WO2009092570A1

WO2009092570A1 - Titration device for continuous measuring of water hardness

Info

Publication number: WO2009092570A1
Application number: PCT/EP2009/000352
Authority: WO
Inventors: Jörg ZIMMERMANN; Rüdiger Neddermeier
Original assignee: Gebrüder Heyl Analysentechnik GmbH & Co. KG
Priority date: 2008-01-23
Filing date: 2009-01-21
Publication date: 2009-07-30
Also published as: DE102008005692B3

Abstract

The invention relates to a device for continuous titration, in particular for determining the water hardness of sample water, comprising: a) a sample receiving container for receiving the sample water, comprising a sample water outlet, b) an indicator container for receiving a liquid indicator, comprising a indicator outlet, c) a mixer and d) a measuring cell. The measuring cell comprises a sample mixing inlet connected via a sample mixture line to the sample mixture outlet of the mixer, a discharge, a light source, a photo cell and a measuring chamber, also comprising an inlet region and an outlet region, wherein the inlet region and outlet region are arranged in the measuring chamber such that the photometric measuring area between the light source and the photo cell is void-free.

Description

TITRATION DEVICE FOR CONTINUOUS MEASUREMENT OF HYDROPHONES

description

Background of the invention

For many industrial applications, it is necessary to continuously provide water of a certain quality. In particular, there are numerous applications where the concentration of calcium and magnesium carbonate ions, i. the water hardness, a certain limit may not exceed. Since the water supplied by the waterworks to industrial users usually exceeds this limit on the one hand and of varying quality on the other hand, water treatment plants are used to produce a water that meets the requirements. These water treatment plants usually include ion exchangers to lower the water hardness. Since the ion exchangers have a limited capacity, they must be regenerated in the event of exhaustion of this capacity. The temporal regeneration intervals are irregular and depend inter alia on the amount of treated water and the hardness of the water supplied by the water supply.

In order to avoid disturbances in industrial applications due to poor water quality, the treated water is regularly examined for its properties, in particular water hardness.

For this purpose, known from the prior art devices that regularly, ie discontinuously, automatically remove samples from a water pipe and then examine them. An important test method is the titration of the water samples by means of an indicator and a titration solution. Due to the water hardness thus determined, for example, the time for regeneration of the ion exchanger can be determined early.

A disadvantage of these devices, on the one hand, that the sampling of water from the water pipe is quite expensive. On the other hand, the titration for water hardness determination is technically complicated, whereby the corresponding devices are costly and maintenance-intensive. In addition, this effort is unnecessary for many applications, since it is only necessary to keep the hardness of the water below a certain limit.

In view of this prior art, it is an object of the invention to provide a cost-effective, reliable and low-maintenance device, which makes it possible to continuously monitor compliance with a predetermined limit of a water parameter, in particular the water hardness.

This object is achieved by a device for continuous titration of a sample water, in particular for determining the water hardness, with the features of claim 1. Preferred embodiments are subject of the dependent claims.

One aspect of the invention relates to a device for continuous, in particular unpressurised or overpressure, titration, in particular for determining the water hardness, a sample water, comprising: a sample receptacle for receiving the sample water, comprising a sample water outlet, an indicator container for receiving a liquid indicator, comprising a Indicator outlet, a mixer and a measuring cell.

The mixer comprises a sample water inlet connected by a sample water line to the sample water outlet of the sample receiver, an indicator inlet passing through an indicator line to the indicator outlet of the sample receiver

Indicator tank is connected and a Probegemischauslaß, wherein the Sample water inlet, the indicator inlet and the sample mixture outlet are hydraulically connected to each other, ie that a fluid, in particular water, can flow between them.

The measuring cell comprises a sample mixing inlet which is connected by a sample mixing line to the sample mixture outlet of the mixer, an outflow, a light source, a photocell and a measuring chamber, further comprising an inlet region and an outlet region, wherein the inlet and outlet regions are arranged in the measuring chamber in that the photometric measuring range between the light source and the photocell is bubble-free.

The perpendicular direction Z is perpendicular to a geoid, i. perpendicular to a parallel to the normal zero equipotential surface of the Earth's gravity field, and antiparallel to the gravitational acceleration, i. pointing away from the center of the earth. Furthermore, the perpendicular position definitions "above" or "above" and "below" or "below" are defined by the perpendicular direction Z, such that a position B which is in the perpendicular direction when viewed from a position A is above the position A or is above. In the reverse position is the position A below the position B or below. Thus, the subsequent use of these terms in the context of the application is defined.

For the purposes of the invention, a light source is understood to be a source of electromagnetic radiation which does not necessarily have to be in the range of visible light. In particular, the light source can emit infrared or ultraviolet radiation.

Accordingly, a photocell is understood to mean a cell which is sensitive at least in a region of the electromagnetic radiation which is emitted by the light source in such a way that it measurably changes its electrical properties.

The sample receptacle is for continuous non-pressure absorption of Sample water designed from a tap. An optionally present at the tap overpressure of the sample water against the hydrostatic pressure is relaxed or not present in the sample receptacle. In particular, the sample receptacle has an overflow over which excess sample water from the sample receptacle flows into a drain. This ensures that advantageously only the corresponding due to gravity hydrostatic pressure prevails. This is advantageous because the hydrostatic pressure depends not only on the construction of the titration but not on the pressure conditions in the water-supplying line. The sample water contained in the titration device is therefore pressureless or overpressure. Advantageously, the material of the titration device can be designed to be weaker in accordance with the hydrostatic pressure conditions than in titration devices whose sample water is under overpressure during normal use.

Particularly preferred is a downwardly or to the sample water outlet towards tapered or funnel-shaped design of the sample receiving container. More preferably, the sample water outlet comprises a filter, for example a sieve, which filters solid particles from the sample water in order to prevent clogging of the downstream components or lines.

Advantageously, the mixing ratios between sample water and indicator obtained in the mixer result solely from the radii of the supply lines and their lengths and the height difference to be overcome, ie the hydrostatic pressure applied in the respective line. Assuming a laminar flow of the liquids involved, the corresponding calculations can be made by means of the law of Hagen-Poiseuille. Advantageously, the mixing ratio is determined by the construction of the titration device, so that no moving parts, in particular no pumps, valves or other control devices, are necessary. Preferably, the titration device is free of pumps and / or valves that are designed to sample water and / or indicator promote or influence the mixing ratio between sample water and indicator. In this context, the term "continuous titration" means in particular that the transport of the sample water or of the indicator takes place exclusively on account of the hydrostatic pressure or the gravitation, ie that a titration takes place as long as there is sufficient hydrostatic pressure in the titration device Therefore, the titration device is particularly wear-free, reliable and requires little maintenance, so that possible incorrect settings by the user are also advantageously excluded.

Advantageously, the measuring cell, in particular the measuring chamber in the measuring cell, is designed and arranged such that the gases outgassing from the sample water, first disturb the measurement in the measuring chamber not by scattering on the gas bubble surface and secondly the flow through the titration by not one Hinder accumulation of gas bubbles. For this purpose, it is necessary that the photometric measuring range between the light source and the photocell is free of bubbles. The photometric measuring range comprises the volume of the measuring chamber whose optical properties have an influence on the measurement carried out by means of the photocell. That the photometric measuring range comprises the volume of the measuring chamber, which is penetrated by the light rays which subsequently strike the photocell. In particular, the light source and the photocell may have flat circular or rectangular outlets or inlet openings, so that the photometric measuring area can be embodied correspondingly in the shape of a truncated cone or a truncated pyramid.

In particular, the titration device comprises an evaluation, which can be advantageously carried out very easily. Since, for the reasons described above, the titration device advantageously has no moving parts, in particular no controllable or controllable parts, the functionality of the evaluation electronics can depend on the supply of the light source Limit evaluation of the voltage or the voltage drop across the photocell or the current generated by the photocell and in particular to the control of a signaling device.

Preferably, the measuring chamber extends within the measuring cell substantially along a direction Mp ₁ wherein the direction Mp and the direction of solder Z include an angle ß greater than 0 degrees or 0 and less than 90 degrees or π / 2. The term "essentially" with reference to directions here and in the following description should be understood to mean that the indicated degrees can differ in particular by less than ± 15 degrees from the indicated value, preferably by less than ± 10 degrees, less than ± 5 degrees, and more preferably less than ± 1 degree.

Particularly preferably, the angle β is in a range of about 10 ° to 80 °, more preferably in a range of about 30 ° to 60 ° or about 40 ° to 50 ° and in particular β is about 45 ° or π / 4. The term "about" here and in the following description is to be understood as meaning that the dimensions and values given may in particular deviate from the stated value by less than ± 50%, preferably by less than ± 30%, less than ± 20%. , less than ± 10%, less than ± 5%, and in particular less than ± 1% Advantageously, resulting gas bubbles collect by their buoyancy at the upper limit of the

Measuring chamber and are due to the special arrangement, i. the corresponding choice of the angle ß, along the upper boundary of the

Measuring chamber in the direction of Mp, in particular in the direction of the outlet, displaced and discharged from the measuring chamber.

Preferably, the sample mixture line is at least partially formed as a reaction coil, ie, helical. The turbulences resulting from the different path lengths, depending on whether the sample mixture flows along the spiral inner side or the spiral outer side, advantageously lead to a very good mixing of the individual components of the Sample mixture. The reaction coil may preferably be formed as a flexible tube or rigid tube. In particular, the tube or the tube of the reaction coil made of sufficiently chemically resistant and fluid-tight plastics, such as rubber, polypropylene, polyethylene, polyvinyl chloride or polycarbonate exist. Alternatively, the reaction coil may be formed as a tube made of glass or stainless steel. Advantageously, a reaction coil designed as a tube, in particular as a stainless steel tube, has an increased mechanical stability.

