NL1040884C2 - Method and device for an optical sensor for measuring the composition of a liquid. - Google Patents

Method and device for an optical sensor for measuring the composition of a liquid. Download PDF

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Publication number
NL1040884C2
NL1040884C2 NL1040884A NL1040884A NL1040884C2 NL 1040884 C2 NL1040884 C2 NL 1040884C2 NL 1040884 A NL1040884 A NL 1040884A NL 1040884 A NL1040884 A NL 1040884A NL 1040884 C2 NL1040884 C2 NL 1040884C2
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NL
Netherlands
Prior art keywords
light
sensor
preceding
liquid
measuring
Prior art date
Application number
NL1040884A
Other languages
Dutch (nl)
Inventor
Frank Akkerman
Mateo Jozef Jacques Mayer
Original Assignee
Easymeasure
Handelsonderneming F Akkerman
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Priority to NL1040648 priority Critical
Priority to NL1040648 priority
Application filed by Easymeasure, Handelsonderneming F Akkerman filed Critical Easymeasure
Priority to NL1040884 priority
Priority to NL1040884A priority patent/NL1040884C2/en
Application granted granted Critical
Publication of NL1040884C2 publication Critical patent/NL1040884C2/en

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/01Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03Cuvette constructions
    • G01N21/05Flow-through cuvettes
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/01Arrangements or apparatus for facilitating the optical investigation
    • G01N21/15Preventing contamination of the components of the optical system or obstruction of the light path
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/314Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47Scattering, i.e. diffuse reflection
    • G01N21/49Scattering, i.e. diffuse reflection within a body or fluid
    • G01N21/53Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
    • G01N21/532Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke with measurement of scattering and transmission
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/84Systems specially adapted for particular applications
    • G01N21/85Investigating moving fluids or granular solids
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/18Water
    • G01N33/1826Water organic contamination in water
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/18Water
    • G01N33/1893Water using flow cells
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/01Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03Cuvette constructions
    • G01N21/05Flow-through cuvettes
    • G01N2021/052Tubular type; cavity type; multireflective
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/01Arrangements or apparatus for facilitating the optical investigation
    • G01N21/15Preventing contamination of the components of the optical system or obstruction of the light path
    • G01N2021/158Eliminating condensation
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/314Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • G01N2021/3181Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths using LEDs
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47Scattering, i.e. diffuse reflection
    • G01N21/49Scattering, i.e. diffuse reflection within a body or fluid
    • G01N21/51Scattering, i.e. diffuse reflection within a body or fluid inside a container, e.g. in an ampoule
    • G01N2021/513Cuvettes for scattering measurements
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/84Systems specially adapted for particular applications
    • G01N21/88Investigating the presence of flaws or contamination
    • G01N21/94Investigating contamination, e.g. dust
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00Features of devices classified in G01N21/00
    • G01N2201/06Illumination; Optics
    • G01N2201/062LED's
    • G01N2201/0627Use of several LED's for spectral resolution

Description

Method and device for an optical sensor for measuring the composition of a liquid

The present invention relates to a method and device for measuring the composition of a liquid and / or for determining bacteriological growth in a liquid, characterized by one or more light sources that successively emit light of different wavelength and are operatively connected to ie, light send through, at least a part of a transparent tube through which liquid to be examined flows, one or more light sensors which are also operatively connected to the transparent tube ie are exposed to at least a part of the light that falls through at least a part of the transparent tube , means for measuring the light absorption of the transparent tube and the liquid flowing through this tube, and software that translates the various light absorption signals into the concentration of organic or inorganic components or microorganisms present in the water or on the tube wall. The sensor according to the technology of the present invention is extremely suitable for measuring changes in liquids in horticulture, algae cultivation, waste water purification sector, food sector, drinking water sector, veterinary sector and medical sector.

preface

The technology according to the present invention is a practical implementation of a spectrophotometric determination of the concentration of impurities and / or reaction products and / or (micro) organisms in liquids in general and pipe networks in particular.

