate threshold; and

indicating a blockage of at least one of said high pressure impulse line and said low pressure impulse line if either comparison fails.

21. The method of claim 20, wherein said noise values comprise noise variances and wherein said noise thresholds comprise variance thresholds.

22. An blockage detection method for a pressure sensor comprising:

acquiring data from said pressure sensor, said pressure sensor include a differential pressure sensor coupled to a first impulse line and a second impulse line, said pressure sensor further including an absolute pressure sensor coupled to said first impulse line, said differential pressure sensor and said absolute pressure sensor being integral with a same chip;

combining data from said absolute pressure sensor and said differential pressure sensor to determine absolute pressure data for said second impulse line;

determining a first noise value for said first impulse line from said data from said absolute pressure sensor;

determining a second noise value for said second impulse line from said absolute pressure data for said second impulse line; and

comparing each of said noise values to a separate noise threshold, said comparing indicating a blockage of at least one of said first impulse line and said second impulse line if either comparison fails.

23. The method of claim 22, wherein each of said noise values comprises a noise variance, and each of said noise thresholds comprises a threshold variance.

24. A method for detecting a blockage of an impulse line of an absolute pressure sensor, said method comprising:

acquiring noise data from said absolute pressure sensor;

determining a noise value as a function of said data;

comparing said noise value to a noise threshold; and

indicating said blockage of said impulse line if said comparison fails.

25. The method of claim 24, wherein said noise value comprises a noise variance and said noise threshold comprises a threshold variance.