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WO1992019954A1 - Procede et montage destines au calibrage du point-zero - Google Patents

Procede et montage destines au calibrage du point-zero Download PDF

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Publication number
WO1992019954A1
WO1992019954A1 PCT/SE1992/000257 SE9200257W WO9219954A1 WO 1992019954 A1 WO1992019954 A1 WO 1992019954A1 SE 9200257 W SE9200257 W SE 9200257W WO 9219954 A1 WO9219954 A1 WO 9219954A1
Authority
WO
WIPO (PCT)
Prior art keywords
gap
zero
optical
channel
measuring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/SE1992/000257
Other languages
English (en)
Inventor
Gerdt Heinrich Fladda
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of WO1992019954A1 publication Critical patent/WO1992019954A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/27—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using photo-electric detection ; circuits for computing concentration
    • G01N21/274—Calibration, base line adjustment, drift correction
    • G01N21/276—Calibration, base line adjustment, drift correction with alternation of sample and standard in optical path
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/15—Preventing contamination of the components of the optical system or obstruction of the light path
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/85—Investigating moving fluids or granular solids
    • G01N21/8507—Probe photometers, i.e. with optical measuring part dipped into fluid sample

Definitions

  • This invention relates to a method for making zero-point calibration of the kind set forth in the preamble in claim 1, and an arrangement for providing the method.
  • Measurement of light absorption is a common method in order to determine the concentration of suspended material, particles and/or absorbing material in a flowing medium.
  • Zero-point measurements on clear water are often made at predetermined instances in order to have a reference constant value when measurements are made on suspended or absorbing material in a liquid.
  • durtying effects on the optical elements adjacent to a measuring gap can have deleterious influence on the measuring results even though zero- point measurements are made.
  • measurement of the concentration of fine material e.g. clay
  • the peak method is influenced by light intensity variations in the measuring gap in the signal processing method described in our copending PCT-application No PCT/SE90/00212, called the peak method.
  • the peak method is preferably executed by a measuring probe also described in the copending PCT-application No PCT/SE90/00212 having a quite narrow and shallow measuring gap having optical fibres to transport the light to and from the measuring gap.
  • a particular cleaning device including a brush is described, which reduces the risk for deleterious effects by dirt.
  • this kind of cleaning device has proven not to give all the cleaning effect needed, particularly when high concentrations of chemicals are used and micro- scratce ⁇ in the optical surfaces become choked-up.
  • the main object of the invention is to provide a method and an arrangement to provide zero-point calibration of a measuring probe while at the same time providing extra cleaning of the optical surfaces adjacent to the measuring gap of a measuring probe.
  • the compensation method according to the invention is based upon that at least one beam of gas or liquid passes the measuring gap and drives away all the medium bearing the suspension by having the beam or beams directed towards the surfaces of the optical elements adjacent to the measuring gap in order to give a cleaning effect of these surfaces.
  • FIG l shows a section through a schematic view of an embodiment of the arrangement according to the invention
  • FIG 2 shows a cross section of an embodiment of a measuring probe having the arrangement according to the invention
  • FIG 3 shows a diagram having graphs showing the result of measurement made with and without the arrangement according to the invention.
  • the schematically illustrated part of a measuring probe includes a measuring body 1 having a measuring gap 2 to which two optical fibres 3 and 4 are conducted, one from each side such that they end in two opposite side walls of the gap 2.
  • the measuring body 1 is provided with an inner cylindrical chamber 5 ending in a concentric cylindrical chamber 6 having essentially smaller diameter than the chamber 5 in the vicinity of the measuring gap 2.
  • the axis of the chambers 5 and 6 is in line with a symmetrical line through the measuring gap 2 parallel to its side walls.
  • a piston plunge 7 having a periphery adapted to the diameter of the inner chamber 5 is provided in the chamber 5.
  • a tube 8 having a channel 9 for clean gas, e.g. air, or liquid, e.g. water, is provided centrally in the piston plunge 7.
  • the outer diameter of the tube is adapted to the diameter of the chamber 6 and is conveyed through it.
  • the end 10 of the tube 8 turned towards the measuring gap is not hollow.
  • a through channel 11 perpendicular to the axis of the tube is provided near the end of the tube and having open connection with the channel 9.
  • the piston with its tube is shown in its protruding state, i.e. its position for reference measurement, having the through channel 11 placed directly in the measuring gap 2 between the surfaces of the optical fibres 3, 4 in the side walls of the measuring gap 2.
  • compressed air is fed through the channel 9 and is streaming out from both sides of the channel 11 towards the fibre surfaces forcing the medium having the suspension, particles or absorbing material away.
  • the compressed air could be streming for some time adequate to clean the fibre surfaces. This time could either be predetermined or determined by some adequate parameter, such as the time to the next preceding reference measurement or the actual concentration of suspended material or the like.