Description of the technology according to the present invention

In contrast to commercially available spectrophotometers, the sensor according to the technology of the present invention consists of a flow sensor instead of a sensor wherein the liquid is introduced into a cuvette and then placed in a spectrophotometer. Furthermore, the optical part of the sensor according to the technology of the present invention is built around a transparent tube that can be placed in an existing pipe system. As a result, the process liquid is measured inline without there being any direct contact between the light source and the light sensor on the one hand and the liquid on the other. Furthermore, the choice of material for the transparent tube is preferably such that, in addition to absorption of light by the liquid, any absorption of light due to the growth of organic or inorganic material is measured.

Figure 1 gives a schematic representation of the sensor according to the present invention. The sensor consists of a transparent tube 8 that is built into a pipe system by means of the coupling pieces 3. The tube is preferably flowed through with liquid that enters the transparent tube at location 4 and leaves the transparent tube at location 5 some time later. The wall of the transparent tube is schematically represented by 6. Light sources are arranged on or against or in the transparent tube, schematically represented by 1. On the other side of the tube, light-sensitive elements are provided, schematically represented by 2. Each light source can emit light of which at least a part falls on the light-sensitive part of at least one light-sensitive element. The transparent tube is preferably cast in a non-transparent casting resin, schematically represented by 7.

Now that the configuration is shown schematically, a further explanation of the invention follows first, followed by a number of preferred embodiments.

The connecting pieces 3 preferably consist of or are compatible with conventional pipe systems including PVC pipes for the drinking water and waste water industry, copper pipes and stainless steel pipes.

The light sources 1 preferably consist of a series of LEDs that all emit different wavelengths of light in the frequency range of preferably 400 nm to 1600 nm. The photosensitive elements 2 consisting of photodiodes and / or phototransistors and / or LDRs (photosensitive resistors) and / or photovoltaic cells (solar cells). The transparent tube 6 is preferably transparent PVC that is approved for use in food and drinking water. Other suitable polymers are polyacrylate, polyethylene, polycarbonate, PMMA or composites of these materials. Glass and quartz are also very suitable materials for the transparent tube 6. Even more preferably, the transparent tube complies with the RoHS directive. The housing in which the transparent tube is located can in principle be made of any type of material. The housing 7 preferably consists of a non-transparent casting resin for electronic components such as, for example, polyurethane resin that also complies with the RoHS directive. Use of a casting resin is emphatically part of the technology according to the present invention since it is essential to prevent condensation on the outside of the tube when the sensor is used in a practical environment. Condensation must be prevented because it disrupts the measurements. The LEDs and light-sensitive elements are operatively connected to a control unit which comprises at least one microcontroller which can successively switch the LEDs on and off and can measure the light absorption through the liquid and the wall of the transparent tube by means of an analog-to-digital converter (ADC). The control unit preferably also comprises a number of LEDs for alarming changes in the liquid or the wall of the tube. Furthermore, the microcontroller preferably contains software to translate the incoming signals into parameters that are relevant to the process and / or the quality of the fluid being investigated.

