Title of Invention | "A NOVEL MOISTURE SENSOR" |
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Abstract | A novel moisture sensor, which comprises 32-37 gauge, enameled copper coil wound on a porous tape cast tubular ceramic former enclosing a low density ceramic ferrite having diameter in the range of 10- 12mm, length in the range 100-120-cm. |
Full Text | The invention relates to a novel moisture sensor and a device for measuring moisture made thereof. This invention particularly relates to a sensor based on change in quality factor of a coil due to be absorption of moisture from high to low level. Measurement of moisture in general and gases in particular is very common in various types of applications especially for industrial processes where moisture sensitivity dictates product quality and yield. The various techniques for measuring moisture from extreme low to high value are mainly done in two methods. Which are the measurement of ac impedance and measurement of change in capacitance. In case of capacitative sensor a hygroscopic layer of aluminium oxide absorbs water molecules within its pores, depending on the water vapour pressure in its environment. The electrical capacitance is measured between the aluminium core of the sensor and the porous conductive gold layer on the outside. For conductive type sensor the hygroscopic material is either deposited on impervious insulating surfaces, on fibers or fabrics or on porous ceramics. These methods of detection suffer from various limitations such as, it will take a long time to come to equilibrium with the surrounding atmosphere, thus the dynamic response is poor and the indication of the system will show a lag, sometimes several hours. These methods of detection also suffer from various other limitations such as low sensitivity and high cost. To the best of our knowledge and belief there is no inductance type moisture sensor. The main object of the present invention is to provide a novel moisture sensor that obviates the above noted drawbacks. Another object of the present invention is to provide a novel moisture sensor that works on the principle of change in inductance. Yet another object of the present invention is to provide a moisture sensor having a tape cast porous ceramic of composition Still another object of the present invention is to provide a device incorporating the sensor of the present invention for measuring moisture having fine sensitivity in the range of 100 ppm to 400 ppm with 0.05% resolution and response time less than 3 seconds. The moisture sensor of the present invention essentially consists of a enameled copper coil wound on a porous tape-cast tubular ceramic former enclosing a low density ceramic ferrie. Accordingly the present invention provides a novel moisture sensor, which comprises 32-37 gauge, Enameled copper coil wound on a porous tape cast tubular ceramic former enclosing a low density ceramic ferrite having diameter in the range of 10-12mm, length in the range 100-120-cm. In an embodiment of the present invention the copper coil may have 30-40 turns. In another embodiment of the present invention the porous tape cast tubular former may be made using material of pore size in the range of 0.1-0.6μm and having a composition such as In yet another embodiment the ferrite core used may have permeability in the rnge of 2000-8000, inductance 10-50μH, Q factor 200-250. Accordingly, the present invention provides a device for measuring moisture, which comprises a novel moisture sensor, as, described above, being connected to an oscillator capable of inputting an angular frequency, the output of the said sensor being connected to a known Data Acquisition system. Field of application of the sensor of the present invention is for measuring moisture in any industrial process, some applications may be measurement moisture of powdered material, moisture present in non-toxic gases, agricultural field, food processing, for RH (relative humidity) measurement. The sensor works on the basic principle that a small voltage of certain frequency (800 KHz) is introduced to the sensor, the sensor shows some open circuit voltage, when it is placed in dry gas. When the moist gas is passed through the sample holder, due to the extremely small size of the pore, their Brownian motion will be limited, their energy will consequently be reduced and they will condense into liquid water. As a result the Q value will change. This change in Q value is measured as an index of moisture content at the testing zone. The novelty of the present invention resides in providing an inductance type moisture sensor. The inventive steps are providing an enameled copper coil wound on porous ceramic tubular tape cast former with ferrite core. The following examples illustrate the invention and the manner in which it may be carried out in practice, however, this should not be construed to limit the scope of the present invention. Example 1 An enameled copper wire of 32 gauge is wound on porous tubular ceramic with core of permeability 2300, its dc