Preferably, the measuring chamber is cylindrical, so that the cylinder axis defines the direction Mp. This shape of the measuring chamber is advantageously particularly easy to manufacture and a cylindrical light source and / or photocell is particularly easy to mount and center on or in the measuring chamber in this case.

Preferably, the measuring chamber is cuboid, so that the longitudinal axis of the cuboid determines the direction Mp.

The outflow of the measuring chamber is preferably arranged above the sample mixture inlet of the measuring chamber. As a result, advantageously contained in the measuring chamber gas displaced by buoyancy in the direction of the outlet and escapes there together with the effluent sample mixture.

Preferably, the rectilinear connection of the light source with the photocell coincides substantially with the direction Mp. In this case, advantageously, the distance of the light through the sample mixture located in the measuring chamber is maximum. As a result, the extinction effect of the sample mixture is maximum and the other edge effects are minimal.

Preferably, at least one color filter is arranged in the beam path between the light source and the photocell. Alternatively, the light source preferably radiates a colored light, ie a light whose amplitude spectrum or power density spectrum is not constant in the wavelength or frequency range. Advantageously, this is the amplitude spectrum or the color of the light which is transmitted through the measuring chamber and registered by the photocell in the wavelength or frequency range in particular one or two sides limited, ie in particular the power density spectrum for wavelengths is smaller than a lower limit wavelength λmin and / or greater than an upper cut-off wavelength λ _ma χ attenuated by more than 20 dB, preferably more than 40 dB from the maximum of the power density spectrum. Depending on the color of the sample mixture then takes place a more or less strong extinction of the light of the light source. The photocell registered accordingly a more or less large incident light intensity, whereby the measurable between two contacts of the photocell voltage or the current generated by the photocell is correspondingly larger or smaller.

Preferably, the color of the light source or that of the color filter substantially corresponds to the color of the liquid indicator.

Alternatively, the color of the light source or the color filter preferably corresponds substantially to the complementary color of the liquid indicator. Advantageously, the voltage difference measurable at the photocell becomes maximum when the light source emits a colored light which substantially corresponds to the color or the complementary color of the liquid indicator. Particularly advantageously, the color change of the indicator takes place between two mutually complementary colors.

Preferably, a light guide is arranged in the beam path between the light source and the photocell, which protrudes into the measuring chamber. Particularly preferably, the light guide is made of glass. Further preferred is the light guide cylindrical or frustoconical. The light guide can be fastened directly or indirectly to an end face of the measuring chamber, in particular by means of an adhesive. One end of the light guide protrudes into the measuring chamber, while at the opposite end of the light guide, the light source is arranged. The light emitted by the light source is radiated through the light guide into the measuring chamber. Advantageously, the glass rod is chemically inert and resistant to staining and discoloration. Further advantageously, it is prevented by the intrusion of the light guide that gas bubbles, which accumulate on the front side of the measuring chamber, influence the light beam.

Preferably, the light source is a light emitting diode. This advantageously results in a lower design effort, a lower energy consumption and an increased life of the light source. This results in increased reliability and simpler design of the entire titration device.

Preferably, the radius of the indicator line is less than the radius of the sample water line so that the ratio of indicator flow rate in the indicator line to sample water flow rate in the sample water line is less than 1:10.

Preferably, the sample water inlet and the sample mixture outlet of the mixer are connected to each other substantially rectilinearly along a direction M _w through a mixer conduit. Advantageously, the rectilinear mixer line can be formed through a pipe or through a hole in a block of material.

Preferably, the mixer conduit has an inlet, the inlet and the indicator inlet being connected substantially rectilinearly along a direction Mj by an admixing conduit. Advantageously, the rectilinear admixing line can be formed through a pipe or through a hole in a block of material. Preferably, the direction M _w and the direction Mj include an angle α greater than 0 degrees and 0 and less than 90 degrees and π / 2, respectively. In particular, α is in one

Range of about 10 ° to 80 °, about 30 ° to 60 ° or about 40 ° to 50 ° and more preferably α is about 45 ° or π / 4. Advantageously, thereby a displacement of the indicator can be prevented back into the admixing, which by the

Pressure of the sample water in the mixer line is conditional. Particularly advantageously, the angle α is selected such that at the inlet of the mixer line, a negative pressure in the indicator line is formed, so that the indicator can be safely supplied.

Preferably, the sum of the line lengths of the admixing line and the indicator line is smaller than the capillary rise in these lines. Advantageously, then flows due to the capillary rise in the indicator line no further indicator due to gravity in the mixer, if it falls dry due to an interruption of the sample water supply and is filled with air.