Now that the technology according to the present invention has been explained, a number of preferred embodiments follow: 1. As a light source, the sensor in Figure 1 can consist of an RGB (red-green-blue) LED. In fact, such an LED consists of 3 LEDs that are housed in a single housing (for example, a so-called 5mm LED). According to the definition in this application, an RGB LED consists of 3 light sources. In this way it is possible to measure the light absorption at 3 wavelengths using only a light-sensitive element 2. It is clear that also several RGB LEDs can be used next to each other, each with different properties. An incandescent lamp can also be considered as multiple light sources (since it produces light with different wavelengths) provided that they are provided with a correct fiiter set that can successively transmit light of different wavelengths or that the sensor is provided with different light-sensitive elements that each have a different light absorption characteristic as regards the absorption amplitude versus wavelength of the light. 2. A sensor in Figure 1 preferably consists of photosensitive elements with different properties (sensitivities) e.g. sensitivity to visible light and sensitivity to infrared radiation. Preferably, about 2 to 50 LEDs and 1 to 50 light-sensitive elements are mounted side by side in the sensor on the transparent tube. More preferably, about 2 to 10 LEDs and 1 to 10 photosensitive elements are mounted side by side in the sensor on the transparent tube. 3. The sensor preferably also measures light scattering at different wavelengths, after a light source 1 has been switched on, not only with the corresponding light-sensitive element 2 is measured (i.e. the element that lights directly into the light beam from light source 1) but also with neighboring light-sensitive elements to measure that do not receive or receive less light from light source 1 in the absence of light scattering. 4. The sensor is preferably mounted horizontally in a conduit so that any settling material either settles near the light sources and makes light penetration more difficult or settles near the light-sensitive elements and makes light penetration there more difficult. Sediment is also measured in this way. 5. Each LED is preferably protected against voltage peaks and / or current peaks caused by interference in the environment (electromagnetic compatibility is guaranteed) by protecting it with a diode or zener diode and / or a capacitor and / or a series resistor, all close to the LEDs are placed and preferably together form the optical part of the sensor that is injected into the polyurethane resin. This makes it possible to use long cables between the control unit and the optical part of the sensor without causing malfunctions or even damaging the LEDs. UTP cable is preferably used between the optical part of the sensor and the control unit.

Now that a few preferred embodiments have been explained, a number of applications follow: 1. The food industry to measure contamination of pipes, to do fingerprinting of, for example, alcoholic beverages, soft drinks, and to measure contamination / sedimentation in pipes. 2. The pulp & paper industry to measure the color (presence of humic acids and lignins) of process fluids by fingerprinting. The composition of process fluids is essential for the paper quality (whiteness of the paper). 3. Drinking water industry and waste water industry to measure contamination of pipes (sediment, fouling, scaling) and the concentration of humic acids in water. 4. Agricultural and veterinary sector, horticultural sector to measure the quality of drinking water and / or medicine residues or other additives in water and / or the quality of waste water. 5. Medical sector to measure the composition of urine. 6. Algae sensor by measuring specific absorption. 7. Bacteria sensor by measuring specific absorption

The sensor according to the technology of the present invention has the following unique properties: 1. A spectrophotometric amplitude versus frequency plot can be determined in a flow-through ratio! which is integrated into an existing pipeline network through which this liquid already flows. It appears that the sensor according to the present invention therefore behaves completely differently from commercially available sensors. The reason for this is that the sensor not only measures the composition of the fluid to be investigated inline and efficiently, but is also able to detect contamination of the pipeline network under exactly those process conditions that are relevant to practice. The contamination signal appears to provide a damping of the signal amplitude, which in many cases is the same for all wavelengths, so that with the sensor configuration according to the present invention a distinction can also be made between changes in the liquid composition and contamination of the pipe network. 2. The casting concept of the optical part of the sensor in polyurethane resin described in the present invention makes it possible to use the sensor under extreme conditions, i.e. under production conditions such as in water purification plants, the food industry or the paper industry. Due to the applied configuration, condensation of the light system is completely prevented so that, in contrast to commercially available systems, the sensor also works under humid conditions and with strong temperature changes. With commercially available spectrophotometers according to the state of the art, working in a production environment is not possible. 3. By mounting the part of the sensor that has flowed through water horizontally and level in the pipe network and ensuring that the light falls axially on the flow direction through the transparent tube (ie from top to bottom or from bottom to top), the sensor not only the composition of the liquid and contamination of the tube but also the settling of solid matter to the bottom of the tube. In many processes, this is a sign that process management must be adjusted, the flow conditions in the pipeline must be changed or the pipelines must be flushed to prevent future pollution. 4. The transparent tube is made of a material that is sensitive to undesirable properties of the liquid, such as sensitivity to contamination, for the purpose of detecting these contaminating properties of the liquid at an early stage. 5. The LEDs, each producing different wavelengths of light, can also be switched on simultaneously, thus measuring the effect of different wavelengths on light absorption. The detection of algae is mentioned as a non-limiting example where this provides extra information. 6. The LEDs in the optical sensor part are protected by (a) (zener) diode (s), and / or capacitors and / or series resistors to ensure proper functioning in an industrial environment (ensuring electromagnetic compatibility of the sensor). 7. Software in the control unit that contains at least one microcontroller and / or microprocessor and an analog to digital converter and a control for the light sources, can be adjusted to any type of process so that when the desired process conditions are exceeded, an alarm message is given by means of warning LEDs on the control unit or a software alarm (RS232, RS485, SMS etc.).

