CA2266567A1 - Measurement of specific dissolved gases - Google Patents
Measurement of specific dissolved gases Download PDFInfo
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- CA2266567A1 CA2266567A1 CA 2266567 CA2266567A CA2266567A1 CA 2266567 A1 CA2266567 A1 CA 2266567A1 CA 2266567 CA2266567 CA 2266567 CA 2266567 A CA2266567 A CA 2266567A CA 2266567 A1 CA2266567 A1 CA 2266567A1
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Abstract
A method and apparatus for the measurement of a specific dissolved gas in a liquid. The apparatus comprises a gas-permeable membrane for separation of dissolved gas from the liquid; a gas collecting chamber communicating with and disposed on the side of said membrane remote from the liquid for collecting dissolved gas separated from the liquid; a second chamber for receiving a gas absorbing or adsorbing material for the specific dissolved gas; means for interconnecting the second chamber to one gas collecting chamber to allow contact of the dissolved gas with the gas absorbing or adsorbing material; and pressure measuring means for providing a measurement of the difference of pressure of the gas resulting from the absorption or adsorption of the specific selected gas, thereby providing a measure of the quantity of the selected specific gas present in the liquid. The method involves interfacing the liquid to be measured with a gas-permeable membrane to allow permeation and separation of dissolved gas from the liquid, and confining separated gas to a chamber; establishing equilibrated pressure of the separated gas within the chamber representative of the sum of partial pressures of all dissolved gases; contacting the gas with a material that absorbs or adsorbs the specific selected gas to be measured, and determining the pressure reduction resulting from the absorption or adsorption of the specific selected gas, to provide a measure of the specific selected gas present in the liquid.
Description
TITLE OF THE INVENTION
Measwement Of S~cific Dissolved Gases.
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to the measurement of specific dissolved gases.
Measwement Of S~cific Dissolved Gases.
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to the measurement of specific dissolved gases.
2. Description of the Prior Art The measurement of gases, such as Oz, NZ, COz, that are dissolved in water is important for assessing changes relevant to a wide range of natural and anthropogenic processes. However, few sensors for dissolved gases are available commercially, and those that are available are generally unacceptable in terms of precision and accwacy, particularly for long-term deployment. Current methods for measuring dissolved gases, typically require collection of water samples and laboratory analysis.
Techniques for measuring total dissolved gas and fluid vapor pressure (gas tension) in liquids are known. A known device known as a Gas Tension Device (GTD) measures total dissolved gas pressure and using a gas permeable membrane.
A limitation of the known techniques, is the inability or difficulty in measuring 2 0 specific gases, such as O2, Nz, and/or CO2.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and apparatus for the measurement of specific dissolved gases.
2 5 A specific abject of the present invention is to provide a method and apparatus for the measurement of dissolved O2, N2, and/or COZ partial pressures.
It has been found that the concentration of a specific dissolved gas in a liquid can be determined by the separation of the dissolved gases from the liquid and the selective removal, for example by absorption or adsorption, of that specific gas, in conjunction with the measurement pressure difference resulting from the selective removal of the specific gas of interest.
The present invention provides a method for the measurement of a specific selected dissolved gas in a liquid, comprising: interfacing the liquid to be measured with a gas-permeable membrane to allow permeation and separation of dissolved gas from the liquid, and confining separated gas to a chamber; establishing equilibrated pressure of the separated gas within the chamber representative of the sum of partial pressures of all dissolved gases; contacting the gas with a material that absorbs or adsorbs the specific selected gas to be measured, and determining the pressure reduction resulting from the absorption or adsorption of the specific selected gas, to provide a measure of the specific selected gas present in the liquid.
The present invention also provides an apparatus for the measurement of a specific dissolved gas in a liquid, comprising: a gas-permeable membrane for separation of dissolved gas from the liquid; a gas collecting chamber communicating with and disposed on the side of said membrane remote from the liquid for collecting dissolved gas separated from the liquid; a second chamber for receiving a gas absorbing or 2 0 adsorbing material for the specific dissolved gas; means for interconnecting the second chamber to one gas collecting chamber to allow contact of the dissolved gas with the gas absorbing or adsorbing material; and pressure measuring means for providing a measurement of the difference of pressure of the gas resulting from the absorption or adsorption of the specific selected gas, thereby providing a measure of the quantity of the 2 5 selected specific gas present in the liquid.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic representation of one embodiment of the invention.