Preferably, the sample receptacle or the sample water line has a sample water shortage detection device. In particular, the sample water lack detection device may comprise two electrodes which are electrically connected to each other via the sample water. Alternatively, the sample water deficiency detection device may be implemented as a light barrier. In the case of an interrupted sample water supply, the electrical contact may be interrupted or the beam of the light barrier may be deflected. Advantageously, thereby the supply interruption is detected and signaled.

The indicator container or the indicator line preferably has an indicator lack recognition device. The indicator deficiency recognition device can be designed, in particular, analogously to the sample water defect detection device. Advantageously, both of the detection devices described above trigger a signal to alert the user to the respective one of the two Malfunction, ie a sample water or indicator shortage, to indicate. This may include an optical, an acoustic or an electronic signal.

Preferably, the indicator container has a Indikatorauslaßvorrichtung to keep the applied pressure at the Indikatorauslaß constant regardless of the level of the indicator.

Preferably, the mixer is monolithic. This advantageously leads to increased stability and reliability as well as to a simple interchangeability of this component of the titration device.

Preferably, the sample receptacle, the sample water line and the mixer are monolithic. Advantageously, this reduces the number of items to be assembled. In particular, the length and diameter of the sample water line are well defined by a monolithic design of these components.

Hereinafter, preferred embodiments will be described by way of example with reference to the accompanying drawings.

FIG. 1 shows a preferred embodiment of a titration device.

Figure 2 shows in a detail view a mixer 30 of the preferred

Embodiment of the titration device.

FIG. 3 shows in a detail view a measuring cell 40 of the preferred embodiment of the titration device.

FIG. 4 shows in a detail view a measuring cell 40 in a further preferred embodiment, FIG. 5 shows in a detailed view a preferred embodiment of a

Light source receptacle 47a.

FIG. 1 shows a preferred embodiment of a titration device 1 for continuous determination of water hardness by complex-method titration. The titration device 1 comprises a sample receptacle 10 for continuously receiving sample water 2 from a tapping point 12. The sample receptacle 10 has a sample water outlet 14 and an overflow 16 located above the sample water outlet 14. Through the overflow 16 excess sample water 2 flows from the sample receptacle 10 in a sequence 60. The height difference .DELTA.h _a between the sample water outlet 14 and the overflow 16 determines the maximum water pressure p _a , which occurs at the sample water outlet 14. The minimum water pressure p _a is zero in the event that the sample receptacle 10 is empty.

In order to achieve the most constant possible water pressure p _a at the sample water outlet 14, it is therefore expedient to select the height difference Δh _a as small as possible. Alternatively, the inflow rate from the tap 12 may be selected to be greater than the effluent rate from the sample water outlet 14 so that always a portion of the inflow flows into the drain 60 via the overflow. As a result, the height difference Δh _a and thus the water pressure p _a at the sample water outlet 14 is constant.

In order to ensure a continuous provision of sample water at the sample water outlet 14, it is expedient to choose the volume V _{a of} the sample receptacle as large as possible. On the other hand, the requirement of mixing

Proof water to prevent which at different times t | and t2 from the

Tap 12 was tapped to detect a change in the sample water in a timely manner. The volume V _{a of} the sample receptacle may vary depending on the required maximum time delay Δt = t2 ~ t- | [in s] and the sample water flow rate v = dV / dt [in cm ^ / s] can be calculated by the formula V _a <v Δt.

The interior of the sample receiving container 10 is preferably tapered towards the bottom or to the sample water outlet 14 or funnel-shaped.

Preferably, a filter is disposed on the sample water outlet 14, the solid particles filtered from the sample water to prevent clogging of the downstream components or lines. At the sample water outlet 14, a sample water line 18 is arranged, which connects the sample receiving container 10 with a mixer 30. The sample water line 18 is preferably a hose line, which may be made in particular of Teflon (PTFE). Preferably, a sample water shortage recognition device 19 can be arranged in or on the sample receptacle 10. For example, the sample water deficiency detection device may include two electrodes that are electrically connected to each other via the sample water 2 when the sample receptacle 10 is sufficiently filled. Alternatively, the sample water deficiency detection device 19 may be disposed on the sample water line 18. For this purpose, in particular in a region of the sample water line 18, the two electrodes could be arranged opposite one another, which are electrically connected to one another via the sample water 2 when the sample water line 18 is filled. The sample water deficiency recognition device 19 could, however, also be designed as a light barrier with sample water line 18 arranged therebetween, wherein the light barrier registers the presence or absence of the sample water 2 in the sample water line 18.

