CA2236765A1 - Ozone sensor - Google Patents
Ozone sensor Download PDFInfo
- Publication number
- CA2236765A1 CA2236765A1 CA 2236765 CA2236765A CA2236765A1 CA 2236765 A1 CA2236765 A1 CA 2236765A1 CA 2236765 CA2236765 CA 2236765 CA 2236765 A CA2236765 A CA 2236765A CA 2236765 A1 CA2236765 A1 CA 2236765A1
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- CA
- Canada
- Prior art keywords
- corona discharge
- electrical signal
- light emission
- generate
- ozone sensor
- 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.)
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Abstract
An ozone sensor circuit comprising a corona discharge means which produces lightemissions, means to detect said light emission and generate an electrical signal in response to the intensity of said light emission.
Description
CA 0223676~ 1998-0~-0~
Field of Invention This invention relates to improvements in the sensing of ozone production in ozone generators using the corona discharge principle.
Ba~k3~ nll of Invention When ozone generators are used for medical purposes, it is n~cess~ry to measure and control the ozone concentration precisely. It is common that ozone generators heretofore known, based on the corona discharge principle, use UV photospectrometes to measure the ozone concentration Many ozone generator systems, however, due to economical considerations must be able ltO function without photospectrometers and therefore suffer from a number of disadvantages:
(a) In some ozone generator systems a sensor based on electrically sensing the high voltage current to the generator is used. It is, however, very difficult tofilter out the low frequency carrier wave and only sense the current due to the corona discharge.
(b) In previous ozone generator sensor designs the measured values are dependentof the electrical currerlt or electromagnetic field of the generator or high voltage transformer. In the case of a dielectric failure for example, there are electric l;UllClll~ and fields generated, which can be taken as corona measurements by an electrical sensor.
(c) In other ozone generator systems a sensor based on sensing the corona discharge is used. Unfortunately, it is very difficult to filter out the low frequency carrier wave and only sense the current due to the corona discharge.
CA 0223676~ 1998-0~-0~
(d) In all previous ozone generator sensor designs the measured values are independent of the type of feed gas used. To be able to sense the type of feed-gas used has been a long felt but unsolved need in the industry.
Objects and ~dv~nt~es Accordingly several objects and advantages of the present invention are:
(a) to provide an ozone sensor which responds only to the corona discharge and is not affected by electrical r~ulle~ and electrom~gn~tic fields.
(b) to provide an ozone sensor which responds in a linear fashion to the corona discharge and consequently the amount of ozone produced.
(c) to provide an ozone sensor which has a different response according to the type of feed gas used. The wavelength of the light produced in the corona discharge shifts if pure oxygen is not used.
It is an aspect of this invention l:o provide an ozone sensor circuit comprising a corona discharge means which produces light emission means and to detect said light emission and generate an e]ectrical signal in respon,se to the intensity of said light emission.
It is a further aspect of this invention to provide an ozone sensor circuit comprising a corona discharge means, means to tr;msmit light emitted from said silent corona discharge, means to detect said light emission an~ generate an electrical signal in response thereto.
It is yet another aspect of this invention to provide an ozone sensor circuit comprising a corona discharge means, means to tr;msmit light emitted from said silent corona discharge, means to detect said light emission and generate an electrical signal in response thereto, means to amplify said electrical signa], means to measure said electrical signal, means to com.pare said electrical signal to a preset value and generate a difference output signal, means to generate a high alternating voltage, said difference output signal applied to CA 0223676~ 1998-0~-0~
said means to generate a high voltage, said high alternating voltage connected to said corona discharge me~ms, said silent corona discharge held at an intensity level which transmits said light emission. to m~int~in said difference output signal at a zero or small value.
It is another aspect of this invention to provide an ozone sensor comprising corona discharger means having an inlet and outlet for gas to pass therethrough; sensor means to detect the intensity of the light emission from said corona discharge means as said gas passes through said corona discharge means and generate an electrical signal in response to said detected intensity of light.
List of D-dW;~
In drawings which illustrate embodiments of the invention:
Figure 1 is a cross-sectional elevation view of the line A-A of the Ozone Generator shown in Fig.2.
