DEVICE FOR SETTING AND CONTROLLING THE HUMIDITY OF A GAS

Abstract

A device for setting and controlling the humidity of a gas including elements which are adapted to realize a flow of a gas in the device during operation thereof; elements which are adapted to perform a humidity setting action on gas flowing through the device during operation thereof, including at least two members for the gas to flow through, arranged in parallel, namely at least one of a drying member and a humidifying member, and at least one inactive member; and means for controlling access to the tubular members of the humidity setting elements, at least at one end of the tubular members, in dependence of an actual value as measured during operation of the device and a reference value of the humidity of the gas.

Claims

1. A device for setting and controlling the humidity of a gas, comprising: flow generating means which are adapted to realize a flow of a gas in the device during operation thereof; humidity setting means which are adapted to perform a humidity setting action on gas flowing through the device during operation thereof, comprising at least two tubular members for the gas to flow through, arranged in parallel; humidity sensing means for sensing the humidity of the gas in the device; and controlling means for controlling access to the tubular members of the humidity setting means, at least at one end of the tubular members, in dependence of the humidity of the gas as sensed by the humidity sensing means during operation of the device and a reference value of the humidity; wherein at least one of the tubular members of the humidity setting means is an active tubular member comprising one of 1) a humidity decreasing tubular member adapted to let gas flow through and decrease the humidity of the gas, and 2) a humidity increasing tubular member adapted to let gas flow through and increase the humidity of the gas, and wherein at least one of the tubular members of the humidity setting means is an inactive tubular member adapted to just let gas flow through without performing a humidity setting action on the gas.

2. The device according to claim 1, wherein the humidity setting means comprise at least two active tubular members and at least one inactive tubular member, and wherein each of the active tubular members is associated with at least one inactive tubular member, in a parallel arrangement, and wherein both the humidity decreasing tubular member and humidity increasing tubular member are associated with the inactive tubular member.

3. (canceled)

4. The device according to claim 1, wherein the controlling means comprise valve means which are adapted to set an extent to which each of the tubular members of the humidity setting means is open at an end of the tubular members facing the humidity sensing means, or wherein the valve means are furthermore adapted to set an extent to which at least the active tubular member of the humidity setting means is open at the other end of the tubular member, or wherein the valve means are adapted to set the extent to which at least the active tubular member of the humidity setting means is open in a corresponding manner for both ends of the tubular member.

5. (canceled)

6. (canceled)

7. The device according to claim 4, wherein the controlling means comprise drive means for setting the position of the valve means, and wherein the controlling means are adapted to control operation of the drive means in dependence of the humidity of the gas as sensed by the humidity sensing means during operation of the device and the reference value of the humidity.

8. The device according to claim 4, wherein the valve means comprise a slidably arranged plate, at an end of at least two tubular members of the humidity setting means, which is provided with an opening for allowing gas to flow through the plate, or wherein the plate is associated with all of the tubular members of the humidity setting means, and wherein the controlling means are adapted to determine the position of the plate with respect to the tubular members of the humidity setting means in dependence of the humidity of the gas as sensed by the humidity sensing means during operation of the device and the reference value of the humidity.

9. (canceled)

10. (canceled)

11. The device according to claim 4, wherein the valve means comprise a first plate and a second plate coupled to the first plate, wherein both plates are slidably arranged, one at a first end of at least two tubular members of the humidity setting means, and the other at a second end of the tubular members, wherein both plates are provided with an opening for allowing gas to flow through the respective plate, and wherein the positions of the openings of the plates with respect to the tubular members as seen in a flow-through direction of the tubular members correspond to each other.

12. The device according to claim 4, wherein the valve means comprise a rotatably arranged disc, which is associated with an end of at least two tubular members of the humidity setting means, and which is provided with openings for allowing gas to flow through the disc.

13. The device according to claim 1, further comprising a user interface coupled to the controlling means for allowing a user of the device to set the reference value of the humidity, and wherein the humidity sensing means comprise a sensor which is arranged at a position close to the tubular members of the humidity setting means.