resistivity is > ohm, relative dissipation factor is is accommodation factor D 25°C is dry gas to 250 and its inductance is made to l0μH using 33 turns at 1MHz. Q & L value are measured by LCR meter (HP4284A). The resonance is adjusted to zero volts at dry gas. At l00ppm of gas moisture level the sensor output becomes 50m V. Example 2 An enameled copper wire of 32 gauge is wound on porous tubular ceramic with core of permeability 2300, its dc resistivity is > ohm, relative dissipation factor is is accommodation factor D 25°C is dry gas to 250 and its inductance is made to l0μH using 33 turns at 1MHz. The Q and L value are measured by LCR meter (HP4284A) and the resonance is adjusted to zero volts at dry gas. At 150ppm of gas moisture level the sensor output becomes l00mV. Example 3 An enameled copper wire of 32 gauge is wound on porous tubular ceramic with core of permeability 2300, its dc resistivity is > ohm, relative dissipation factor is is accommodation factor D 25°C is dry gas to 250 and its inductance is made to l0μH using 33 turns at 1MHz. LCR meter (HP4284A) measures the Q and L value and the resonance is adjusted to zero volts at dry gas. At 175ppm of gas moisture level the sensor output becomes 200m V. Example 4 An enameled copper wire of 32 gauge is wound on porous tubular ceramic with core of permeability 2300, its dc resistivity is > ohm, relative dissipation factor is is accommodation factor D 25°C is dry gas to 250 and its inductance is made to l0μH using 33 turns at 1MHz. The Q and L value are measured by LCR meter (HP4284A) and the resonance is adjusted to zero volts at dry gas. At 200ppm of gas moisture level the sensor output becomes 250mV. Example 5 An enameled copper wire of 32 gauge is wound on porous tubular ceramic with core of permeability 2300, its dc resistivity is > ohm, relative dissipation factor is is accommodation factor D 25°C is <. the q value is adjusted with> dry gas to 250 and its inductance is made to l0μH using 33 turns at 1MHz. The Q and L value are measured by LCR meter (HP4284A) and the resonance is adjusted to zero volts at dry gas. At 300ppm of gas moisture level the sensor output becomes 350mV. Example 6 An enameled copper wire of 32 gauge is wound on porous tubular ceramic with core of permeability 2300, its dc resistivity is > ohm, relative dissipation factor is ^ 1.6, temperature coefficient - 0.6 to + .6 106/K and D is accommodation factor D 25°C is dry gas to 250 and its inductance is made to l0μH using 33 turns at 1MHz. The Q and L value are measured by LCR meter (HP4284A) and the resonance is adjusted to zero volts at dry gas. At 400ppm of gas moisture level the sensor output becomes 1V. The main advantages of the device of this present invention are: 1. High resolution 2. High range (100 - 23.000ppm) 3. High stability 4. Low cost 5. Quick response ( We Claim: LA novel moisture sensor, which comprises 32-37 gauge, enameled copper coil wound on a porous tape cast tubular ceramic former enclosing a low density ceramic ferrite having diameter in the range of 10-12mm, length in the range 100-120-cm. 2. A novel moisture sensor as claimed in Claim 1 wherein the copper coil has 30-40 turns. 3. A novel moisture sensor as claimed in claim 1-2 wherein porous tape cast tubular former is made using material of pore size 0. l-0.6μm and having composition. Homogenizer (cyclohexanone) 0.90-1.10-wt% 4. A novel moisture sensor as claimed in Claim 1-3 wherein the said ceramic ferrite has permeability in the range of 2000-8000, inductance 10-50μH, Q (Magnification factor of the coil) factor 200-250. 5. A device for measuring moisture which comprises connecting the said novel moisture sensor as claimed in claim 1 to an oscillator for inputting an angular frequency, output of the said sensor being connected to a known data acquisition system. 6. A novel moisture sensor substantially as herein described with reference to the examples. |
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361-DEL-2001-Abstract (27-03-2001).pdf
361-DEL-2001-Claims (27-03-2001).pdf
361-DEL-2001-Correspondence-Others (27-03-2001).pdf
361-DEL-2001-Correspondence-PO (27-03-2001).pdf
361-DEL-2001-Description (Complete) (27-03-2001).pdf
361-DEL-2001-Form-1 (27-03-2001).pdf
361-DEL-2001-Form-2 (27-03-2001).pdf
361-DEL-2001-Form-3 (27-03-2001).pdf
Patent Number | 222433 | |||||||||||||||
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Indian Patent Application Number | 361/DEL/2001 | |||||||||||||||
PG Journal Number | 36/2008 | |||||||||||||||
Publication Date | 05-Sep-2008 | |||||||||||||||
Grant Date | 08-Aug-2008 | |||||||||||||||
Date of Filing | 27-Mar-2001 | |||||||||||||||
Name of Patentee | COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH | |||||||||||||||
Applicant Address | RAFI MARG, NEW DELHI-110 001, INDIA. | |||||||||||||||
Inventors:
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PCT International Classification Number | G01N 27/12 | |||||||||||||||
PCT International Application Number | N/A | |||||||||||||||
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