Fig. 2 is a schematic representation of an embodiment of the invention, specifically illustrating the volumes referred to in the Example and Fig. 3.
Fig. 3 is a schematic representation of the duty cycle of a dissolved oxygen sensor.
Fig. 4 is a schematic representation of another embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to Fig. I, the present invention includes an outer enclosure 1 having an opening 2. Closing the opening 2 is a gas-permeable membrane 3 that interfaces with the surrounding liquid 4, for which the dissolved gas is to be measured.
The gas-permeable membrane 3 is backed by a rigid ~rmeable spacer/suppolt member 5.
The spacer/support member 5 provides a distributed volume within which the gases behind the membrane 3 can equilibrate with the dissolved gases in the liquid 4, and also acts as a rigid support against hydrostatic pressure acting on the membrane 3.
The permeable support member S is preferably supported with a rigid second support member 6. A passageway 7 through the support member 6, interconnects the 2 0 volume disposed within the permeable spacer/support member 5, with a first valve 1 I, a first chamber 10, a second valve 12, and to the interior of a second chamber 8 which contains a gas absorbing or adsorbing material 9. A pressure sensor 14 shown associated with chamber 10 measures the pressure at various stages of operation as will be described.
2 5 It should be noted that the first chamber 10 may be integrated with the pressure sensor 14, or be a separate component, depending on the choice of pressure sensor.
Techniques for measuring total dissolved gas and fluid vapor pressure (gas tension) in liquids are known. A known device known as a Gas Tension Device (GTD) measures total dissolved gas pressure and using a gas permeable membrane.
A limitation of the known techniques, is the inability or difficulty in measuring 2 0 specific gases, such as O2, Nz, and/or CO2.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and apparatus for the measurement of specific dissolved gases.
2 5 A specific abject of the present invention is to provide a method and apparatus for the measurement of dissolved O2, N2, and/or COZ partial pressures.
It has been found that the concentration of a specific dissolved gas in a liquid can be determined by the separation of the dissolved gases from the liquid and the selective removal, for example by absorption or adsorption, of that specific gas, in conjunction with the measurement pressure difference resulting from the selective removal of the specific gas of interest.
The present invention provides a method for the measurement of a specific selected dissolved gas in a liquid, comprising: interfacing the liquid to be measured with a gas-permeable membrane to allow permeation and separation of dissolved gas from the liquid, and confining separated gas to a chamber; establishing equilibrated pressure of the separated gas within the chamber representative of the sum of partial pressures of all dissolved gases; contacting the gas with a material that absorbs or adsorbs the specific selected gas to be measured, and determining the pressure reduction resulting from the absorption or adsorption of the specific selected gas, to provide a measure of the specific selected gas present in the liquid.
The present invention also provides an apparatus for the measurement of a specific dissolved gas in a liquid, comprising: a gas-permeable membrane for separation of dissolved gas from the liquid; a gas collecting chamber communicating with and disposed on the side of said membrane remote from the liquid for collecting dissolved gas separated from the liquid; a second chamber for receiving a gas absorbing or 2 0 adsorbing material for the specific dissolved gas; means for interconnecting the second chamber to one gas collecting chamber to allow contact of the dissolved gas with the gas absorbing or adsorbing material; and pressure measuring means for providing a measurement of the difference of pressure of the gas resulting from the absorption or adsorption of the specific selected gas, thereby providing a measure of the quantity of the 2 5 selected specific gas present in the liquid.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic representation of one embodiment of the invention.
Fig. 2 is a schematic representation of an embodiment of the invention, specifically illustrating the volumes referred to in the Example and Fig. 3.
Fig. 3 is a schematic representation of the duty cycle of a dissolved oxygen sensor.
Fig. 4 is a schematic representation of another embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to Fig. I, the present invention includes an outer enclosure 1 having an opening 2. Closing the opening 2 is a gas-permeable membrane 3 that interfaces with the surrounding liquid 4, for which the dissolved gas is to be measured.
The gas-permeable membrane 3 is backed by a rigid ~rmeable spacer/suppolt member 5.
The spacer/support member 5 provides a distributed volume within which the gases behind the membrane 3 can equilibrate with the dissolved gases in the liquid 4, and also acts as a rigid support against hydrostatic pressure acting on the membrane 3.
The permeable support member S is preferably supported with a rigid second support member 6. A passageway 7 through the support member 6, interconnects the 2 0 volume disposed within the permeable spacer/support member 5, with a first valve 1 I, a first chamber 10, a second valve 12, and to the interior of a second chamber 8 which contains a gas absorbing or adsorbing material 9. A pressure sensor 14 shown associated with chamber 10 measures the pressure at various stages of operation as will be described.
2 5 It should be noted that the first chamber 10 may be integrated with the pressure sensor 14, or be a separate component, depending on the choice of pressure sensor.
The selected gas absorbing or adsorbing material 9 must absorb or adsorb only the gas being sensed. Preferably, the material will be a solid, non-volatile, and will not react significantly with water vapour. It should remain a solid and not become liquid or change its volume appreciably with time.
For dissolved oxygen sensing, a mixture found suitable contained super-activated carbon, sodium sulphite, pyrogallol, and sodium hydroxide crystals. For COZ an absorbent found suitable was Ca(OH)2 and NaOH in the form of a commercial product known as Ascarite.
There are no known absorbents/adsorbents with the desired attributes for NZ
and therefore the partial pressure thereof cannot be measured directly. However, a measure of the partial pressure of NZ can be determined indirectly by the measurement/removal of OZ and making and estimate from the remaining gases. The errors incurred by the assumptions involved in the estimate are small due to the fact that the partial pressure of N2 is very large compared to trace gases, such as COZ and Ar. Further, the natural change in the partial pressures of trace gases occurring in oceans, lakes, river or streams are typically very small.
A suitable micro controller 15 controls the timing of the valve operations and can be used to record the pressure and temperature measurements.
In operation, the chamber 8 is supplied with a material 9 that absorbs or adsorbs 2 0 the specific gas, or gasses, to be measured. Initially valves 11 and 12 will be closed.
When the device is disposed within the liquid to be analysed, valve I 1 is opened. With valve 11 open, and valve 12 closed, dissolved gases from the liquid 4 permeates the permeable membrane 3 and permeable support member S and accumulates in chamber L0. After equilibrium is established, the pressure sensor 14 provides a measure of the gas 2 5 tension, or the sum of the partial pressures of all dissolved gases, including water vapour.
After this first pressure measurement is taken, valve 11 is closed and valve 12 is opened.
For dissolved oxygen sensing, a mixture found suitable contained super-activated carbon, sodium sulphite, pyrogallol, and sodium hydroxide crystals. For COZ an absorbent found suitable was Ca(OH)2 and NaOH in the form of a commercial product known as Ascarite.
There are no known absorbents/adsorbents with the desired attributes for NZ
and therefore the partial pressure thereof cannot be measured directly. However, a measure of the partial pressure of NZ can be determined indirectly by the measurement/removal of OZ and making and estimate from the remaining gases. The errors incurred by the assumptions involved in the estimate are small due to the fact that the partial pressure of N2 is very large compared to trace gases, such as COZ and Ar. Further, the natural change in the partial pressures of trace gases occurring in oceans, lakes, river or streams are typically very small.
A suitable micro controller 15 controls the timing of the valve operations and can be used to record the pressure and temperature measurements.
In operation, the chamber 8 is supplied with a material 9 that absorbs or adsorbs 2 0 the specific gas, or gasses, to be measured. Initially valves 11 and 12 will be closed.
When the device is disposed within the liquid to be analysed, valve I 1 is opened. With valve 11 open, and valve 12 closed, dissolved gases from the liquid 4 permeates the permeable membrane 3 and permeable support member S and accumulates in chamber L0. After equilibrium is established, the pressure sensor 14 provides a measure of the gas 2 5 tension, or the sum of the partial pressures of all dissolved gases, including water vapour.
After this first pressure measurement is taken, valve 11 is closed and valve 12 is opened.
Opening of the valve 12, allows contact of the gas with the absorber or adsorber 9, which removes the selected gas, or gases, thus lowering the pressure. A
second pressure measurement by the pressure sensor 14 then provides a measure of the amount of gas absorbed or adsorbed, and hence a measure of that specific gas that was dissolved in the liquid.
It can be seen that having the volume of chamber 10 and the free volume (excluding the volume of the absorber/adsorber 9) of chamber 8 equal will simplify calculations. If volumes differ, pressure values can be adjusted in accordance with the Ideal Gas Law, as indicated in the example below.
Example Following is an example of the operation of the instrument as a dissolved oxygen sensor, with reference to Fig. 2 and Fig. 3.