14. (canceled)

15. The device according to claim 1, further comprising a measuring chamber for accommodating at least the humidity sensing means, the measuring chamber having two openings in a wall thereof, which openings are adapted to allow for exchange of gas between an interior and an exterior of the measuring chamber, and a tubular connection member extending outside of the measuring chamber for interconnecting the openings of the measuring chamber, wherein the flow generating means are adapted to realize circulation of the gas through both the connection member and the measuring chamber.

16. (canceled)

17. The device according to claim 1, wherein the flow generating means are adapted to realize circulation of the gas in the device including the tubular members of the humidity setting means, and comprise no more than a single unit for displacing the gas, such as a pump, or a (electrostatic) fan, or a compressor.

18. The device according to claim 1, wherein the at least one active tubular member of the humidity setting means comprises a replaceable cartridge.

19. The device for setting and controlling the humidity of a gas, comprising: flow generating means which are adapted to realize a flow of a gas in the device during operation thereof; humidity setting means which are adapted to perform a humidity setting action on gas flowing through the device during operation thereof, comprising at least one of 1) a humidity decreasing tubular member adapted to let gas flow through and decrease the humidity of the gas, and 2) a humidity increasing tubular member adapted to let gas flow through and increase the humidity of the gas; humidity sensing means for sensing the humidity of the gas in the device; and controlling means for controlling access to the tubular member of the humidity setting means, at both ends of the tubular member, in dependence of the humidity of the gas as sensed by the humidity sensing means during operation of the device and a reference value of the humidity.

20. The device according to claim 19, wherein the controlling means comprise valve means which are adapted to set an extent to which the tubular member of the humidity setting means is open, at both ends of the tubular member.

21. The device according to claim 20, wherein the valve means are adapted to set the extent to which the tubular member of the humidity setting means is open in a corresponding manner for both ends of the tubular member.

22. The device according to claim 19, wherein the flow generating means are adapted to realize circulation of the gas in the device including the tubular member of the humidity setting means, and comprise no more than a single unit for displacing the gas, such as a pump, or a (electrostatic) fan, or a compressor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further explained on the basis of the following description of an embodiment of a device for setting and controlling the humidity of a gas, with reference to the drawing, in which equal reference signs indicate equal or similar components, and in which:

[0022] FIG. 1 diagrammatically shows a perspective view of a first embodiment of a device according to the invention for setting and controlling the humidity of a gas, wherein components are depicted in a transparent fashion in order to provide a complete view of the various components of the device, and wherein a possible flow of gas through the device is indicated by means of arrows;

[0023] FIG. 2 diagrammatically shows a perspective view of a plate valve which may be part of the device according to the invention, wherein three possible positions of the valve are depicted, and wherein flows of gas through the valve in the various positions are indicated by means of arrows; and

[0024] FIG. 3 diagrammatically shows a perspective view of a second embodiment of a device according to the invention for setting and controlling the humidity of a gas, wherein components are depicted in a transparent fashion in order to provide a complete view of the various components of the device, and wherein a possible flow of gas through the device is indicated by means of arrows.

DETAILED DESCRIPTION OF THE INVENTION

[0025] FIG. 1 shows a first embodiment of a device 1 according to the invention for setting and controlling the humidity of a gas. The device 1 is suitable to be used for supplying a gas in situations in which it is important for the humidity of the gas to be exactly at a predetermined value. Examples of such situations comprise calibration of humidity probes and research performed under controlled conditions. The gas may be air, which does not alter the fact the device 1 is capable of handling every other possible type of gas as well.

[0026] The device 1 comprises a measuring chamber 10, and openings 11, 12 in a wall 13 thereof, which openings 11, 12 are adapted to let pass a flow of gas to and from the measuring chamber 10, respectively, and which are used as inlet and outlet, respectively, of the measuring chamber 10 during operation of the device 1. In the shown example, a preferred positioning of the openings 11, 12 is shown, in which the openings 11, 12 are arranged in line with each other. Such arrangement is preferred in order to promote a smooth gas flow between the openings 11, 12, through the measuring chamber 10, with a minimum of noise, but such arrangement is not essential within the framework of the invention.

