GB2223100A - Sensors and calibration device - Google Patents
Sensors and calibration device Download PDFInfo
- Publication number
- GB2223100A GB2223100A GB8822446A GB8822446A GB2223100A GB 2223100 A GB2223100 A GB 2223100A GB 8822446 A GB8822446 A GB 8822446A GB 8822446 A GB8822446 A GB 8822446A GB 2223100 A GB2223100 A GB 2223100A
- Authority
- GB
- United Kingdom
- Prior art keywords
- sensor
- calibration device
- crucible
- platinum
- alloy
- 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.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
- G01K7/18—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K15/00—Testing or calibrating of thermometers
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Abstract
A high temperature platinum resistance thermometer comprises an elongate quartz tube 2 within which is positioned the platinum winding 1. A positive potential offset voltage e.g. of 6 to 10 volts is applied to the platinum winding 1. Terminals 3 and 5 of the winding 1 can be connected to a bridge circuit so that the measured resistance of the platinum winding 1 is indicative of the temperature thereof. A calibration device comprises a cylindrical quartz tube 10 having a graphite crucible 12 positioned therein. A positive offset voltage is applied to the crucible 12 or to the partly molten metal therein. The calibration device can be used to calibrate the thermometer when inserted into the recess in the direction of arrow A. Application of the positive offset voltage has the effect of stopping or at least alleviating the migration of metallic vapours through the quartz sheath and so reducing combination of the metal part of the sensor or of the metal within the crucible of the calibration device. <IMAGE>
Description
SENSORS AND CALIBRATION DEVICES
This invention relates to sensors and calibration devices, and in particular but not exclusively to
High-Temperature Standard Platinum Resistance
Thermometers and High Purity Freezing Point Cells.
A known type of temperature sensor comprises a platinum winding housed within a quartz sheath. A problem with this type of sensor is that at elevated temperatures, the quartz tube is porous to some metallic vapours such as iron and copper. The migration of copper or other metallic vapours through the quartz sheath can lead to contamination of the platinum winding. The temperature reading derived from the sensor is affected according to the type of contaminant and degree of contamination. The type and degree of contamination differs according to differing positions on the earth surface.
It is an aim of the present invention to overcome this problem so as to provide a sensor which is not prone to such contamination over the range within which it is to be used.
According to the present invention, there is provided a sensor comprising a pure metal or an alloy of predetermined composition positioned within a quartz sheathe wherein a positive potential offset is applied to the pure metal or alloy for preventing migration of contaminating metallic vapours through the quartz sheath.
The sensor may include means or terminals for coupling the pure metal or alloy to a resistance measuring means for determining the temperature of the sensor in dependence upon its resistance.
The resistance measuring circuit is preferably a bridge circuit.
The pure metal or alloy is preferably in the form of a platinum winding.
According to the present invention, there is further provided a calibration device comprising a quartz sheath and a crucible for containing a pure metal or alloy in molten or solid state, wherein a positive potential offset is applied to the crucible or the pure metal or alloy for preventing migration of contaminating metallic vapours through the quartz sheath.
The positive potential is preferably in the region of 6 to 10 volts.
The crucible is preferably of graphite.
Maintaining the potential of the pure metal or pure alloy at a positive voltage above ground has the effect of stopping or at least alleviating the migration of metallic vapours through the quartz sheath and so reducing contamination of the pure metal component of the sensor.
Similarly, maintaining the potential of the crucible of the calibration device has the effect of stopping or at least alleviating the migration of metallic vapours through the quartz sheath thereby reducing contamination of the metal within the crucible, which metal is used in the calibration process of the temperature sensor.
The invention will now be described by way of example with reference to the accompanying drawing in which;
Figure 1 shows a high temperature platium resistance thermometer embodying the present invention: and
Figure 2 shows a freezing point cell embodying the present invention.
A platinum winding 1 is positioned at the closed end of an elongate quartz tube 2. The length of the quartz tube is sufficiently long as to provide an effective enclosure for the platinum winding 1. One end of the platinum winding is connected to a terminal 3 via a switch 4. The other end of the platinum winding 1 is coupled to a terminal 5.
When in use, the terminals 3 and 5 are connected to a bridge circuit (not shown) so that the measured resistance of the platinum winding 1 is indicative of the temperature thereof.
The end of the platinum winding 1 connected to the terminal 5 is connected to the positive terminal of a 9 volt battery 6. The negative terminal of the battery 6 is connected to earth. This battery 6 maintains the potential of the platinum winding 1 at 9 volts above ground. This serves to prevent the migration of contaminating metallic vapours, such as copper, through the quartz sheath particularly at elevated temperatures.
The embodiment described above is effective to a temperature well above 9620C.
Although the aforementioned embodiment has been described with reference to a High-Temperature Standard
Platinum Resistance Thermometer, embodiments of the invention may equally be applied to High Purity Freezing
Point Cells which involve the use of pure metals inside a quartz sheath. These pure metals may be zinc, silver.
gold, platiumm for example.
Figure 2 illustrates a sectional view of a calibration device embodying the present invention.
This calibration device is a freezing point cell and comprises a generally cylindrical quartz tube 10 having a graphite crucible 12 therein. The graphite crucible is designed for accomdating pure metals, for example, gold, silver, aluminium or zinc in either the molten or solid state.