Figure 2 is an cross-sectional plan vielw of the Ozone Generator partially in schematic form showing the interconnections to the Photodiode, the Microcontroller and the High Voltage Power Supply, Reference Numerals In D,~wi~
generator end cap 11 photodiode leads 2 ozone gas outlet 1'! corona discharge space 3 feed gas inlet 13 ozone generator 4 optical light pipe 14 ozonation apparatus photodiode 6 high voltage electrode 7 dielectric member 8 high voltage lead 9 high voltage power supply microcontroller CA 0223676 7 1998 - 0, - 0, Summary of Invention A corona discharge is produced between the dielectric member and the outer high voltage electrode. The light emission from the corona discharge is guided through a light pipe to a photodiode n-lounted outside the generator housing. The output from the photodiode is amplified and~ measured by a microcontroller. The microcontroller m~int~in~ the ozone concentration at the preset level.
The photodiode is shielded and mounted exterior to the ozone generator and therefore is not affected by the electromagnetic fields from the generator high voltage circuits.
The wavelength of the light emission lrom the corona discharge is dependent on the type of feed-gas and Ihe oxygen contents of the feed-gas can therefore be monitored.
The generator is constructed in such a fashion that the light pipe and photodiode can easily be incorporated into the design.
Detailed Description of Preferred EmboJ;...~..l-Fi3~c 1 to 2 The ozonation apparatus illustrated comprises an ozone generator 13, an optical light pipe 4, a photodiode 5, a microcontroller l O and a high voltage power supply 9.
The ozone generator 13 is defined by means of high voltage electrodes 6, dielectric member 7 and generator end caps 1. For example, in one embodiment as shown in Figures 1 and 2, there is a firsl: inner electrode 6 which can comprise of a stainless steel tube. A dielectric member 7 such as a glass tube is adjac:ent the first inner electrode 6. Next there is an outer electrode 6 spaced outwardly from the dielectric member 7 and inner electrode 6 so as to define a corona discharge space 12. The corona discharge space 12 is defined between outer high voltage electrode 6 and dielectric member 7. The feed gas is supplied through feed-gas inlet hole 3, and the ozone produced in the generator is discharged through outlet hole 2.
The optical li~ht pipe 4 extends through the end cap 1 and is centered to the corona discharge space 12. The corona discharge space 12 in the embodiment shown in Figures 1 and 2 CA 0223676~ 1998-0~-0~
comprises an annular cylindrical space. In the plefelled embodiment as shown in Fig. 2 the optical light pipe is made of quartz glass with a diameter of 5 mm and polished on both ends.
However the optical light pipe can also be made from other glass materials with a light tr~n~mi.~ion down to 250 nm.
A photodiode 5 is mounted in close proximity to the end of the light pipe 4 and connected to the microcontroller 10 with two leads 11. The photodiode uses gallium phosphide in its sensing element, with a response in the range of 190 to 500 nm with a peak response at 400 nm. Other opl:ical sensors in combination with filters can be used to achieve a peak response in the 350 to 450 nm range.
The microcontroller controls the frequency and voltage output of the high voltage power supply 9. The high voltage power supply 9 will typically apply a voltage of approximately 5000 volts a.c., across the electrodes 6, so as to produce the corona discharge.
The high voltage power supply is coImected to the ozone generator 13 with the two high voltage leads 8.
From the description above, a number of advantages of the ozone generator are achieved:
(a) The ozone sensor respollds only to the corona discharge and is not affected by electrical ~;ull~llL~ and electrom~gn~ti~ fields.
(b) The ozone sensor responds in a linear fashion to the corona discharge and consequently the amoumt of ozone produced.
(c) The ozone sensor has a different response according to the type of feed gas used. The wavelength of the light produced in the corona discharge shifts if pure oxygen is not used. The sensor can therefore also be used to test if the feed gas is pure oxygen only, since the wavelength of the light emission from the corona discharge is dependent on the type of feed-gas.
CA 0223676~ 1998-0~-0~
Operation-F~ 1 to 2 An electrostatic field or corona discha.rge is created between the electrodes 6 and dielectric member 7 by conn~cting them to the high voltage power supply 9 with the high voltage leads 8. An exterior oxygen supply is then used to supply oxygen though the feed-gas inlet hole 3 which is then passed through the cylindrical space between the high voltage electrode 6 and the dielectric :member 7. A small percentage of the oxygen (i.e. 0-5%) is converted to ozone and pushed out the ozone gas outlet hole 2.
In the prefer:red embodiment, as shown in Fig. 2, the light emission from the corona discharge in the corona discharge space 12 is tr~n~mitted through the optical light pipe 4 to the photodiodl 5. The photodiode 5 is connected to the microcontroller 10 with two leads 11.
The signal from the photodiode 5 is in the pA (pico amp 10-l2) range and must therefore be amplified witl1 a pre-amplifier in the microcontroller assembly. The leads 11 must also be kept very short and the whole photodiode and microcontroller assemblies must be well shielded against electromagnetic fields.
The photodiode in the prefel-~d embodiment uses gallium phosphide in its sensing element, with a peak response at 400 nm. If the feed-gas as is changed from pure oxygen to air, for example, the photodiode response decreases several hundred percent for the same corona discharge due to the shift in the emitted spectra.
The ozone concentration is kept constant by using a closed feed-back loop with the microcontroller sensing the output from the photodiode and controlling the frequency and voltage of the output of the high voltage power supply 9, which controls the intensity of the corona discha:rge.
In another embodiment the photodiode is replaced by photosensor modules which can be purchased, for example, from ~m~m~.co Photonics K.K. Such light sensor modules include a photomultiplier tube (i.e. amplify the light read) and operating power supply. These light sensors modu:les accept direct light input or an optical fibre with an optical fibre adaptor.
These photosensors have good response characteristics in the 350 to 450 nm range.
CA 0223676~ 1998-0~-0~
In both cases of the photodiode and photosensor, these devices monitor and read the intensity of the corona discharge.
The above identified description contains many specificities (?), these should not be construed as limitations on the scope of the invention, but rather as an exemplification of one preferred embodiment thereof. Many other variations are possible. For example the light pipe can consist of a fiberoptic cable, and the generator high voltage electrodes and dielectric elements can be made iin dirrerell~ configurations. Accordingly, the scope of the invention should be determined not by the embodiment(s) illustrated, but by the appended claims and their legal equivalents.
Field of Invention This invention relates to improvements in the sensing of ozone production in ozone generators using the corona discharge principle.
Ba~k3~ nll of Invention When ozone generators are used for medical purposes, it is n~cess~ry to measure and control the ozone concentration precisely. It is common that ozone generators heretofore known, based on the corona discharge principle, use UV photospectrometes to measure the ozone concentration Many ozone generator systems, however, due to economical considerations must be able ltO function without photospectrometers and therefore suffer from a number of disadvantages:
(a) In some ozone generator systems a sensor based on electrically sensing the high voltage current to the generator is used. It is, however, very difficult tofilter out the low frequency carrier wave and only sense the current due to the corona discharge.
(b) In previous ozone generator sensor designs the measured values are dependentof the electrical currerlt or electromagnetic field of the generator or high voltage transformer. In the case of a dielectric failure for example, there are electric l;UllClll~ and fields generated, which can be taken as corona measurements by an electrical sensor.
(c) In other ozone generator systems a sensor based on sensing the corona discharge is used. Unfortunately, it is very difficult to filter out the low frequency carrier wave and only sense the current due to the corona discharge.
CA 0223676~ 1998-0~-0~
(d) In all previous ozone generator sensor designs the measured values are independent of the type of feed gas used. To be able to sense the type of feed-gas used has been a long felt but unsolved need in the industry.
Objects and ~dv~nt~es Accordingly several objects and advantages of the present invention are:
(a) to provide an ozone sensor which responds only to the corona discharge and is not affected by electrical r~ulle~ and electrom~gn~tic fields.
(b) to provide an ozone sensor which responds in a linear fashion to the corona discharge and consequently the amount of ozone produced.
(c) to provide an ozone sensor which has a different response according to the type of feed gas used. The wavelength of the light produced in the corona discharge shifts if pure oxygen is not used.
It is an aspect of this invention l:o provide an ozone sensor circuit comprising a corona discharge means which produces light emission means and to detect said light emission and generate an e]ectrical signal in respon,se to the intensity of said light emission.
It is a further aspect of this invention to provide an ozone sensor circuit comprising a corona discharge means, means to tr;msmit light emitted from said silent corona discharge, means to detect said light emission an~ generate an electrical signal in response thereto.
It is yet another aspect of this invention to provide an ozone sensor circuit comprising a corona discharge means, means to tr;msmit light emitted from said silent corona discharge, means to detect said light emission and generate an electrical signal in response thereto, means to amplify said electrical signa], means to measure said electrical signal, means to com.pare said electrical signal to a preset value and generate a difference output signal, means to generate a high alternating voltage, said difference output signal applied to CA 0223676~ 1998-0~-0~
said means to generate a high voltage, said high alternating voltage connected to said corona discharge me~ms, said silent corona discharge held at an intensity level which transmits said light emission. to m~int~in said difference output signal at a zero or small value.
It is another aspect of this invention to provide an ozone sensor comprising corona discharger means having an inlet and outlet for gas to pass therethrough; sensor means to detect the intensity of the light emission from said corona discharge means as said gas passes through said corona discharge means and generate an electrical signal in response to said detected intensity of light.
List of D-dW;~
In drawings which illustrate embodiments of the invention:
Figure 1 is a cross-sectional elevation view of the line A-A of the Ozone Generator shown in Fig.2.
Figure 2 is an cross-sectional plan vielw of the Ozone Generator partially in schematic form showing the interconnections to the Photodiode, the Microcontroller and the High Voltage Power Supply, Reference Numerals In D,~wi~
generator end cap 11 photodiode leads 2 ozone gas outlet 1'! corona discharge space 3 feed gas inlet 13 ozone generator 4 optical light pipe 14 ozonation apparatus photodiode 6 high voltage electrode 7 dielectric member 8 high voltage lead 9 high voltage power supply microcontroller CA 0223676 7 1998 - 0, - 0, Summary of Invention A corona discharge is produced between the dielectric member and the outer high voltage electrode. The light emission from the corona discharge is guided through a light pipe to a photodiode n-lounted outside the generator housing. The output from the photodiode is amplified and~ measured by a microcontroller. The microcontroller m~int~in~ the ozone concentration at the preset level.
The photodiode is shielded and mounted exterior to the ozone generator and therefore is not affected by the electromagnetic fields from the generator high voltage circuits.
The wavelength of the light emission lrom the corona discharge is dependent on the type of feed-gas and Ihe oxygen contents of the feed-gas can therefore be monitored.
The generator is constructed in such a fashion that the light pipe and photodiode can easily be incorporated into the design.
Detailed Description of Preferred EmboJ;...~..l-Fi3~c 1 to 2 The ozonation apparatus illustrated comprises an ozone generator 13, an optical light pipe 4, a photodiode 5, a microcontroller l O and a high voltage power supply 9.
The ozone generator 13 is defined by means of high voltage electrodes 6, dielectric member 7 and generator end caps 1. For example, in one embodiment as shown in Figures 1 and 2, there is a firsl: inner electrode 6 which can comprise of a stainless steel tube. A dielectric member 7 such as a glass tube is adjac:ent the first inner electrode 6. Next there is an outer electrode 6 spaced outwardly from the dielectric member 7 and inner electrode 6 so as to define a corona discharge space 12. The corona discharge space 12 is defined between outer high voltage electrode 6 and dielectric member 7. The feed gas is supplied through feed-gas inlet hole 3, and the ozone produced in the generator is discharged through outlet hole 2.
The optical li~ht pipe 4 extends through the end cap 1 and is centered to the corona discharge space 12. The corona discharge space 12 in the embodiment shown in Figures 1 and 2 CA 0223676~ 1998-0~-0~
comprises an annular cylindrical space. In the plefelled embodiment as shown in Fig. 2 the optical light pipe is made of quartz glass with a diameter of 5 mm and polished on both ends.
However the optical light pipe can also be made from other glass materials with a light tr~n~mi.~ion down to 250 nm.
A photodiode 5 is mounted in close proximity to the end of the light pipe 4 and connected to the microcontroller 10 with two leads 11. The photodiode uses gallium phosphide in its sensing element, with a response in the range of 190 to 500 nm with a peak response at 400 nm. Other opl:ical sensors in combination with filters can be used to achieve a peak response in the 350 to 450 nm range.
The microcontroller controls the frequency and voltage output of the high voltage power supply 9. The high voltage power supply 9 will typically apply a voltage of approximately 5000 volts a.c., across the electrodes 6, so as to produce the corona discharge.
The high voltage power supply is coImected to the ozone generator 13 with the two high voltage leads 8.
From the description above, a number of advantages of the ozone generator are achieved:
(a) The ozone sensor respollds only to the corona discharge and is not affected by electrical ~;ull~llL~ and electrom~gn~ti~ fields.
(b) The ozone sensor responds in a linear fashion to the corona discharge and consequently the amoumt of ozone produced.
(c) The ozone sensor has a different response according to the type of feed gas used. The wavelength of the light produced in the corona discharge shifts if pure oxygen is not used. The sensor can therefore also be used to test if the feed gas is pure oxygen only, since the wavelength of the light emission from the corona discharge is dependent on the type of feed-gas.
CA 0223676~ 1998-0~-0~
Operation-F~ 1 to 2 An electrostatic field or corona discha.rge is created between the electrodes 6 and dielectric member 7 by conn~cting them to the high voltage power supply 9 with the high voltage leads 8. An exterior oxygen supply is then used to supply oxygen though the feed-gas inlet hole 3 which is then passed through the cylindrical space between the high voltage electrode 6 and the dielectric :member 7. A small percentage of the oxygen (i.e. 0-5%) is converted to ozone and pushed out the ozone gas outlet hole 2.
In the prefer:red embodiment, as shown in Fig. 2, the light emission from the corona discharge in the corona discharge space 12 is tr~n~mitted through the optical light pipe 4 to the photodiodl 5. The photodiode 5 is connected to the microcontroller 10 with two leads 11.
The signal from the photodiode 5 is in the pA (pico amp 10-l2) range and must therefore be amplified witl1 a pre-amplifier in the microcontroller assembly. The leads 11 must also be kept very short and the whole photodiode and microcontroller assemblies must be well shielded against electromagnetic fields.
The photodiode in the prefel-~d embodiment uses gallium phosphide in its sensing element, with a peak response at 400 nm. If the feed-gas as is changed from pure oxygen to air, for example, the photodiode response decreases several hundred percent for the same corona discharge due to the shift in the emitted spectra.
The ozone concentration is kept constant by using a closed feed-back loop with the microcontroller sensing the output from the photodiode and controlling the frequency and voltage of the output of the high voltage power supply 9, which controls the intensity of the corona discha:rge.
In another embodiment the photodiode is replaced by photosensor modules which can be purchased, for example, from ~m~m~.co Photonics K.K. Such light sensor modules include a photomultiplier tube (i.e. amplify the light read) and operating power supply. These light sensors modu:les accept direct light input or an optical fibre with an optical fibre adaptor.
These photosensors have good response characteristics in the 350 to 450 nm range.
CA 0223676~ 1998-0~-0~
In both cases of the photodiode and photosensor, these devices monitor and read the intensity of the corona discharge.
The above identified description contains many specificities (?), these should not be construed as limitations on the scope of the invention, but rather as an exemplification of one preferred embodiment thereof. Many other variations are possible. For example the light pipe can consist of a fiberoptic cable, and the generator high voltage electrodes and dielectric elements can be made iin dirrerell~ configurations. Accordingly, the scope of the invention should be determined not by the embodiment(s) illustrated, but by the appended claims and their legal equivalents.
Claims (18)
1. An ozone sensor circuit comprising:
a. a corona discharge means which produces light emission, b. means to detect said light emission and generate an electrical signal in response to the intensity of said light emission.
a. a corona discharge means which produces light emission, b. means to detect said light emission and generate an electrical signal in response to the intensity of said light emission.
2. The ozone sensor circuit of claim 1 wherein said means to detect said light emission and generate an electrical signal produces a peak electrical signal output for a light transmission in the 350 to 450 nm range.
3. The ozone sensor circuit of claim 2 having a gas input and wherein said means to detect said light emission and generate an electrical signal produces an electrical signal output for a light transmission at 500 nm which is less than 80% of the electrical signal output for a light transmission at 400 nm whereby the oxygen content of said gas input can be determined due to the different light emission of different gases in the corona discharge.
4. The ozone sensor circuit of claim 1 wherein said means to detect said light emission and generate an electrical signal is enclosed inside an electromagnetic shield in order to shield said means from the electromagnetic fields generated by the said corona discharge means.
5. The ozone sensor circuit of claim 1 wherein said means to detect said light emission and generate an electrical signal responds in a substantially linear fashion to the said light emitted from the said corona discharge.
6. The ozone sensor circuit of claim 1 wherein the light emitted from said corona discharge communicates with an optical light pipe to the said means to detect said light emission and generate an electrical signal which is located outside the said corona discharge means.
7. The ozone sensor circuit of claim 1 wherein the electrical output signal from said means to detect said light emission and generate an electrical signal is amplified.
8. The ozone sensor circuit of claim 1 wherein the electrical output signal from said means to detect said light emission and generate an electrical signal is amplified and measured.
9. The ozone sensor circuit of claim 1 wherein the electrical output signal from said means to detect said light emission and generate an electrical signal is compared to a preset value and a difference output signal is generated,
10. The ozone sensor circuit of claim 9 wherein the said difference output signal is applied to high alternating voltage means which is supplying the power to said corona discharge means, thereby maintaining said silent corona discharge intensity at a preset level.
11. An ozone sensor circuit comprising:
a. a corona discharge means, b. means to transmit light emitted from said corona discharge, c. means to detect said light emission and generate an electrical signal in response thereto.
a. a corona discharge means, b. means to transmit light emitted from said corona discharge, c. means to detect said light emission and generate an electrical signal in response thereto.
12. An ozone sensor circuit comprising:
a. a corona discharge means, b. means to transmit light emitted from said corona discharge, c. means to detect said light emission and generate an electrical signal in response thereto, d. means to amplify said electrical signal, e. means to measure said electrical signal, f. means to compare said electrical signal to a preset value and generate a difference output signal, g. means to generate a high alternating voltage, h. said difference output signal applied to said means to generate a high voltage, i. said high alternating voltage connected to said corona discharge means, j. said corona discharge held at an intensity level which transmits said light emission to maintain said difference output signal at a zero or small value.
a. a corona discharge means, b. means to transmit light emitted from said corona discharge, c. means to detect said light emission and generate an electrical signal in response thereto, d. means to amplify said electrical signal, e. means to measure said electrical signal, f. means to compare said electrical signal to a preset value and generate a difference output signal, g. means to generate a high alternating voltage, h. said difference output signal applied to said means to generate a high voltage, i. said high alternating voltage connected to said corona discharge means, j. said corona discharge held at an intensity level which transmits said light emission to maintain said difference output signal at a zero or small value.
13. An ozone sensors comprising:
(a) corona discharge means having an inlet and outlet for gas to pass therethrough;
(b) sensors means to detect the intensity of the light emission from said coronadischarge means as said gas passes through said corona discharge means and generate an electrical signal in response to said detected intensity of light.
(a) corona discharge means having an inlet and outlet for gas to pass therethrough;
(b) sensors means to detect the intensity of the light emission from said coronadischarge means as said gas passes through said corona discharge means and generate an electrical signal in response to said detected intensity of light.
14. An ozone sensor as claimed in claim 13 wherein said gas is oxygen.
15. An ozone sensor as claimed in claim 14 wherein said corona discharge means produces ozone.
16. An ozone sensor as claimed in claim 15 wherein said intensity of light is proportional to the concentration of ozone.
17. An ozone sensor as claimed in claim 16 wherein the intensity is substantially linerally proportional to the concentration of ozone.
18. An ozone sensor as claimed in claim 17 wherein said electrical signal is substantially linerally proportional to the concentration of said ozone.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US4553497P | 1997-05-05 | 1997-05-05 | |
| US60/045,534 | 1997-05-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2236765A1 true CA2236765A1 (en) | 1998-11-05 |
Family
ID=21938461
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2236765 Abandoned CA2236765A1 (en) | 1997-05-05 | 1998-05-05 | Ozone sensor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2236765A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6280633B1 (en) | 1999-12-01 | 2001-08-28 | Fantom Technologies Inc. | Ozone sensor and method for use of same in water purification system |
-
1998
- 1998-05-05 CA CA 2236765 patent/CA2236765A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6280633B1 (en) | 1999-12-01 | 2001-08-28 | Fantom Technologies Inc. | Ozone sensor and method for use of same in water purification system |
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