Step 1: At time t = 0 (see Fig. 3), valve 1 (valve 11 in Fig. 2) is open and valve 2 (valve 12 in Fig. 2) is closed. The instalment is left in this state until the dissolved gases in sensing volume Va (see Fig. 2) are in equilibrium with the dissolved gases in the water This time is shown as t = t,. The time period (t = 0 to t=t,) is the equilibration time of the instrument which varies with the choice of membrane thickness and the volume Va, typically tens of minutes. The pressure sensor sensing volume Va now records the gas 2 0 tension of the water. The pressure of the sensing volume Vb (see Fig. 2) is the partial pressure of primarily nitrogen from the previous measurement, which is denoted by P"'2.
From the Ideal Gas Law we can write:
Va~ l Va(P~N2+ P~02) ...... I
V,,P'h VtrP~'2 ...... (2) 2 5 relating the pressure of the current measurement P' to the temperature T
assuming the number of moles of gas is constant and the temperature T is constant. The internal temperature T of the instrument is measured and stored to memory.
Step 2: At time t = t,, valve 1 is closed then valve 2 is opened. The gases redistribute within the volume defined by Vb. The chemical absorbent now removes the oxygen from the enclosed system. Once all the oxygen has been removed from the enclosed system (at time t = tz) we have:
(Oxygen removal) (Va + Vb) P'z = Vb P''z + Va(P'NZ +I''~oz) ...... (3) P'b = P'a P'z ...... (4) From (3) we get:
P'N2 ~ (Va + Vb))P'2 - V,,P' 12~ !W a ....
Substituting (5) into ( 1 ) we ,g~etV:
P~oz = I''~ - P' z [l + VblVa +P'-'z(~Ib/Va I ~ ...... (6) we see that if P'z = P'-'z then P'oz = P', - P'z as would be expected. The excess nitrogen in the system from the previous measurement is 'diluted' by a factor of V,./'Va .
In another simpler embodiment of the invention, with reference to Fig. 1, the valve 1 I is eliminated. This embodiment requires that the absorption/adsorption rate of material 9, for the specific selected gas be significantly faster than the permeation/diffusivity rate of the membrane. The operation involves a first pressure measurements with valve 12 closed and a second pressure measurement with the valve 12 open thereby subjecting the gas to the absorber/adsorber, whereby the reduction in pressure provides a measure of the specific gas removed.
2 0 Fig. 4 illustrates another embodiment of the invention. Referring to Fig.
4, this embodiment, as in the embodiment of Fig. 1, includes a gas-permeable membrane 23 for interfacing with the surrounding liquid 24, a rigid permeable spacer/support member 25, and a rigid support member 26. A passageway 27 through the support member 26 interconnects with a chamber 28 containing a gas absorbing or adsorbing material 29 selected to absorb or adsorb the specific selected gas to be measured. A
pressure sensor 34 compares the pressure difference between the chamber 29 and an evacuated chamber 38 of a conventional gas tension device (GTD) 30 which provides a measure of the total pressure of all dissolved gases. The pressure difference between units 30 and 20 provides a measure of the specific gas removed.
second pressure measurement by the pressure sensor 14 then provides a measure of the amount of gas absorbed or adsorbed, and hence a measure of that specific gas that was dissolved in the liquid.
It can be seen that having the volume of chamber 10 and the free volume (excluding the volume of the absorber/adsorber 9) of chamber 8 equal will simplify calculations. If volumes differ, pressure values can be adjusted in accordance with the Ideal Gas Law, as indicated in the example below.
Example Following is an example of the operation of the instrument as a dissolved oxygen sensor, with reference to Fig. 2 and Fig. 3.
Step 1: At time t = 0 (see Fig. 3), valve 1 (valve 11 in Fig. 2) is open and valve 2 (valve 12 in Fig. 2) is closed. The instalment is left in this state until the dissolved gases in sensing volume Va (see Fig. 2) are in equilibrium with the dissolved gases in the water This time is shown as t = t,. The time period (t = 0 to t=t,) is the equilibration time of the instrument which varies with the choice of membrane thickness and the volume Va, typically tens of minutes. The pressure sensor sensing volume Va now records the gas 2 0 tension of the water. The pressure of the sensing volume Vb (see Fig. 2) is the partial pressure of primarily nitrogen from the previous measurement, which is denoted by P"'2.