Due to the properties of the sensor listed in the above points, it appears to provide much more information about the properties of a liquid in pipe networks than can be expected on the basis of a spectrophotometer.

Example 1

A solution of Coca Cola in water was diluted to the limit that discoloration could be seen with the naked eye. The liquid was then placed in a sensor according to the technology of the present invention. The diameter of the transparent tube was 25 mm. The applied LED was an RGB LED and the light-sensitive element an LDR (light dependent resistor) with a resistance of 10 kOhm. The LDR was placed in series with a resistor of 5 kOhm and connected to a voltage of 5 Volts. The voltage measured over the resistance of 5 kOhm by means of the ADC (analog to digital converter) of a microcontroller was a measure of the light output. The red, green and blue LEDs were switched on successively and the light output was measured. After this, the solution was diluted a factor of 3 and the procedure repeated. The light output turned out to be proportional to the Coca Cola concentration in the drinking water.

Example 2

A solution of microalgae was diluted to the level that the algae could just not be seen with the eye. Then the light absorption was measured in the same way as in experiment 1 (RGB LED, so 3 wavelengths of light). There was no measurable link between the light absorption of the green LED and the concentration of algae. However, there appeared to be a linear relationship between the light absorption, the red LED and the blue LED and the concentration of algae. From this it is concluded that the measurement can detect algae specifically and at low concentrations in drinking water. It is noted that it is known in the literature that algae under stress situations can produce carotenoids, which is commercially interesting for the production of these carotenoids. It follows from the experiment that it must be possible to monitor this process with the technology according to the present invention.

Example 3

As example 1 but now with a solution of methylene blue. It now appears that the absorption of the blue LED is hardly related to the concentration of methylene blue, while the red and green LED produce a signal whose light absorption increases proportionally to the concentration of methylene blue.

Example 4

As Example 1 but now a solution of 0.19 grams of humic acid ex Aldrich, product code 100910029 was dissolved in 900 ml of water with a few drops of ammonium hydroxide added to speed up the dissolution. 5 solutions were tested: drinking water with resp. zero g / l humic acid, 1.5 mg / l, 2.9 mg / l, 5.9 mg / l, 35 mg / l and 211 mg / l. The absorption of red, green and blue light was measured for all samples by the technology of the present invention and the light absorption logarithm was plotted against the humic acid concentration logarithm for each of the colors. The result was a linear relationship in which it was found that it is possible to measure concentrations of humic acids in water to around 1 mg / l.

Claims (14)