The embodiment shown in Fig. 1 further comprises an indicator tank 20 for a liquid indicator 3. The indicator tank 20 comprises an indicator outlet 22 with an indicator outlet 24. The indicator outlet 22 ensures by its construction that the pressure of the indicator at the indicator outlet 24 is constant. This can be achieved, for example, in that the indicator container 20 has only an opening with an upstream storage area to the outlet of the liquid indicator 3 and at the same time to the inlet of air at the bottom of which the indicator 3 is present and thus an ingress of air in the rule prevented. If the filling level of the liquid indicator 3 in the storage area drops below a certain level, a certain volume of air can penetrate into the indicator container 20 and an equal volume indicator 3 exits into the storage area until the opening is closed again by indicator 3. This exemplary embodiment of the indicator outlet 22 is well known as a birdbath. Different filling levels of the indicator 3 in the indicator container 20 are thereby compensated. At the indicator outlet 24, an indicator line 28 is arranged, which connects the indicator container 20 with the mixer 30. The indicator line 28 is preferably a hose line, which may be made in particular of Teflon (PTFE).

Preferably, an indicator mangle detection device 26 may be disposed in or on the indicator outlet 22 for detecting an indicator shortage. The indicator deficiency recognition device 26 may for example comprise two electrodes, which are electrically connected to each other via the indicator 3 when the indicator container 20 is sufficiently filled. Alternatively, the indicator lack recognition device 26 may be disposed on the indicator line 28. For this purpose, in particular in a region of the indicator line 28, the two electrodes could be arranged opposite each other, which are electrically connected to one another via the indicator 3 when the indicator line 28 is filled. The indicator lack recognition device 26 could, however, also be designed as a light barrier with an indicator line 28 arranged therebetween, the light barrier registering the presence or absence of the indicator 3 in the indicator line 28.

The mixer 30 has a sample water inlet 31 connected to the sample water line 18, and one connected to the indicator line 28

Indicator inlet 32 and a sample mixture outlet 34 on. The sample water inlet

31, the indicator inlet 32 and the sample mixture outlet 34 are within the

Mischers 30 hydraulically connected. Preferably, the sample water inlet 31 and the sample mixture outlet 34 are connected in a straight line to each other by a mixer pipe 33 which extends substantially along a direction M _w . Further preferably, the mixer line 33 has an inlet 35, wherein the inlet 35th with the indicator inlet 32, in particular in a straight line, is connected by a Zumischleitung 36. The admixing line 36 extends, in particular in the area contacting the inlet 35, essentially along one direction Mj. In particular, the mixer 30 may be formed as a T-piece. Preferably, the directions M _w and Mj include an angle α different from 90 ° or π / 2, respectively. Preferably, α is in a range of about 10 ° to 80 °, more preferably in a range of about 30 ° to 60 °, or about 40 ° to 50 °, and more preferably α is about 45 ° or π / 4.

The mixing ratios between sample water 2 and indicator 3 achieved in the mixer 30 result solely from the radii of the feed lines 18 and 28 and their lengths and the height difference Δh to be overcome. From the law of Hagen-Poiseuille, the following relationship for a laminar flow of a liquid in a cylindrical conduit is given, assuming a flow which is caused solely by gravity, that is to say without pressure.

Here, p is the density and η the viscosity of the liquid (in the specific case of the sample water 2 or the indicator 3), R the radius, I the length and Δh the height difference of the line (in the specific case of the sample water line 18 or the indicator line 28) and dV / dt is the flow rate occurring in the line.

Table 1: Exemplary calculations to estimate the flow rates occurring in different non-pressurized lines for different liquids.

Preferably, the consumption of indicator solution should be kept as low as possible in order to maximize the refill intervals for the indicator 3 and thus the maintenance-free operating time of the titration device 1. Therefore, the ratio of indicator flow rate in the indicator line 28 and sample water flow rate in the sample water line 18 is preferably less than 1:10, more preferably 1:50, 1: 100 or 1: 500. Most preferably, the ratio is less than 1: 1000.

In this embodiment, the radius of the sample water conduit 18 is preferably about 0.25 mm to about 1 mm, more preferably 0.5 mm or 0.75 mm, and the radius of the indicator conduit 28 at least in regions preferably about 0.1 mm to about 0, 5 mm, more preferably 0.25 mm. A region of the indicator line 28 arranged close to the indicator container 20 has a larger radius of preferably 0.75 mm. Both line areas are preferably connected to each other by an adapter piece 29. The indicator 3 preferably has a viscosity increased by about a factor of 10 relative to the sample water 2. This results in particular in a mixing ratio of about 1 part indicator to 1000 parts of sample water.

Another effect to be considered in sufficiently thin conduits is the capillarity that occurs, i. the capillary slope Δk in the line, which is given by the equation

M = ^

Rpg calculates. Here, p is the density and σ the specific surface tension of the liquid (in the specific case of the sample water 2 or the indicator 3), R the Radius of the line (in the specific case of the sample water line 18 or the indicator line 28), g the acceleration due to gravity (9.81 kg m / s2) and Δk is the capillary rise occurring in the line. For aqueous solutions and the conductor radii R used in Table 1, the capillary increases listed in Table 2 result.