From the Ideal Gas Law we can write:
Va~ l Va(P~N2+ P~02) ...... I
V,,P'h VtrP~'2 ...... (2) 2 5 relating the pressure of the current measurement P' to the temperature T
assuming the number of moles of gas is constant and the temperature T is constant. The internal temperature T of the instrument is measured and stored to memory.
Step 2: At time t = t,, valve 1 is closed then valve 2 is opened. The gases redistribute within the volume defined by Vb. The chemical absorbent now removes the oxygen from the enclosed system. Once all the oxygen has been removed from the enclosed system (at time t = tz) we have:
(Oxygen removal) (Va + Vb) P'z = Vb P''z + Va(P'NZ +I''~oz) ...... (3) P'b = P'a P'z ...... (4) From (3) we get:
P'N2 ~ (Va + Vb))P'2 - V,,P' 12~ !W a ....
Substituting (5) into ( 1 ) we ,g~etV:
P~oz = I''~ - P' z [l + VblVa +P'-'z(~Ib/Va I ~ ...... (6) we see that if P'z = P'-'z then P'oz = P', - P'z as would be expected. The excess nitrogen in the system from the previous measurement is 'diluted' by a factor of V,./'Va .
In another simpler embodiment of the invention, with reference to Fig. 1, the valve 1 I is eliminated. This embodiment requires that the absorption/adsorption rate of material 9, for the specific selected gas be significantly faster than the permeation/diffusivity rate of the membrane. The operation involves a first pressure measurements with valve 12 closed and a second pressure measurement with the valve 12 open thereby subjecting the gas to the absorber/adsorber, whereby the reduction in pressure provides a measure of the specific gas removed.
2 0 Fig. 4 illustrates another embodiment of the invention. Referring to Fig.
4, this embodiment, as in the embodiment of Fig. 1, includes a gas-permeable membrane 23 for interfacing with the surrounding liquid 24, a rigid permeable spacer/support member 25, and a rigid support member 26. A passageway 27 through the support member 26 interconnects with a chamber 28 containing a gas absorbing or adsorbing material 29 selected to absorb or adsorb the specific selected gas to be measured. A
pressure sensor 34 compares the pressure difference between the chamber 29 and an evacuated chamber 38 of a conventional gas tension device (GTD) 30 which provides a measure of the total pressure of all dissolved gases. The pressure difference between units 30 and 20 provides a measure of the specific gas removed.
In operation, as in the embodiment of Fig. 1, dissolved gases in the liquid 24 diffuse through the membrane 23, passing through the permeable support member 25 to the absorbent chamber 28. The membrane diffusivity (related to membrane thickness) is chosen so that it takes longer for the gases to equilibrate with the dead volume of the absorbent chamber than it does for the specific gas to be absorbed. Thus the pressure produced is the pressure of all dissolved gases minus the partial pressure of the gas removed.
The difference in pressure, as measured by pressure sensor 34, between a conventional gas tension device 30, and the unit 20, which includes the gas absorbing chamber 28, provides a measure of the specific gas removed.
It will be understood that the present invention can take various forms and that it ca.n be utilized to measure gases other than detailed in the example, by using an appropriate absorber or adsorber, as discussed above.
The difference in pressure, as measured by pressure sensor 34, between a conventional gas tension device 30, and the unit 20, which includes the gas absorbing chamber 28, provides a measure of the specific gas removed.
It will be understood that the present invention can take various forms and that it ca.n be utilized to measure gases other than detailed in the example, by using an appropriate absorber or adsorber, as discussed above.
Claims (8)
1. A method for the measurement of a specific selected dissolved gas in a liquid, comprising:
interfacing the liquid to be measured with a gas-permeable membrane to allow permeation and separation of dissolved gas from the liquid, and confining separated gas to a chamber;
establishing equilibrated pressure of the separated gas within the chamber representative of the sum of partial pressures of all dissolved gases;
contacting the gas with a material that absorbs or adsorbs the specific selected gas to be measured; and determining the pressure reduction resulting from the absorption or adsorption of the specific selected gas, to provide a measure of the specific selected gas present in the liquid.
interfacing the liquid to be measured with a gas-permeable membrane to allow permeation and separation of dissolved gas from the liquid, and confining separated gas to a chamber;
establishing equilibrated pressure of the separated gas within the chamber representative of the sum of partial pressures of all dissolved gases;
contacting the gas with a material that absorbs or adsorbs the specific selected gas to be measured; and determining the pressure reduction resulting from the absorption or adsorption of the specific selected gas, to provide a measure of the specific selected gas present in the liquid.