  • a reference measurement is made in the same manner than an ordinary measurement but through the channel 11. The exact measurement properties are not a part of this actual invention and are therefore not described.
  • the piston is controlled to retract plunge 7 with the tube 8 into the inside of the measuring body 1 such that the measuring gap 2 is free, and ordinary measurements on medium having a suspension, particles or absorbing material can be made.
  • a probe of the kind described in the PCT-application No PCT/SE90/00212 mentioned above is provided with an arrangement according to the invention.
  • a measuring body 15 is provided in two peaces having their interface in the section shown in FIG 2 and being screwed together by screws in screw holes 16.
  • a cavity 17 is provided in the body 15.
  • a measurement gap 18 is provided in an oblique surface of the probe.
  • a plate 22 having the narrow measuring gap 18 is screwed to the outer surface of an oblique part 19 of the body 15.
  • Optical fibres 23, 24 of the measuring device enter the cavity 17 in the probe body by a sealed extension pipe 25 and are arranged in curved loops to end at the measuring gap 18.
  • the probe is hermetically sealed. It is immersed in a flowing medium having the suspension and is mounted to the end of the extension pipe 25.
  • An arrangement to provide cleaning of the measuring gap 18 including the arrangement according to the invention is provided in the cavity 17.
  • a tube 28 having a cylidrical through hole is placed in an opening in the oblique part 19.
  • the hole in the tube 28 is widened in its end turned to the cavity in order to house a sealing 29.
  • a holding tub 30 having a through hole 31 is placed sealingly (sealing 32) around the inner part of the tub 28 and having its inner diameter adapted to the outer diameter of the tub 28.
  • the tub 30 has a flange 33 for holding nozzles 34 and 35.
  • a plug 36 is screwed through a wall of the body 15 opposite to the oblique surface having the measuring gap 18 and has a part sealingly fastened in the through hole of the tube 30.
  • the common axis of the tubes 28 and 30 and the plug 36 is in line with the symmetry axis of the measuring gap 18.
  • a hollow piston rod 40 with a piston plunge 38 is inserted in the hole 31 of the tube 30.
  • a chamber is provided on each side of the piston plunge 38, and the piston plunge is contollable to be moved to protrude or restric the piston rod 40 at will.
  • the piston is powered with air from a protrusion nozzle 34 discharging in a chamber 42 on the side of the piston 38 turned from the mouth when it is to be protruded.
  • the plug has a through hole 43 open to the through hole 31.
  • An adjustment plug 44 is screwed into the hole 64 from the outside, and the volume of the chamber 42 is thus adjustable.
  • the piston is powered with air from a restriction nozzle 35 discharging in a chamber on the side of the piston 38 turned towards the gap 18 when it is to be restricted.
  • the hollow piston rod 40 is carried to move through an opening in the sealing 29.
  • the hollow piston rod has a part 41 having smaller diameter than the part of the rod in the chamber 31 also moving in the cylindrical chamber 45 in the tube 28, the chamber 45 having its diameter adapted to the diameter of the part 40 of the piston rod in the chamber 31.
  • a neck 46 is provided between the rod parts 40 and 41.
  • the end of the chamber 45 turned towards the measuring gap 18 ends in an opening 47 having its diameter adapted to the diameter of the rod part 41, a neck 48 being provided as a stop for the neck 46, when the piston rod is controlled to protrude out through the measuring gap.
  • a through channel 49 perpendicular to the rod axis is provided at a distance from the neck 46 on the piston rod adapted to the distance from the neck 48 to the actual measuring gap 18.
  • the through channel 49 ends the hollow part of the piston rod providing a channel for pressurized reference medium.
  • the part 50 of the rod outside the channel 49 is not hollow.
  • a brush 51 is seated in the outer end of the part 49.
  • the piston 38, 40 is shown in its restricted position in FIG 2.
  • pressurized gas such as air, or clear liquid. This pushes the piston plunge 38 towards the tube 28 until the neck 41 abuts the neck 48.
  • pressurized medium from the nozzle 34 will be streaming out from the channel 49.
  • the pressurized medium through the nozzle 34 is shut off, and pressurized medium is fed into the chamber 31 through the nozzle 35 having its inlet extending into the hole 31 adjacent to the tube 57. This will push the piston plunge 38 towards the plug 36 until it abuts the inlet of the nozzle 34 extending into the chamber 42, i.e. to the position shown in FIG 2.
  • FIG 3 shows graphs of measuring results provided with and without the method according to the invention.
  • the intensity conditions for the lightbea are altered in the measuring gap during measurements on a suspension, e.g. by deposits on the optical surfaces. Therefore, the reference value will change, and new evaluations made on the earlier reference will be incorrect.
  • an automatic zero-point calibration will be made at intervals, which could be predetermined, e.g. programmed into a control and computing device from a key pad (not shown) , or based on particular measurement parameters, such as mean value changes or the like.
  • the zero-point calibrations are made while the air jet from the channel 49 keeps the measuring gap 18 void of all fluid including suspension. Consequently, the reference value will be that of clean air.
  • the ratio between the transmission coefficients of air and water is constant. The measured value for clean air therefore can be used to calculate a new reference value for clear water.