[0027] For the purpose of putting gas in motion in the device 1, i.e. generating a gas flow, the device 1 comprises suitable flow generating means such as a pump 14. In the shown example, the pump 14 is arranged near an opening which is indicated by reference numeral 11 in FIG. 1, and which, for the sake of clarity, will be referred to as inlet 11 in the following, whereas the other opening will be referred to as outlet 12, which does not alter the fact that the pump 14 may as well be operated such that the first opening 11 is used as outlet and the latter opening 12 is used as inlet. Within the framework of the invention, other positions of the pump 14 are feasible, including a position near the latter opening 12, as long as the pump 14 is capable of generating a gas flow through the device 1 including the measuring chamber 10, between the openings 11, 12.

[0028] For the purpose of performing the function of setting the humidity of gas flowing through the device 1 when the device 1 is operated, the device 1 is equipped with a humidity setting unit 20, which is arranged between the inlet 11 and the outlet 12 in the shown example. In particular, the humidity setting unit 20 is adapted to dry the gas, humidify the gas, or leave the humidity level of the gas unamended, depending on the requirements of a particular situation. To this end, the humidity setting unit 20 comprises a number of tubular members 21, 22, 23. In the shown example, two active tubular members 21, 23, i.e. tubular members 21, 23 which are adapted to influence the humidity of the gas, are situated in the humidity setting unit 20, namely a humidity decreasing tubular member 21, which will hereinafter be referred to as drying member 21, and a humidity increasing tubular member 23, which will hereinafter be referred to as humidifying member 23. Furthermore, in the shown example, one inactive tubular member 22, i.e. a tubular member 22 which is adapted to just let the gas flow through without influencing the humidity of the gas, is situated in the humidity setting unit 20. The inactive tubular member 22 will hereinafter be referred to as inactive member 22.

[0029] The humidity setting unit 20 may comprise more than just one drying member 21, just one inactive member 22, and just one humidifying member 23. An advantage of having only three members 21, 22, 23, one of each possible type, is that the device 1 can be compact and small, so that the device 1 can be easily transported to any possible site. In the shown example, the three members 21, 22, 23 are arranged such as to extend parallel to each other, at substantially the same level in the measuring chamber 10, in a row-like arrangement in which the inactive member 22 is arranged between the drying member 21 and the humidifying member 23. Although this arrangement of the three members 21, 22, 23 is preferred for reasons of having a smooth flow of gas in the measuring chamber 10 during operation of the device 1, this arrangement is not essential within the framework of the invention.

[0030] Both the drying member 21 and the humidifying member 23 are adapted to allow a flow of gas to pass therethrough. The drying member 21 may comprise a replaceable cartridge filled with dry air and a moisture absorbing material. Alternatively, the drying member 21 may have a separate opening which allows for replacing used-up moisture absorbing material by fresh moisture absorbing material. In any case, the drying member 21 is designed such that the humidity of gas passing through the drying member 21 during operation of the device 1 is decreased. In a similar manner, the humidifying member 23 may comprise a replaceable cartridge filled with humid air and a material capable of releasing moisture. Alternatively, the humidifying member 23 may have a separate opening which allows for replacing used-up moisture releasing material by fresh moisture releasing material. In any case, the humidifying member 23 is designed such that the humidity of gas passing through the humidifying member 23 during operation of the device 1 is increased. It suffices for the inactive member 22 to comprise nothing more than a simple tube.

[0031] Besides the humidity setting unit 20, the device 1 according to the invention comprises humidity sensing means such as a humidity probe 25 for sensing an actual value of the humidity of gas in the device 1. The humidity probe 25 or similar means can have any suitable position in the device 1, as long as the humidity sensing function of the probe 25 is not hindered. In the shown example, the humidity probe 25 is located closely to the humidity setting unit 20, at a position between the humidity setting unit 20 and the outlet 12.

[0032] For the purpose of realizing a condition of the device 1 in which the humidity of gas flowing through the measuring chamber 10 is put to a reference value by means of the humidity setting unit 20, the device 1 comprises controlling means for controlling access of gas to the members 21, 22, 23 of the humidity setting unit 20. Within the framework of the invention, the controlling means can have any suitable design. In the shown example, the controlling means comprise a control box 26 for receiving and interpreting information from the humidity probe 25 representing an actual value of the humidity of gas in the device 1, which has a memory or the like for storing a reference value of the humidity, and which is adapted to compare the actual value to the reference value. The device 1 may comprise a user interface (not shown) by means of which a user can set the reference value in the memory of the control box 26, so that it is possible to adapt the operation of the device 1 to any reference value as desired. Furthermore, in the shown example, the controlling means comprise a slide 30 and means 31 for driving the slide 30 such as to assume a position as determined by the control box 26. In the following, details of the slide 30 will be elucidated. It is noted that the slide 30 is just one of numerous possibilities in respect of means for distributing a gas flow over the members 21, 22, 23 of the humidity setting unit 20. Hence, none of the details of the slide 30 as will be described in the following is essential within the framework of the invention.

[0033] The slide 30 extends through the measuring chamber 10 and comprises two plates 32, 33, namely an inlet plate 32 extending at a level close to the members 21, 22, 23 of the humidity setting unit 20, at an inlet side thereof, i.e. at an end of the members 21, 22, 23 facing the inlet 11, and an outlet plate 33 extending at a level close to the members 21, 22, 23, at an outlet side thereof, i.e. at an end of the members 21, 22, 23 facing the outlet 12. The plates 32, 33 are arranged in parallel, and are positioned such that longitudinal axes of the members 21, 22, 23 of the humidity setting unit 20 are perpendicular to the main surfaces of the plates 32, 33. The slide 30 is slidable in a direction which is both perpendicular to the longitudinal axes as mentioned and which coincides with a direction of the row-like arrangement of the members 21, 22, 23. This direction is indicated in FIG. 1 by means of arrows.

[0034] The slide 30 is adapted to allow gas to flow through the humidity setting unit 20 according to one of the following options: flow through the drying member 21 only, flow through the inactive member 22 only, flow through the humidifying member 23 only, flow through the drying member 21 and the inactive member 22, and flow through the humidifying member 23 and the inactive member 22, wherein the distribution of the total gas flow over a combination of members 21, 22, 23 is variable and can be set such as to be optimal under the circumstances of particular cases. In order to direct a gas flow as desired, the inlet plate 32 is provided with an opening 34, and the outlet plate 33 is provided with an opening 35 at a corresponding position. Advantageously, the dimensions of each of the openings 34, 35 correspond to the dimensions of the members 21, 22, 23 of the humidity setting unit 20 at the inlet side thereof and the outlet side thereof, respectively, as is the case in the shown example.

[0035] The device 1 according to the invention is operated in the following way. The device 1 is filled with a gas to be put to a predetermined humidity which is input as a reference value to the control box 26. The pump 14 is activated, as a result of which a flow of the gas is generated, wherein the gas is made to flow through the measuring chamber 10, from the inlet 11 to the outlet 12. In the process, the humidity probe 25 senses the actual value of the humidity of the gas and communicates this actual value to the control box 26. In the control box 26, a comparison is made between the actual value and the reference value. Depending on the outcome of the comparison, the control box 26 determines whether the drive means 31 need to be activated, and if so, how the drive means 31 need to be operated as far as distance and direction (extension or retraction) of the displacement to be realized of the slide 30 are concerned. The following situations may occur:

[0036] 1) The gas appears to be too wet, to such an extent that allowing all of the gas to flow through the drying member 21 would put the humidity of the gas to the reference value or to a value still higher than the reference value, in which situation the drive means 31 are operated to put the slide 30 to a position for letting the total flow of gas flow through the drying member 21 if the slide 30 is not already in the position as mentioned.

[0037] 2) The gas appears to be too wet, to a lesser extent than in the first situation, wherein it is possible to put the humidity of the gas to the reference value by directing one part of the total flow of gas through the drying member 21 and the other part of the total flow of gas through the inactive member 22. In this situation, the exact position of the slide 30 is determined such that the proper ratio between drying and no action can be realized. In case the slide 30 is at another position, the drive means 31 are operated to put the slide 30 to that exact position as determined in the control box 26.

[0038] 3) The humidity of the gas appears to be at the reference value, in which situation the drive means 31 are operated to put the slide 30 to a position for letting the total flow of gas flow through the inactive member 22 if the slide 30 is not already in the position as mentioned.

[0039] 4) The gas appears to be too dry, to such an extent that allowing all of the gas to flow through the humidifying member 23 would put the humidity of the gas to the reference value or to a value still lower than the reference value, in which situation the drive means 31 are operated to put the slide 30 to a position for letting the total flow of gas flow through the humidifying member 23 if the slide 30 is not already in the position as mentioned.

[0040] 5) The gas appears to be too dry, to a lesser extent than in the fourth situation, wherein it is possible to put the humidity of the gas to the reference value by directing one part of the total flow of gas through the humidifying member 23 and the other part of the total flow of gas through the inactive member 22. In this situation, the exact position of the slide 30 is determined such that the proper ratio between humidifying and no action can be realized. In case the slide 30 is at another position, the drive means 31 are operated to put the slide 30 to that exact position as determined in the control box 26.

[0041] Hence, the operation of the device 1 according to the invention is an ongoing process of sensing the actual value of humidity of a gas, making a comparison between the actual value and a reference value, and adjusting the position of the slide 30 if the outcome of the comparison and information regarding the actual position of the slide 30 indicates that it is necessary to do so in order to achieve that the reference value is realized/maintained. Once the process of setting the humidity of gas in the device 1 has started, it only takes a minimum of time before the reference value is achieved, due to the possibility to directly adapt the way in which the humidity setting unit 20 is enabled to treat the gas on the basis of measurements of the actual value of the humidity of the gas.

[0042] As has already been noted in the foregoing, the application of the slide 30 and the means 31 for driving the slide 30 is not essential within the framework of the present invention. The device 1 according to the invention may be equipped with another type of valve means for controlling the path to be followed by the gas through the humidity setting unit 20 and associated means for driving the valve means. An example of valve means which may be used in the device 1 instead of the slide 30 as shown in FIG. 1 is shown in FIG. 2. The design of the alternative valve means and the way in which the alternative valve means are operated will be explained in the following.

[0043] Like the slide 30, the alternative valve means are adapted to set an extent to which each of the members 21, 22, 23 of the humidity setting unit 20 is open at the inlet side and/or the outlet side thereof. In other words, like the slide 30, the alternative valve means are adapted to distribute a total flow of gas over the members 21, 22, 23. To that end, the alternative valve means comprise at least one plate valve 40 having two plates 41, 42, namely a basic plate 41 which has a fixed arrangement and a setting plate 42 which is arranged such as to slide along the basic plate 41. The basic plate 41 is provided with three openings 43, 44, 45 of a special design, arranged in a row-like fashion. A central opening 44 of the row has a rectangular shape, while the two openings 43, 45 which are present at either side of the central opening 44 are shaped like a beveled rectangle, wherein the bevel is present at the side facing the central opening 44. The setting plate 42 is provided with one rectangular opening 46 of which the dimensions correspond to the dimensions of the central opening 44 of the basic plate 41.