2. The method of Claim 1, further comprising:
providing a first gas pressure measurement of the gas within the chamber, prior to contacting the gas with a material that absorbs or adsorbs the specific selected gas to be measured;
providing a second gas pressure measurement after contacting the gas and absorbing or adsorbing the specific selected gas; and determining the difference between the first and second gas pressure measurement, whereby the reduction of the pressure provides a measure of the gas removed and hence a measure of the specific selected gas that is present in the liquid.
providing a first gas pressure measurement of the gas within the chamber, prior to contacting the gas with a material that absorbs or adsorbs the specific selected gas to be measured;
providing a second gas pressure measurement after contacting the gas and absorbing or adsorbing the specific selected gas; and determining the difference between the first and second gas pressure measurement, whereby the reduction of the pressure provides a measure of the gas removed and hence a measure of the specific selected gas that is present in the liquid.
3. The method of Claim 1, wherein the selected gas is dissolved O2 or CO2.
4. An apparatus for the measurement of a specific dissolved gas in a liquid, comprising:
a gas-permeable membrane for separation of dissolved gas from the liquid;
a gas collecting chamber communicating with and disposed on the side of said membrane remote from the liquid for collecting dissolved gas separated from the liquid;
a second chamber for receiving a gas absorbing or adsorbing material for the specific dissolved gas;
means for interconnecting the second chamber to one gas collecting chamber to allow contact of the dissolved gas with the gas absorbing or adsorbing material; and pressure measuring means for providing a measurement of the difference of pressure of the gas resulting from the absorption or adsorption of the specific selected gas, thereby providing a measure of the amount of the selected specific gas present in the liquid.
a gas-permeable membrane for separation of dissolved gas from the liquid;
a gas collecting chamber communicating with and disposed on the side of said membrane remote from the liquid for collecting dissolved gas separated from the liquid;
a second chamber for receiving a gas absorbing or adsorbing material for the specific dissolved gas;
means for interconnecting the second chamber to one gas collecting chamber to allow contact of the dissolved gas with the gas absorbing or adsorbing material; and pressure measuring means for providing a measurement of the difference of pressure of the gas resulting from the absorption or adsorption of the specific selected gas, thereby providing a measure of the amount of the selected specific gas present in the liquid.
5. The apparatus of Claim 4, further comprising:
first valve means for allowing selective communication between the gas-permeable membrane and the first chamber; and second valve means interconnecting the second chamber with the first chamber for selectively allowing contact of the gas with the gas absorbing or adsorbing material.
first valve means for allowing selective communication between the gas-permeable membrane and the first chamber; and second valve means interconnecting the second chamber with the first chamber for selectively allowing contact of the gas with the gas absorbing or adsorbing material.
6. The apparatus of Claim 5, further comprising a controller for activating the first and second valves.
7. The apparatus of Claim 5, further comprising timer means and means responsive to the timer means to activate the first and second valves.
8. The apparatus of Claim 4, further including a permeable support member supporting the permeable membrane.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US20840298A | 1998-12-10 | 1998-12-10 | |
| US09/208,402 | 1998-12-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2266567A1 true CA2266567A1 (en) | 2000-06-10 |
Family
ID=29711507
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2266567 Abandoned CA2266567A1 (en) | 1998-12-10 | 1999-03-22 | Measurement of specific dissolved gases |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2266567A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109632568A (en) * | 2018-12-31 | 2019-04-16 | 北京科泰特科技发展有限公司 | A kind of air detecting device |
| US11471823B2 (en) | 2019-02-12 | 2022-10-18 | Haffmans B.V. | System and method for separating a gas mixture |
-
1999
- 1999-03-22 CA CA 2266567 patent/CA2266567A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109632568A (en) * | 2018-12-31 | 2019-04-16 | 北京科泰特科技发展有限公司 | A kind of air detecting device |
| US11471823B2 (en) | 2019-02-12 | 2022-10-18 | Haffmans B.V. | System and method for separating a gas mixture |
| US11964231B2 (en) | 2019-02-12 | 2024-04-23 | Haffmans B.V. | System and method for separating a gas mixture |
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| Date | Code | Title | Description |
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| FZDE | Dead |