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  • Physics & Mathematics (AREA)
  • Biochemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Spectroscopy & Molecular Physics (AREA)

Abstract

L'invention se rapporte à un procédé et un à montage destinés à la mesure en continu du zéro de référence de l'espace de mesure optique (2; 18) d'une sonde de mesure. Ledit espace de mesure possède des optiques dont les surfaces sont placées en regard avec ledit espace de mesure. Ces optiques sont destinées à la transmission optique ou à la mesure de diffusion sur un milieu à écoulement incluant des matériaux de suspension des particules et/ou des matières absorbant la lumière. L'espace est totalement rempli par un milieu de référence, tel qu'un liquide ou un gaz, durant la mesure du zéro de référence. On obtient un effet de nettoyage des surfaces optiques en laissant circuler le milieu de référence sur lesdites surfaces optiques.
PCT/SE1992/000257 1991-04-25 1992-04-23 Procede et montage destines au calibrage du point-zero Ceased WO1992019954A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9101259A SE9101259D0 (sv) 1991-04-25 1991-04-25 Metod foer att kompensera foer ljusintensitetsfoeraendringar i ett optiskt maetgap vid bestaemning av halten suspenderat material
SE9101259-1 1991-04-25

Publications (1)

Publication Number Publication Date
WO1992019954A1 true WO1992019954A1 (fr) 1992-11-12

Family

ID=20382567

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1992/000257 Ceased WO1992019954A1 (fr) 1991-04-25 1992-04-23 Procede et montage destines au calibrage du point-zero

Country Status (2)

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SE (1) SE9101259D0 (fr)
WO (1) WO1992019954A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000026652A1 (fr) * 1998-10-30 2000-05-11 Optiguide Ltd. Hygrometres a point de rosee et capteurs d'humidite
EP1003028A1 (fr) * 1998-11-20 2000-05-24 Ching Fu Kuan Dispositif de mesure de l'opacité des liquides
US6926439B2 (en) 1998-10-30 2005-08-09 Optiguide Ltd. Dew point hygrometers and dew sensors
WO2008060235A1 (fr) * 2006-11-16 2008-05-22 Delaval Holding Ab Dispositif et procédé d'échantillonnage de lait
AT512728A3 (de) * 2013-07-19 2014-12-15 Ditest Fahrzeugdiagnose Gmbh Verfahren zur Kalibrierung eines Streulichtmessgerätes

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3892485A (en) * 1974-05-06 1975-07-01 Gen Electric Monitoring apparatus for measuring particles suspended in liquid and for measuring the opacity of the liquid
US4201477A (en) * 1978-01-16 1980-05-06 Fmc Corporation Suspended solids meter
US4299495A (en) * 1979-05-17 1981-11-10 Tokyo Shibaura Denki Kabushiki Kaisha Density meter
US4583859A (en) * 1984-03-30 1986-04-22 The Babcock & Wilcox Company Filter cleaning system for opacity monitor
WO1991000993A1 (fr) * 1989-07-10 1991-01-24 Fladda Gerdt H Appareil et procede de mesure
WO1991013340A1 (fr) * 1990-02-26 1991-09-05 Lys & Optik Procede de mesure d'une boue liquide

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3892485A (en) * 1974-05-06 1975-07-01 Gen Electric Monitoring apparatus for measuring particles suspended in liquid and for measuring the opacity of the liquid
US4201477A (en) * 1978-01-16 1980-05-06 Fmc Corporation Suspended solids meter
US4299495A (en) * 1979-05-17 1981-11-10 Tokyo Shibaura Denki Kabushiki Kaisha Density meter
US4583859A (en) * 1984-03-30 1986-04-22 The Babcock & Wilcox Company Filter cleaning system for opacity monitor
WO1991000993A1 (fr) * 1989-07-10 1991-01-24 Fladda Gerdt H Appareil et procede de mesure
WO1991013340A1 (fr) * 1990-02-26 1991-09-05 Lys & Optik Procede de mesure d'une boue liquide

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000026652A1 (fr) * 1998-10-30 2000-05-11 Optiguide Ltd. Hygrometres a point de rosee et capteurs d'humidite
US6575621B1 (en) 1998-10-30 2003-06-10 Optiguide Ltd. Dew point hygrometers and dew sensors
US6926439B2 (en) 1998-10-30 2005-08-09 Optiguide Ltd. Dew point hygrometers and dew sensors
EP1003028A1 (fr) * 1998-11-20 2000-05-24 Ching Fu Kuan Dispositif de mesure de l'opacité des liquides
WO2008060235A1 (fr) * 2006-11-16 2008-05-22 Delaval Holding Ab Dispositif et procédé d'échantillonnage de lait
AT512728A3 (de) * 2013-07-19 2014-12-15 Ditest Fahrzeugdiagnose Gmbh Verfahren zur Kalibrierung eines Streulichtmessgerätes
AT512728B1 (de) * 2013-07-19 2015-03-15 Ditest Fahrzeugdiagnose Gmbh Verfahren zur Kalibrierung eines Streulichtmessgerätes

Also Published As

Publication number Publication date
SE9101259D0 (sv) 1991-04-25

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