[0044] The plate valve 40 is preferably arranged such that each of the openings 43, 44, 45 of the basic plate 41 is associated with the members 21, 22, 23 of the humidity setting unit 20. In that case, the distribution of gas over the members 21, 22, 23 can be controlled by setting the position of the setting plate 42 with respect to the basic plate 41. For example, the setting plate 42 can be put to such a position that the opening 46 thereof coincides with the central opening 44 of the basic plate 41, as shown at the top side of FIG. 2. In that case, all of a gas flow is directed through the central opening 44, so that the situation in which the gas is not subjected to any humidity setting action is obtained. According to another option, as shown at the center of FIG. 2, the setting plate 42 is put to such a position that only part of a side opening 43, 45 and only part of the central opening 44 of the basic plate 41 are exposed. In that case, a total gas flow is divided in a gas flow through part of the side opening 43, 45 concerned and a gas flow through part of the central opening 44, so that the situation in which only part of the gas is subjected to a drying action or a humidifying action in order to achieve the reference value of the humidity of the gas is obtained. The ratio of the two gas flows is determined by the exact position of the setting plate 42 with respect to the basic plate 41, and is controlled on the basis of a comparison between an actual value of the humidity of the gas and a reference value, as explained earlier. According to yet another option, the setting plate 42 is put to such a position that the opening 46 thereof fully exposes one of the side openings 43, 45, as shown at the bottom side of FIG. 2. In that case, all of a gas flow is directed through the side opening 43, 45 concerned, so that the situation in which all of the gas is subjected to a drying action or a humidifying action is obtained.

[0045] An advantage of both the slide 30 as shown in FIG. 1 and the plate valve 40 as shown in FIG. 2 is that it is possible to have smooth, accurate and fast control of the humidity of the gas without a need for a complex construction. For the sake of completeness, it is noted that when two plate valves 40 are applied in the device 1 according to the invention, a first plate valve 40 is arranged at the inlet side of the humidity setting unit 20, and a second valve plate 40 is arranged at the outlet side of the humidity setting unit 20.

[0046] Optionally, the device 1 according to the invention comprises a tubular connection member 15 as shown in FIG. 1, connecting the outlet 12 of the measuring chamber 10 to the inlet 11. The connection member 15 is suitable to be used in situations in which it is desired to have an atmospherically closed circuit. This may be the case when the humidity of the gas in the device 1 is at the reference value and the gas is only made to flow through the inactive member 22 of the humidity setting unit 20. Also, applying the connection member 15 enables operation at different pressures and may save drying agent and/or water in the humidity setting unit 20.

[0047] FIG. 3 shows a second embodiment of a device 2 according to the invention for setting and controlling the humidity of a gas. The second embodiment resembles the first embodiment as described in the foregoing with reference to FIG. 1 to a large extent. However, a notable difference resides in the fact that the second embodiment comprises only one active tubular member 21, 23 besides the inactive member, wherein the active tubular member 21, 23 may be one of a drying member 21 and a humidifying member 23. In particular, the active tubular member 21, 23 may be adapted to receive and accommodate a cartridge containing a moisture absorbing material or a cartridge containing a material capable of releasing moisture, depending on whether the device 2 is intended to be used for drying a gas or humidifying a gas.

[0048] Apart from the fact that the device 2 comprises a single active tubular member 21, 23 instead of two different active tubular members 21, 23, the device 2 is of the same design as the device 1 as shown in FIG. 1, and, as a consequence thereof, is operated in a comparable manner. In particular, the device 2 as shown in FIG. 3 also comprises a measuring chamber 10 having two openings 11, 12 in a wall 13 thereof, a pump 14 for realizing a flow of gas in the device 2 during operation thereof, a humidity probe 25 for sensing an actual value of the humidity of gas in the device 2, a control box 26 for receiving and interpreting information from the humidity probe 25 representing an actual value of the humidity of gas in the device 2, and controlling means comprising a slide 30 and means 31 for driving the slide 30 such as to assume a position as determined by the control box 26.

[0049] It will be clear to a person skilled in the art that the scope of the present invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims.

