On-site analyzer

• US 20020185604A1
• Filed: 07/22/2002
• Published: 12/12/2002
• Est. Priority Date: 08/14/1998
• Status: Active Grant

• Current Assignee: Spectro Scientific, Inc.
• Original Assignee: On-Site Analysis, Inc. (Spectro Scientific, Inc.)
• Inventors: Rosenbaum, Neil, Abuneaj, Yosef, Coates, John
• Granted Patent: US 6,707,043 B2
• Time in Patent Office: Days
• US Class Current: 250/339.09
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/443 Emission spectrometry
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/3577 for analysing liquids, e.g. polluted water
• CPC Class Codes: G01N 21/67 using electric arcs or discharges
• CPC Class Codes: G01N 21/69 specially adapted for fluids , e.g. molten metal
• CPC Class Codes: G01N 33/2847 Water in oil basic sediment and water G01N33/2823; oil in water G01N33/1833
• CPC Class Codes: G01N 33/2858 metal particles
• CPC Class Codes: G01N 33/2888 Lubricating oil characteristics, e.g. deterioration lubricating properties G01N33/30
• CPC Class Codes: G01N 33/30 for lubricating properties

Abstract

An apparatus (10) for analyzing lubricant oils and functional fluids includes an optical emission spectrometer (OES) (26) having a substantially continuously valued wavelength versus intensity output (140). The OES (26) analyzes light captured from a spark emission stand (58) through which the fluid sample is flowed. An expert system (160-172) operates according to a set of Rules, and generates diagnostic text (174) for an operator based on the information about the fluid sample provided by the OES (26) and other measurement devices. The apparatus (10) is reduce in size, weight and cost.

Claims

1. An apparatus for analyzing a fluid sample to determine constituents thereof comprising:

a housing;

a transfer assembly having an inlet configured to receive the fluid sample, said transfer assembly being configured to selectively flow the fluid sample to an outlet thereof;

an infrared (IR) spectral analyzer assembly disposed in said housing and coupled to said outlet, said IR spectral analyzer assembly being configured to analyze the fluid sample and generate a first data set;

an optical emission spectrometer (OES) assembly disposed in said housing and coupled to said outlet, said OES assembly being configured to analyze the fluid sample and generate a second data set substantially continuously valued over at least a first predetermined wavelength range;

a controller connected to said transfer assembly, said IR spectral assembly, and said OES assembly and configured to control the operation of said apparatus in accordance with a predetermined operating strategy, said controller being configured to determine constituents of the fluid sample in accordance with said first and second data sets.

2. The apparatus of claim 1 further including:

a viscometer disposed in said housing and coupled to said outlet, said viscometer being configured to analyze the fluid sample and generate a third data set.

3. The apparatus of claim 1 wherein said IR spectral analyzer assembly includes:

an IR source configured to generate an IR radiation beam focused along a principal axis to converge;

a detector assembly spaced apart from said IR source; and

,

a flow cell assembly including a sample cell and a compensator cell, said flow cell assembly being slidably movable along a motion axis transverse of said principal axis between a first position wherein said compensator cell is optically intermediate said IR source and said detector and a second position wherein said sample cell is optically intermediate said IR source and said detector;

wherein said compensator cell and said sample cell are each arranged such that a respective normal axis associated therewith defines a predetermined tilt angle relative to said principal axis, said compensator cell and said sample cell each having a respective effective thickness and index of refraction that are substantially equal.

6. The apparatus of claim 1 wherein said OES assembly includes:

a fluid sample excitation assembly configured to excite the fluid sample to spectroemissive levels to thereby generate radiation characteristic of said constituents;

a first spectrometer configured to receive said radiation and generate a first spectral pattern;

a second spectrometer configured to receive said radiation and generate a second spectral pattern different from said first spectral pattern,

wherein said second data set comprises said first spectral pattern and said second spectral pattern.

7. The apparatus of claim 6 wherein said OES assembly further includes:

means for controlling said first and second spectrometers to generate said first and second spectral patterns substantially simultaneously.

8. The apparatus of claim 6 wherein said first spectrometer has a first resolution associated therewith and said second spectrometer has a second resolution associated therewith that is less than said first resolution.

9. The apparatus of claim 1 wherein said fluid sample comprises one of a lubricating oil and functional fluid and said controller determines said constituents with respect to type and concentration parameters, said controller further including:

means responsive to said type and concentration parameters for diagnosing said one of said lubricating oil and functional fluid and generating an output.

10. The apparatus of claim 9 wherein said output includes information indicative of an operational state of equipment from which said sample was drawn.

4. The apparatus of claim 4 wherein said sample cell comprises zinc selenide material.

5. The apparatus of claim 4 wherein said controller includes:

means for moving said flow cell assembly to said first position and for generating a background absorption pattern;

means for flowing the fluid sample through said sample cell; and

,

means for moving said flow cell assembly to said second position and for generating a sample absorption pattern.

11. A sample flow cell assembly for an infrared (IR) spectral analyzer comprising:

a body having a first bore and a second bore;

a sample cell disposed in said first bore and including an inlet and an outlet for sample fluid flow therethrough, said sample cell including a first normal axis associated therewith; and

,

a compensator window disposed in said second bore, said compensator window including a second normal axis associated therewith;

said compensator window and said sample cell each being arranged such that said first and second normal axes define a predetermined tilt angle relative to a principal axis along which an IR source generates an IR radiation beam, said compensator window and said sample cell each having a respective effective thickness and index of refraction that are substantially equal.