Table 2: Exemplary calculations to estimate the occurring capillary rises in lines with different radii.

In this embodiment, the length of indicator line 28 is preferably less than 60 mm. Since the radius of the indicator line 28 is particularly preferably 0.25 mm, in particular, a capillary rise of about 60 mm results. Should the mixer 30 fall dry due to an interruption of the sample water supply and be filled with air, advantageously no further indicator 3 would flow into the mixer 30 due to the capillary rise.

A reaction coil 38 is connected to the sample mixture outlet 34 via a sample mixing line 37. The reaction coil 38 is a spiral wound line. In this embodiment, the sample mixture line 37 and the reaction coil 38 are integrally formed in the form of a tube having an inner diameter of preferably about 0.25 mm to about 1, 5 mm, more preferably about 0.75 mm and in particular about 1 mm. The reaction coil 38 is thereby formed by a preferably about 0.2 m to about 1 m, particularly preferably about 0.3 m to about 0.8 m and in particular an approximately 0.5 m long region of the tube or tube, the to a cylindrical core of preferably about 5 mm to about 100 mm, especially preferably about 5 mm to 50 mm, and in particular about 12 mm or about 20 mm in diameter is wound, so that preferably 3 to 30, particularly preferably 5 to 15, and in particular about 7 turns are formed.

It is understood that the tube or tube of the reaction coil 38 may consist of sufficiently chemically resistant and fluid-tight plastics, such as rubber, polypropylene, polyethylene, polyvinyl chloride or polycarbonate. Alternatively, the reaction coil 38 may be formed of a glass or stainless steel tube.

This embodiment further comprises a measuring cell 40, which has a sample mixing inlet 41, a measuring chamber 42 and an outflow 43. The sample mixture inlet 41 is connected to the sample mixture line 37. The preferred construction of the measuring cell 40 is shown in FIG.

In the region of the end faces of the measuring chamber 42, a light source 47 and a photocell 48 are arranged so that the light of the light source irradiates the measuring chamber 42 with the sample mixture 4 therein and then strikes the photocell 48. The light beams emitted by the light source 47 preferably propagate through the measuring chamber 42 along the direction Mp. Depending on the intensity of the extinction and / or scattering of the light rays through the medium located in the measuring chamber 42, a more or less large light intensity impinges on the photocell 48, whereby its electrical properties are changed. This change in electrical properties is detected by the transmitter 50 and evaluated accordingly.

The effluent 43 is finally connected to a drain 60. Between the outflow 43 and the outlet 60 or parallel thereto, a suction device 62 can be connected, which serves for the initial venting of the titration device 1.

FIG. 2 shows in a detail view a preferred embodiment of the mixer 30. The mixer 30 has a test water inlet 31 connectable to the sample water line 18, an indicator inlet 32 connectable to the indicator line 28, and a sample mixture outlet 34.

The sample water inlet 31 and the sample mixture outlet 34 are rectilinearly connected to each other by a mixer pipe 33 extending along the direction M _w . The inlet 35 of the mixer line 33 is connected to the indicator inlet 32 in a straight line along the direction Mj through the admixing line 36. The directions M _w and Mj include an angle α of about 45 ° and π / 4, respectively. As a result, it is advantageously possible to prevent the indicator from being forced back into the admixing line 36 due to the pressure of the sample water in the mixer line 33.

In this embodiment, both the conduits 33 and 36 and the sample water inlet 31, the indicator inlet 32 and the sample mixture outlet 34 are monolithically made of a block of material. The block of material in this embodiment is made of a polymer and is therefore advantageously easy to work, light and corrosion resistant. The mixer 30 has a diameter or an edge length D | \ / | of about 30 mm (depending on whether the mixer is cylindrical or cuboid) and a longitudinal extent HM of about 25 to about 35 mm. The mixer line 33 is designed as a bore with a diameter of about 1, 0mm and the admixing line 36 is formed as a bore with a diameter of about 0.5 mm. The sample water inlet 31, the indicator inlet 32 and the sample mixture outlet 34 are each formed as 1/4 "threads UNF G28 or as threads 10-32 UNF Alternatively, the inlets and outlets can also be designed as nozzles, clamping or screw connections.

FIG. 3 shows in a detail view a preferred embodiment of the measuring cell

40, which has a sample mixing inlet 41, a measuring chamber 42 and an outflow 43. An inlet region 44a of the measuring chamber 42 is hydraulically connected via a line 44 to the sample mixture inlet 41. An outlet portion 45a of Measuring chamber 42 is hydraulically connected via a line 45 to the outlet 43. The measuring chamber extends substantially linearly between the inlet portion 44a and outlet portion 45a along a direction M _p. In this case, the direction M _p with the perpendicular direction Z includes an angle β which is different from 90 ° or π / 2. Preferably, β is in a range of about 10 ° to about 80 °, more preferably in a range of about 30 ° to about 60 °, or about 40 ° to about 50 °, and more preferably β is about 45 ° or π / 4.