[0050] For the sake of completeness, it is noted that the description of the capability of the device 1, 2 according to the invention to put the humidity of a gas to a reference value should be understood for its practical meaning, implying that it is possible to set the reference value with acceptable deviation tolerance. In many possible applications of the device 1, 2, it is often desirable to have a large humidity range, for example a range of 3% to 98%. Furthermore, it is noted that the fact that the members 21, 22, 23 of the humidity setting unit 20 are denoted as being tubular should be understood such as to mean nothing more than that the members 21, 22, 23 are provided with an entrance opening for letting in gas, an exit opening for letting out gas, and something like a circumferentially closed wall for directing gas from the entrance opening to the discharge opening. For example, the shape of the cross-section of the members 21, 22, 23 may be chosen freely within that general concept, although a circular shape is preferred in view of the associated smoothness of flow.

[0051] According to the invention, humidity setting means are applied which comprise at least one active tubular member 21, 23 and at least one inactive tubular member 22, arranged in parallel. In the example as described in the foregoing with reference to the figures, the humidity setting means comprise at least one active tubular member 21, 23 and one inactive tubular member 22, arranged in parallel. That does not alter the fact that within the framework of the invention, it is possible for the humidity setting means to comprise an assembly of tubular members in which there is not only a parallel arrangement of tubular members, but also an arrangement in series. For example, the humidity setting means may comprise an active tubular member 21, 23 and an inactive tubular member 22 which are arranged in parallel in the measuring chamber 10, and furthermore an active tubular member 21, 23 which is arranged in series with the two tubular members 21, 22, 23 mentioned first, in the measuring chamber 10, or outside of the measuring chamber 10, in a member connected to the measuring chamber 10 through one of the openings 11, 12 thereof. In such a case, a humidity decreasing tubular member 21 and an inactive tubular member 22 may be located in the measuring chamber 10, and a humidity increasing tubular member 23 may be present in a member serving as an inlet tube of the measuring chamber 10. During operation, the humidity of the gas is always increased by means of the humidity increasing tubular member 23, and the humidity of the gas is subsequently reduced in the measuring chamber 10 by means of the humidity decreasing tubular member 21 (or kept at the level as set by the humidity increasing tubular member 23 when the gas is made to pass through the inactive tubular member 22 only).

[0052] The aspect of controlling access to the tubular members 21, 22, 23 at both ends of the tubular members 21, 22, 23, at least in respect of the at least one active tubular member 21, 23 which is part of the humidity setting means of the device 1, 2 according to the invention is independent of the aspect of having at least one active tubular member 21, 23 and at least one inactive tubular member 22 in a parallel arrangement. Hence, the invention also relates to a device 1, 2 for setting and controlling the humidity of a gas, comprising: flow generating means 14 which are adapted to realize a flow of a gas in the device 1, 2 during operation thereof; humidity setting means which are adapted to perform a humidity setting action on gas flowing through the device 1, 2 during operation thereof, comprising at least one of 1) a humidity decreasing tubular member 21 adapted to let gas flow through and decrease the humidity of the gas, and 2) a humidity increasing tubular member 23 adapted to let gas flow through and increase the humidity of the gas; humidity sensing means 25 for sensing the humidity of the gas in the device 1, 2; and controlling means 26, 30, 31, 40 for controlling access to the tubular member 21, 23, at both ends of the tubular member 21, 23, in dependence of the humidity of the gas as sensed by the humidity sensing means 25 during operation of the device 1, 2 and a reference value of the humidity.

[0053] As explained in the foregoing, it is advantageous for the controlling means 26, 30, 31, 40 to comprise valve means 30, 40 which are adapted to set an extent to which the tubular member 21, 23 of the humidity setting means is open, at both ends of the tubular member 21, 23. Such valve means 30, 40 may be adapted to set the extent to which the tubular member 21, 23 of the humidity setting means is open in a corresponding manner for both ends of the tubular member 21, 23.

[0054] Due to the application of the valve means 30, 40 as mentioned, exchange of moisture with the tubular member 21, 23 in a direction which is opposite to the direction of the flow of the gas is minimized, as a result of which it is not necessary for the tubular member 21, 23 to be designed such as to realize a narrow passage and to be combined with a dedicated pump or the like for forcing the gas to flow through the narrow passage as is the case in conventional situations. Hence, it is possible for the flow generating means 14 to be adapted to realize circulation of the gas in the device 1, 2 including the tubular member 21, 23 and to comprise no more than a single unit for displacing the gas, such as a pump, or a (electrostatic) fan, or a compressor. As a result, there is no need for a complex design, and the noise generated during operation of the device 1, 2 is minimized.