12. The apparatus of claim 11 wherein said sample cell comprises zinc selenide material.

14. The method of claim 13 wherein the sample spectrum comprises an array of values representative of wavelengths and spectral intensities associated therewith over a spectral range, wherein said plurality of spectral features are defined by corresponding emission lines, and wherein step (B) is performed by the substep of:

selecting a plurality of emission lines from the background spectrum wherein each selected emission line has a respective predetermined wavelength value associated therewith.

15. The method of claim 14 wherein step (C) is performed by the substeps of:

identifying the plurality of selected background emission lines in the array of values; and

,

determining a respective measured wavelength value of the identified emission lines in the array.

16. The method of claim 15 wherein step (D) is performed by the substeps of:

determining a respective wavelength offset between the predetermined wavelength values and the measured wavelength values;

converting the wavelength offsets into a composite wavelength offset for the sample spectrum;

determining a pixel shift number as a function of the composite wavelength offset; and

,

shifting the spectral intensities of the array of values by the pixel shift number to thereby regularize the sample spectrum with respect to wavelength.

17. The method of claim 13 wherein the fluid sample comprises one of used lubricating oil and used functional fluid, and step (A) includes the substeps of:

exciting a new sample of said one of lubricating oil and functional fluid corresponding in type and grade to the used sample to spectroemissive levels to thereby generate radiation;

acquiring a background spectrum responsive to the radiation; and

,

storing the background spectrum for subsequent use.

19. The method of claim 18 wherein the fluid sample contains constituents, and wherein step (A) is performed by the substeps of:

identifying an emission line associated with at least one constituent;

selecting a first set of spectral features from the plurality of spectral features of the background spectrum;

obtaining a predetermined number of spectra of the fluid sample using the pair of electrodes;

determining a first intensity variation of said identified emission line over said predetermined number of spectra;

determining, for each spectral feature in said first set, a respective second intensity variation over said predetermined number of spectra;

selecting spectral features from said first set that have a respective second intensity variation that is less than said first intensity variation to thereby form a second set of spectral features;

selecting one of the spectral features from said second set based on predetermined criteria.

20. The method of claim 19 wherein determining a respective second intensity variation step comprises the substeps of:

dividing, for each one of said predetermined number of spectra, the intensity of the identified emission line of the constituent by the intensity of the respective background spectral feature in the first set to thereby produce ratio values; and

,

calculating said second intensity variation using said ratio values.

21. The method of claim 19 wherein step (B) includes the substeps of:

measuring the intensity of the background spectral feature in the sample spectrum; and

,

ratioing at least a portion of the intensity of the sample spectrum by the measured intensity of the background spectral feature.

22. The method of claim 21 wherein the electrodes comprise silver material and the background spectral feature comprises a 336 nm silver emission line, and the measured intensity comprises area under a curve associated with the 336 nm silver line.

24. The method of claim 23 wherein step (D) further includes the substep of:

subtracting a reference spectrum from the sample spectrum.

25. The method of claim 23 wherein the sample spectrum comprises an n-row array of values representative of wavelengths and spectral intensities associated therewith over a spectral range where n corresponds to a number of pixels of an imaging device in the spectrometer, and wherein step (A) is performed by the substeps of:

selecting multiple emission lines from the plurality of spectral features of the background spectrum wherein each emission line has a predetermined known, wavelength value;

determining a respective measured wavelength value for the multiple emission lines in the array of values;

determining a respective wavelength offset between the predetermined known wavelength values and the measured wavelength values, for each selected emission line;

determining a pixel shift number as a function of the wavelength offsets; and

,

shifting the spectral intensifies in the array by the pixel shift number.

26. The method of claim 25 further including the steps of:

evaluating a plurality of rules in response to the constituent concentration parameter and producing a plurality of output signals; and

,

determining a condition of a component of equipment from which the sample was drawn as a function of said output signals.

13. A method of regularizing a sample spectrum of a fluid sample generated by a spectrometer having a pair of electrodes, the method comprising the steps of:

(A) defining a background spectrum having a plurality of spectral features indicative at least in part of the composition of the electrodes;

(B) selecting at least a first background spectral feature from said plurality of spectral features wherein the first background spectral feature has a predetermined wavelength value associated therewith;

(C) determining a measured wavelength value of the at least first background spectral feature in the sample spectrum; and

,

(D) translating the sample spectrum with respect to wavelength in accordance with said predetermined wavelength value, said measured wavelength value, and a predetermined translation strategy.

18. A method of normalizing an intensity of a sample spectrum of a fluid sample by a spectrometer having a pair of electrodes, the method comprising the steps of:

(A) selecting a background spectral feature from a plurality of spectral features of a background spectrum that is indicative at least in part of the composition of the electrodes wherein the background spectral feature has an intensity variation characteristic; and

,

(B) transforming the sample spectrum with respect to intensity in accordance with an intensity of said selected background spectral feature as indicated in the sample spectrum.

23. A method of analyzing a sample spectrum of one of lubricating oil sample and a functional fluid sample having one or more constituent elements wherein the sample spectrum is generated by a spectrometer having a pair of electrodes, the method comprising the steps of:

(A) translating the sample spectrum with respect to wavelength in accordance with a first background spectral feature having a known wavelength selected from a background spectrum having a plurality of spectral features indicative at least in part of the composition of the electrodes;

(B) determining an intensity of a second background spectral feature having an intensity variation characteristic;

(C) determining an intensity of a characteristic emission line associated with at least one of the constituent elements;

(D) transforming the constituent element intensity into a concentration parameter using (i) the intensity of the second background spectral feature in the sample spectrum, (ii) the intensity of the constituent emission line, and (iii) predetermined data.