The crucible 12 is connected to the ground potential via a battery 6. The positive terminal of the battery 6 is connected to the crucible 12 so as to maintain the potential of the crucible at a positive level above ground. This serves to prevent the migration of contaminating metallic vapours through the quartz tube 12. Alternatively, the positive terminal may be connected to the metal within the crucible 12.
The freezing point cell of Figure 2 can be used to calibrate the sensor illustrated in Figure 1. For example, pure silver may be placed within the crucible 12 and the entire cell may be placed within a furnace, when the silver is present in both liquid and solid state within the crucible 12, the precise temperature of the freezing point cell is known provided the silver is completely pure. Any contamination will change the freezing point of the silver.
At the freezing point of the silver, the platinum resistance thermometer of Figure 1 is inserted in the direction of arrow A into the concentric recess of the freezing point cell. The platinum and resistance thermometer can therefore be calibrated according to the known freezing point of silver.
Claims (10)
1. A sensor comprising a pure metal or an alloy of predetermined composition positioned within a quartz sheath wherein a positive potential offset is applied to the pure metal or alloy for preventing migration of contaminating metallic vapours through the quartz sheath.
2. A sensor according to claim 1 comprising means or terminals for coupling the pure metal or alloy to a resistance measuring means for determining the temperature of the sensor in dependence upon its resistance.
3. A sensor according to claim 2, wherein the resistance measuring circuit is a bridge circuit.
4. A sensor according to claim 1, claim 2 or claim 3, wherein the sensor comprises a pure metal of platinum.
5. A sensor according to claim 4, wherein the platinum is formed into a winding.
6. A calibration device comprising a quartz sheath and a crucible for containing a pure metal or alloy in molten or solid state, wherein a positive potential offset is applied to the crucible or the pure metal or alloy for preventing migration of contaminating metallic vapours through the quartz sheath.
7. A sensor or calibration device according to any one of claims 1 to 5 or claim 6, wherein the positive potential is in the region of 6 to 10 volts.
8. A calibration device according to claim 6 or claim 7 when dependent upon claim 6, wherein the crucible is of graphite.
9. A sensor substantially as herein before described with reference to Figure 1 of the accompanying drawings.
10. A calibration device substantially as herein before described with reference to Figure 2 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8822446A GB2223100A (en) | 1988-09-23 | 1988-09-23 | Sensors and calibration device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8822446A GB2223100A (en) | 1988-09-23 | 1988-09-23 | Sensors and calibration device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8822446D0 GB8822446D0 (en) | 1988-10-26 |
| GB2223100A true GB2223100A (en) | 1990-03-28 |
Family
ID=10644162
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8822446A Withdrawn GB2223100A (en) | 1988-09-23 | 1988-09-23 | Sensors and calibration device |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2223100A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10015481C1 (en) * | 2000-03-29 | 2001-09-27 | Heraeus Electro Nite Int | Sensor with a temperature-dependent measuring element |
| GB2376526A (en) * | 2001-06-13 | 2002-12-18 | Secretary Trade Ind Brit | Device for calibrating thermometers |
| US7063457B2 (en) * | 2003-09-04 | 2006-06-20 | Korea Research Institute Of Standards And Science | Fixed point cell for connection with the thermometer protecting tube and apparatus for estimating the lifetime of thermometer using the same |
| CN101281150B (en) * | 2008-04-30 | 2010-06-02 | 太仓宏大纺织仪器有限公司 | Melting point apparatus and method for eliminating melting point apparatus measuring value drift |
| DE102012201501A1 (en) | 2012-02-02 | 2013-08-08 | Ignatios Giannelis | Device for determining the temperature of a melt |
-
1988
- 1988-09-23 GB GB8822446A patent/GB2223100A/en not_active Withdrawn
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10015481C1 (en) * | 2000-03-29 | 2001-09-27 | Heraeus Electro Nite Int | Sensor with a temperature-dependent measuring element |
| US6462640B2 (en) | 2000-03-29 | 2002-10-08 | Heraeus Electro-Nite International N.V. | Sensor with a temperature-dependent measuring element |
| GB2376526A (en) * | 2001-06-13 | 2002-12-18 | Secretary Trade Ind Brit | Device for calibrating thermometers |
| GB2376526B (en) * | 2001-06-13 | 2004-06-02 | Secretary Trade Ind Brit | System for calibrating thermometers |
| US6939035B2 (en) | 2001-06-13 | 2005-09-06 | The Secretary Of State Of Her Majesty's Britannic Government | System for calibrating thermometers |
| US7063457B2 (en) * | 2003-09-04 | 2006-06-20 | Korea Research Institute Of Standards And Science | Fixed point cell for connection with the thermometer protecting tube and apparatus for estimating the lifetime of thermometer using the same |
| CN101281150B (en) * | 2008-04-30 | 2010-06-02 | 太仓宏大纺织仪器有限公司 | Melting point apparatus and method for eliminating melting point apparatus measuring value drift |
| DE102012201501A1 (en) | 2012-02-02 | 2013-08-08 | Ignatios Giannelis | Device for determining the temperature of a melt |
| WO2013113507A2 (en) | 2012-02-02 | 2013-08-08 | Giannelis Ignatios | Apparatus for determining the temperature of a melt |
| DE102012201501A9 (en) | 2012-02-02 | 2013-10-10 | Ignatios Giannelis | Device for determining the temperature of a melt |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8822446D0 (en) | 1988-10-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |