WATER ANALYSIS DEVICE

Abstract

A water analysis device having a light source and a light detector for detecting an optical parameter of a water sample in a transparent measuring cell is disclosed. A ventilation circuit for ventilating a cell chamber is provided, wherein there is a differential pressure of at least 2.0 mbar between the cell chamber and the atmosphere when a ventilation pump is operated. The device housing forms the cell chamber which is fluidically sealed by a cover assembly. The cover assembly and the device housing have a mechanism that mimics the sealing action of a turn-lock fastener, such that the cover assembly can be secured to and/or released from the device housing by means of a rotational movement. The cover assembly and the device housing form an annular ring seal which is coaxial with the rotational movement and which is formed by an elastic sealing body having a circular sealing lip and a correspondingly circular shoulder seat on which the sealing lip is pressed due to the atmospheric differential pressure. Other aspects are disclosed and claimed.

Claims

1.-7. (canceled)

8. A water analysis device having a light source and a light detector which measures an optical parameter of a water sample in a transparent test cuvette, comprising: a cuvette chamber in which a test cuvette is arranged, a ventilation circuit which ventilates the cuvette chamber, wherein the ventilation circuit comprises the cuvette chamber, a ventilation pump downstream from the cuvette chamber, and a cuvette chamber air inlet downstream from the ventilation pump, wherein there is a differential pressure of at least 2.0 mbar in the cuvette chamber compared to the atmosphere when a ventilation pump is operated, and a cap arrangement and a device housing, wherein the device housing forms the cuvette chamber, which is fluidically closed by the cap arrangement, wherein the cap arrangement and the device housing have a screwlike mechanism, such that the cap arrangement can be locked and unlocked on the device housing by a turning motion, and the cap arrangement and the device housing form an annular ring seal that is coaxial to the turning motion, which is formed by an elastic sealing body with a circular sealing lip and a corresponding circular shoulder seat, upon which the sealing lip is pressed by the atmospheric differential pressure.

9. A water analysis device according to claim 8, wherein the locking mechanism is embodied as a bayonet lock.

10. A water analysis device according to claim 8, wherein the sealing body has a clamping ring, which is radially stretched onto a cylindrical support surface.

11. A water analysis device according to claim 9, wherein the sealing body has a clamping ring, which is radially stretched onto a cylindrical support surface.

12. A water analysis device according to claim 8, wherein the shoulder seat is convex and rounded when viewed in cross-section.

13. A water analysis device according to claim 9, wherein the shoulder seat is convex and rounded when viewed in cross-section.

14. A water analysis device according to claim 10, wherein the shoulder seat is convex and rounded when viewed in cross-section.

15. A water analysis device according to claim 11, wherein the shoulder seat is convex and rounded when viewed in cross-section.

16. A water analysis device according to claim 8, wherein the cuvette chamber air inlet has a pneumatic throttling element.

17. A water analysis device according to claim 9, wherein the cuvette chamber air inlet has a pneumatic throttling element.

18. A water analysis device according to claim 10, wherein the cuvette chamber air inlet has a pneumatic throttling element.

19. A water analysis device according to claim 11, wherein the cuvette chamber air inlet has a pneumatic throttling element.

20. A water analysis device according to claim 8, wherein the test cuvette is fixed to the cap arrangement.

21. A water analysis device according to claim 9, wherein the test cuvette is fixed to the cap arrangement.

22. A water analysis device according to claim 10, wherein the test cuvette is fixed to the cap arrangement.

23. A water analysis device according to claim 11, wherein the test cuvette is fixed to the cap arrangement.

24. A water analysis device according to claim 8, wherein the water analysis device is a process turbidity measurement device.

25. A water analysis device according to claim 9, wherein the water analysis device is a process turbidity measurement device.

26. A water analysis device according to claim 10, wherein the water analysis device is a process turbidity measurement device.

27. A water analysis device according to claim 8, wherein the water analysis device is a process turbidity measurement device.

Description

[0018] In the following, an exemplary embodiment of the invention is explained in further detail using the illustrations. The following are shown:

[0019] FIG. 1 a longitudinal section of a schematically shown water analysis device with a ventilation circuit in a device housing that is closed by a cap arrangement and

[0020] FIG. 2 an enlarged view of the ring seal between the cap arrangement and the device housing.

[0021] FIG. 1 shows a schematic view of a water analysis device 10, which is embodied as a process turbidity measurement device in the present example and serves the measurement and determination of the turbidity of a water sample 21 in the cuvette interior 21 of a transparent and cylindrical test cuvette 20, which preferably consists of transparent, colorless glass. The water analysis device 10 is a process device in the present example, but it can also be embodied as a laboratory device, in principle. The water analysis device is particularly suited for use in an environment with a high relative or absolute humidity.

[0022] The water analysis device 10 is essentially structurally composed of a device housing 14, a fluid-tight cap arrangement 12 that closes the device housing 14, a ventilation pump 50, and a drying unit 52 downstream from the ventilation pump 50, which are arranged outside of the device housing 14.

[0023] In the interior of the housing, the water analysis device 10 has a cuvette chamber 26 defined by a cup-shaped cuvette chamber housing 28 in which the test cuvette 20 is arranged and has a test chamber 30 which surrounds the exterior of the cuvette chamber housing 28 and is, for its part, externally limited by a cup-shaped test chamber housing 32. The test chamber housing 32, the cuvette chamber housing 28, and the test cuvette 20 are all cup-shaped embodiments.

[0024] The water analysis device 10 has a ventilation circuit for the ventilation of the housing interior in order to prevent condensation of humidity in the test chamber 30 and in the cuvette chamber 26 on the surfaces therein.

[0025] The process water analysis device 10 is equipped with a sample inlet 40 and a sample outlet 38, through which the water sample continuously or non-continuously flows into the cuvette interior 21 of the test cuvette 20 and then flows out of it. The test cuvette 20 is arranged within the cuvette chamber 26, which is continuously ventilated with dry air by the ventilation circuit.

[0026] The cuvette chamber 26 is essentially formed by the cup-shaped transparent cuvette chamber housing 28 and closed by the cap arrangement 12. The test cuvette 20 hangs on the cap arrangement 12 and is detachably fixed via a flange nut 22. An annular sealing ring 24 is arranged between the opening collar of the test cuvette 20 and the annular flange on the main body 18 of the cap arrangement 12 and ensures a fluid-tight sealing in this area.

[0027] The turbidity of a liquid is a measurement for the concentration of solid particles in the water sample 21. The turbidity is measured through the axial introduction of a light beam, which is emitted by a light source 23 axially along an optical longitudinal axis 13, into the test cuvette 20 and through the measurement of the light intensity of the light beam light scattered by the water sample 21 at an angle of 90 relative to the longitudinal axis 13, wherein the scattered light is collected by an annular optical element 44 and guided to an optical turbidity sensor 46. The annular optical element 44 and the turbidity sensor 46 are arranged in the test chamber 30.

[0028] The cap arrangement 12 essentially consists of an annular main cap 18 with a central opening 15 and a central cap 16 closing the central opening 15, which is screwed to the main cap 18.

[0029] The central cap 16 is formed by a cap body 16 made of opaque plastic and has the sample inlet 40 and sample outlet 38 on its exterior. The external sample inlet 40 leads to an internal sample inlet 36 through a conduit in the cap body 16, through which the water sample flows into the central opening 15 and into the cuvette interior 21. The external sample outlet 38 leads to an internal sample outlet 34 through a conduit in the cap body 16, through which the water sample flows out of the cuvette interior 21 through the central opening 15. An axial ring seal 42 is provided between the main cap 18 and the central cap 16 and ensures a fluid-tight sealing of the cuvette interior 21 against the external atmosphere.

[0030] The main cap 18 consists of a complex main cap body 18 made of opaque plastic and has, in particular, a locking mechanism 60 and a ring seal 70, both of which functionally interact with corresponding components on the device housing 14.

[0031] The locking mechanism 60 is embodied as a bayonet lock in the present example and has multiple axial bayonet teeth 64 on the cap side, each of which reaches behind a corresponding housing-side bayonet rib 62 in the locked closing position shown in FIG. 1. The locking mechanism 60 is embodied such that the opening and closing motion comprises an angle of only 15 to 30, but particularly preferably 20.

[0032] The ventilation circuit has the electric ventilation pump 50, the downstream passive drying unit 52 with molecular sieve, the pot-shaped test chamber 30, into which the air coming from the drying unit 52 flows through a device inlet opening 54 in the housing floor, the cuvette chamber 26, into which the air coming from the test chamber 30 flows through multiple air inlet openings 25 in the floor of the pot-shaped cuvette chamber housing 28, and a device air outlet 56, from which the drying air flows through a conduit to the ventilation pump 50.

[0033] In the air inlet openings 25 provided in the floor of the cuvette chamber housing 28, pneumatic throttling elements 25 are provided, which are formed by breathable membranes which are not, however, permeable to water molecules. The throttling elements 25 ensure a pressure drop in the one-digit to low three-digit millibar range when the ventilation pump 50 is running, such that there is a certain high pressure in the test chamber 30 compared to the atmospheric pressure PA and a certain low pressure in the cuvette chamber 26 compared to the atmosphere. In any case, when the ventilation pump 50 is running, the cuvette chamber pressure PI is lower than the atmospheric pressure PA outside of the water analysis device 10 by at least a few millibars.

[0034] The ring seal 70 is shown in detail in FIG. 2. It is essentially formed by a cap-side axial ring rib 74, a sealing body 70 fixed on the ring rib 74 with a circular sealing lip 78, and a housing-side circular and corresponding shoulder seat 72, upon which the flexible sealing lip 78 lies with its proximal lip surface 76. The shoulder seat 72 is convex and rounded when viewed in cross-section, as can be seen particularly well in FIG. 2. The radial size of the rounding is such that the full surface of the sealing lip 78 lies on the shoulder seat 72.

[0035] The elastic sealing body 70 essentially consists of a clamping ring 80, which is suspended and stretched with its proximal interior surface 77 onto a corresponding cylindrical distal support surface 75 of the ring rib 74, and the thin-lipped sealing lip 78. In the area of the ring seal 70, no grease of any kind is provided in order to improve the sealing effect, so the ring seal 70 is absolutely grease-free.

[0036] As long as the ventilation pump 50 is running, there is a low pressure in the cuvette chamber 26 compared to the atmospheric pressure PA, and there is a practically identical low pressure in the area of the circular shoulder seat 72 on the proximal lip surface 76 of the sealing lip 78. The full surface of the sealing lip 78 is hereby pressed onto the shoulder seat 72, whereby a very good fluid sealing is produced.

[0037] When the ventilation pump 50 is no longer running, more or less atmospheric pressure arises in the cuvette chamber 26 after a certain period of time, such that the sealing lip 78 only lies loosely on the shoulder seat 72. As a result, there is also no more static friction between the sealing lip 78 and the shoulder seat 72, such that the cap arrangement 12 can be held, turned in the direction of opening, and ultimately removed from the device housing 14 without any problems.

[0038] During the closing procedure, that is to say when the cap arrangement 12 is placed upon the device housing 14 and turned in the direction of closing, the ventilation pump 50 is turned off, such that it is also ensured during the closing procedure that the sealing lip 78 lies only loosely on the circular shoulder seat 72 and only negligible friction forces appear. As soon as the closing procedure is completed, the ventilation pump 50 can be turned on, such that a low pressure is generated in the cuvette chamber 26, whereupon the sealing lip 78 suctions itself to the shoulder seat 72.

[0039] If, during the measurement operation, there is a leak in the area of the ring seal 24 or the test cuvette 20 leaks, the liquid flowing into the cuvette chamber 26 with the high pressure can flow through the ring seal 70 without any problems, because here, the test chamber interior pressure PI is greater than the atmospheric pressure PA.

[0040] In this manner, the test sample liquids are prevented from flowing into other parts of the water analysis device 10 and triggering damage and disruption there.