In the region of the front side 45b of the measuring chamber 42 is a light source 47 and in the region of the end face 44b of the measuring chamber 42, a photocell 48 is arranged.

The light of the light source 47 radiates through the measuring chamber 42 and falls through a

Tubus 49 on the photocell 48. By using the tube 49, the incident on the photocell 48 scattering and ambient light is minimized. In the

Embodiment, the tube 49 has a diameter of about 2.5 mm and a length of about 5 mm.

The positions of light source 47 and photocell 48 with tube 49 can also be reversed. The light source 47 and the photocell 48 are arranged such that they are preferably connectable to each other substantially along the direction Mp straight. This means that the light rays, which in the following meet the photocell 48, propagate through the measuring chamber 42 substantially along the direction Mp. In this case, the direction Mp corresponds in particular to the longitudinal extent of the measuring chamber 42. As a result, the distance of the light through the sample mixture 4 located in the measuring chamber 42 is maximum, whereby the extinction effect of the sample mixture 4 maximum and other edge effects are minimal. Depending on the strength of the extinction and / or scattering of the light rays through the medium located in the measuring chamber 42, a more or less large light intensity impinges on the photocell 48, as a result of which its electrical properties are changed measurably. This measurement and the evaluation are carried out by the evaluation electronics 50 (see FIG. 1). In this embodiment, the measuring chamber 42 is cylindrical and has a diameter D ^ of about 7.5 mm to about 12 mm and a longitudinal extent H ^ along a direction Mp between the inlet portion 44a and the outlet portion 45a of about 35 mm. In this case, the measuring chamber 42, and the lines 44 and 45 are made by drilling monolithically from a transparent cylindrical polymer block having a diameter D _z of about 40 mm and a length H _z of about 50 mm to about 55 mm. Further, the sample mixture inlet 41 are formed as a 1/4 ZoII thread UNF G28 or thread 10-32 UNF and the outflow 43 as a 3/8 ZoII thread monolithic in the measuring cell 40.

As shown in Fig. 4, the measuring chamber 42 may alternatively be formed in a cuboid in the measuring cell 40 and an edge length D ^ of about 7.5 mm to about 12 mm and a longitudinal extent H ^ along a direction Mp between the inlet portion 44a and the outlet portion 45a of about 35 mm. In this case, the measuring chamber 42, and the lines 44 and 45 are made by eroding or machining monolithic from a transparent block-shaped polymer block with a short edge length H ₂ of about 30 mm to about 35 mm and a length of about 50 mm. Further, the measuring cell 40 includes a port for the suction device 62 (not shown in Fig. 4) to vent the measuring chamber 42 for starting up the titration device 1 by means of the suction device.

The sample mixture inlet 41 is formed as a 1/4 ZoII thread UNF G28 or thread 10-32 UNF and the outflow 43 and the terminal 43b for the suction device 62 are formed as a 3/8 ZoII threaded monolithic in the measuring cell 40.

It is understood that the light source 47 can be arranged or secured in various ways in the region of the end face 45b of the measuring chamber 42. As shown in FIG. 4, the light source 47 can be accommodated in a recess or continuous opening or bore in the area of the end face 45b. In the event that the recess is not continuous, that radiates from the light source 47th If the light source 47 is arranged in a continuous opening of the end face 45b, the light source 47 can at least partially protrude into the measuring chamber 42 and come into contact with the sample water.

As shown in FIG. 3, the light source 47 may be arranged in a light source receptacle 47a. The light source receptacle 47a is preferably provided in the embodiment shown with a 1/2-ZoII thread, so that the light source receptacle 47a can be screwed into the end face 45b. Advantageously, the light source 47 is easily interchangeable in this embodiment.

FIG. 5 shows a preferred embodiment of the light source receptacle 47a. The light source receptacle 47a in this embodiment includes a light guide 47b. which preferably consists of glass. The light guide is preferably cylindrical or frusto-conical. In the preferred embodiment shown, a cylindrical glass rod 47b is attached as a preferred light guide 47b having a diameter of about 5 mm and a length of about 23 mm in a continuous opening of the light source receptacle 47a, in particular by gluing. One end of the glass rod 47b protrudes into the measuring chamber 42 by about 3 mm. The light source 47 is attached to the opposite end of the glass rod 47b. The attachment can preferably be done by means of a piece of tubing or shrink tubing. Alternatively or additionally, the light source 47 may be glued to the glass rod 47b. The light emitted from the light source 47 is irradiated by the glass rod 47b into the measuring chamber. Advantageously, the glass rod is particularly chemically inert and resistant to staining and discoloration. Further advantageously, the penetration of the light guide 47b prevents gas bubbles which accumulate on the end face 45b from influencing the light beam.