[0055] The device 1, 2 according to the invention is intended for setting and controlling the humidity of a gas, as described in the foregoing. That does not alter the fact that the device 1, 2 is also suitable to be used in other applications, for example, for the purpose of setting and controlling the concentration of a certain component in a gas, such as oxygen or carbon dioxide, or a liquid, namely when the active tubular members 21, 23 are adapted to add or remove the component to or from the gas or liquid, and when the device is equipped with sensing means for sensing the concentration of the component in the gas or liquid in the device, and the controlling means are adapted to perform their controlling function in dependence of the concentration of the component in the gas or liquid as sensed by the sensing means during operation of the device and a reference value of the concentration. In such a case, the device is generalized as follows: device for setting and controlling the concentration of a component in a gas or liquid, comprising: flow generating means which are adapted to realize a flow of a gas or liquid in the device during operation thereof; composition setting means which are adapted to perform a composition setting action on gas or liquid flowing through the device during operation thereof, comprising at least two tubular members for the gas or liquid to flow through, arranged in parallel; sensing means for sensing the concentration of the component in the gas or liquid in the device; and controlling means for controlling access to the tubular members of the composition setting means, at least at one end of the tubular members, in dependence of the concentration of the component in the gas or liquid as sensed by the sensing means during operation of the device and a reference value of the concentration; wherein at least one of the tubular members of the composition setting means is an active tubular member comprising one of 1) a concentration decreasing tubular member adapted to let gas or liquid flow through and decrease the concentration of the component in the gas or liquid, and 2) a concentration increasing tubular member adapted to let gas or liquid flow through and increase the concentration of the component in the gas or liquid, and wherein at least one of the tubular members of the composition setting means is an inactive tubular member adapted to just let gas or liquid flow through without performing a composition setting action on the gas or liquid.

[0056] Also, in such a case, the device is generalized as follows: device for setting and controlling the concentration of a component in a gas or liquid, comprising: flow generating means which are adapted to realize a flow of a gas or liquid in the device during operation thereof; composition setting means which are adapted to perform a composition setting action on gas or liquid flowing through the device during operation thereof, comprising at least one of 1) a concentration decreasing tubular member adapted to let gas or liquid flow through and decrease the concentration of the component in the gas or liquid, and 2) a concentration increasing tubular member adapted to let gas or liquid flow through and increase the concentration of the component in the gas or liquid; sensing means for sensing the concentration of the component in the gas or liquid in the device; and controlling means for controlling access to the tubular member of the composition setting means, at both ends of the tubular member, in dependence of the concentration of the component in the gas or liquid as sensed by the sensing means during operation of the device and a reference value of the concentration.

[0057] The various details which are applicable to the device 1, 2 for setting and controlling the humidity of a gas, a number of which are defined in the dependent claims, are similarly applicable to the device when intended for setting and controlling the concentration of a certain component in a gas or liquid. In the latter case, the humidity decreasing tubular member is replaced by a concentration decreasing tubular member, the humidity increasing tubular member is replaced by a concentration increasing tubular member, the humidity sensing means are replaced by sensing means for sensing the concentration of the component in the gas or liquid in the device, and the controlling means which are adapted to perform their controlling function in dependence of the humidity of the gas as sensed by the sensing means during operation of the device and a reference value of the humidity are replaced by controlling means which are adapted to perform their controlling function in dependence of the concentration of the component in the gas or liquid as sensed by the sensing means during operation of the device and a reference value of the concentration. Furthermore, for the sake of completeness, it is noted that the term “fluid” can be used instead of the wording “gas or liquid”. Also, it is noted that the term “component” as used in the foregoing may be understood such as to include a portion of a total mixture having a certain value of energy such as heat.