  1. A sensor for measuring the properties of a liquid characterized by • a first transparent tube, provided on the outside with • at least 2 LEDs each producing light with a different wavelength of which at least a part shines through the first transparent tube • wherein said first transparent tube is also provided with at least a first light-sensitive element or series of light-sensitive elements that together can detect at least the absorption of light with 2 wavelengths; means for placing the transparent tube in an existing pipeline network and flowing through with the liquid to be examined ie, reducers • liquid to be examined in the pipe network that flows in and out of the first transparent tube • a control unit with at least one microprocessor or microcontroller which is operatively connected to at least one analog-to-digital converter which is operatively connected to at least the first light-sensitive element • means to turn the LEDs on or off via the microcontroller or microprocessor • casting resin that surrounds the optical components of the sensor part and closes it off from the environment to prevent condensation • software that interprets the signals measured by the sensor and converts them into information over the liquid or the pipework through which the liquid flows
  2. Sensor according to claim 1, wherein the first transparent tube is mounted horizontally and level in the pipe network so that the liquid flows horizontally through the sensor and wherein the light falls axially through the sensor (from top to bottom or from bottom to top), which is realized by mounting the LEDs and the light-sensitive elements axially on the flow direction of the water.
  3. Sensor according to one of the preceding claims 1 and 2, wherein the first transparent tube is made of transparent PVC or PMMA or polycarbonate or glass.
  4. Sensor according to one of the preceding claims 1 to 3, wherein at least one LED is protected against electrical and / or electromagnetic disturbances from the environment by means of a diode and / or zener diode and / or capacitor.
  5. Sensor according to one of the preceding claims 1 to 4, wherein the LEDs are switched on and off alternately and the light absorption is measured at a wavelength in each case.
  6. Sensor according to one of the preceding claims 1 to 5, wherein measurements are taken under conditions that more than 1 LED is switched on at the same time, so that the influence of light at a first wavelength on absorption at a second wavelength is measured.
  7. Sensor according to one of the preceding claims 1 to 6, wherein light scattering is measured by switching on at least a first LED and subsequently measuring the light absorption with a light-sensitive element that does not fall directly into the light beam of this first LED.
  8. 8. Algae sensor according to one of the preceding claims 1 to 7.
  9. Sensor for detecting humic acids in water according to one of the preceding claims 1 to 3.
  10. Sensor according to one of the preceding claims 1 to 7 for measuring the quality of process water in paper production processes.
  11. Sensor for measuring the drinking water quality of cattle according to one of the preceding claims 1 to 7.
  12. Sensor for measuring the quality of waste water according to one of the preceding claims 1 to 7.
  13. Sensor for measuring the presence of bacteria according to one of the preceding claims 1 to 7.
  14. A method for measuring the properties of a liquid flowing through a conduit characterized by a sensor according to any one of the preceding claims 1 to 13.
NL1040884A 2014-02-03 2014-07-14 Method and device for an optical sensor for measuring the composition of a liquid. NL1040884C2 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
NL1040648 2014-02-03
NL1040648 2014-02-03
NL1040884 2014-07-14
NL1040884A NL1040884C2 (en) 2014-02-03 2014-07-14 Method and device for an optical sensor for measuring the composition of a liquid.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL1040884A NL1040884C2 (en) 2014-02-03 2014-07-14 Method and device for an optical sensor for measuring the composition of a liquid.

Publications (1)

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NL1040884C2 true NL1040884C2 (en) 2015-08-06

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4181610A (en) * 1975-07-14 1980-01-01 Takeda Chemical Industries, Ltd. Blood leak detector suitable for use with artificial kidneys
GB2256043A (en) * 1991-03-19 1992-11-25 Welsh Water Enterprises Ltd Organic pollutant monitor
US20030058450A1 (en) * 2001-09-25 2003-03-27 Mosley R. Matthew Instrument and method for testing fluid characteristics
US20100157302A1 (en) * 2008-12-18 2010-06-24 Denso Corporation Liquid fuel property detection system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4181610A (en) * 1975-07-14 1980-01-01 Takeda Chemical Industries, Ltd. Blood leak detector suitable for use with artificial kidneys
GB2256043A (en) * 1991-03-19 1992-11-25 Welsh Water Enterprises Ltd Organic pollutant monitor
US20030058450A1 (en) * 2001-09-25 2003-03-27 Mosley R. Matthew Instrument and method for testing fluid characteristics
US20100157302A1 (en) * 2008-12-18 2010-06-24 Denso Corporation Liquid fuel property detection system

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