It is understood that a light guide also in one embodiment of the 4 can be arranged or attached directly to the end face 45b of the measuring chamber 42, so that the features and advantages described above also apply to this embodiment.

INVESTIGATIONS

By way of example, the function of the titration device 1 is shown, namely on the basis of the determination of the water hardness of the sample water 2 to a pre-definable or predetermined limit.

The water to be examined is fed continuously and without pressure from the tapping point 12 of a pipeline to the sample receptacle 10. In the case of a completely filled sample receiving container 10, the excess sample water 2 flows through the overflow 16 in the sequence 60. Due to gravity sample water 2 flows through the sample water outlet 14 from the sample receiving container 10 and further in the sample water pipe 18 down into the mixer 30. Die Flow rate and thus the Probewasserflußrate dV / dt are predetermined by the choice of the sample water pipe inner diameter.

The indicator container 20 contains the liquid indicator 3, which has a green color in the usable state. By adding Ca ^ ⁺ or Mg2 ⁺ ions, for example by the salts contained in hard tap water, the indicator 3 turns red. By means of the suitable composition of the indicator solution or a suitable mixing ratio of sample water to indicator solution, the water hardness can be predefined or predetermined in particular in a range of 0.1 ° to 20 ° dH (German hardness) at which discoloration of the indicator 3 takes place, ie where the transfer point lies. The indicator 3 flows by gravity from the indicator outlet 24 of the Indikatorauslaßvorrichtung 22 and from there through the indicator line 28 down into the mixer 30. The flow rate and thus the Indikatorflußrate dV / dt are predetermined by the choice of the indicator line internal diameter.

In the mixer 30, the sample water 2 and the indicator 3 are mixed in a predetermined by the choice of the appropriate line diameter or predetermined ratio. In a preferred embodiment, the mixing ratio is 1 part indicator 3 to 500 parts of sample water 2. The preferred embodiment shown in FIG. 2 prevents the indicator 3 from being pressed back against the indicator line 28 against gravity.

A sample mixture 4, consisting of sample water 2 and indicator 3, passes through the test mixture outlet 34 in a trained as a reaction coil 38 sample mixing line 37. In the about 0.5 m long reaction coil 38 is formed by the spiral flow path turbulence, so that the sample mixture 4 sufficiently well is mixed. As a result, an accumulation of Ca ^ ⁺ - and Mg2 ⁺ ions to the contained in the indicator 3 ethylenediaminetetraacetic acid (EDTA) possible, whereby the indicator dye in the case of an excess of EDTA changes its color from not from green to red. Thus, it is identifiable by the color of the indicator 3, if the Ca ^ ⁺ - and Mg2 ⁺ ion concentration exceeds a predeterminable or predetermined threshold.

Thereafter, the sample mixture 4 flows through the sample mixture inlet 41 into the measuring chamber 42 of the measuring cell 40. There, the sample mixture 4 flows along the direction Mp from bottom to top along the longitudinal extent of the measuring chamber 42 through the latter to the outflow 43 and then into the outlet 60 both the flow direction of the sample mixture 4 and the longitudinal extent of the measuring chamber 42 along the direction Mp and Mp forms an angle of about 45 ° with the perpendicular Z, any gas bubbles occurring, for example, due to the heating and outgassing of the sample mixture, collected at the top of the measuring chamber 42, from where they rise in the direction of the outlet 43. Thus, a far-reaching Ensures freedom from bubbles in the measuring chamber 42.

On a front side of the measuring chamber 42 is a light source 47, which provides a red light. This is suitably a red light emitting diode (LED). Since the indicator has a color change from green to red, it is also preferable to use a light source emitting green light. On the opposite end face of the measuring chamber 42 is a photocell 48, which registers the light emitted by the red light source 47 and transmitted through the measuring chamber 42. Depending on the color of the sample mixture 4, red or green, there is a more or less strong extinction of the red light of the light source 47. The photocell 48 registered accordingly a more or less large incident light intensity, whereby the measurable between two contacts of the photocell 48 voltage or the current generated by the photocell 48 is correspondingly more or less large. Alternatively, instead of the red or green light source 47, a white light source can be used and a red or green color filter can be arranged in the beam path between the light source 47 and the photocell 48. In particular, the photocell 48 may have a color filter.

Depending on the indicator used 3, other color changes can occur (see also the example compilation in Table 3), in which case the color of the light source 47 can be selected appropriately appropriate, so that the registered difference in the light intensity in a color change is maximum.

Table 3: Possible exemplary color changes when using different indicators 3 and the light intensity registered thereby.

In particular, the measurable voltage or current difference becomes maximum when the light source 47 emits a colored light which substantially corresponds to the color or the complementary color of the liquid indicator 3. This measurable voltage or the measurable current is detected by the transmitter 50 and evaluated accordingly. The transmitter 50 comprises a display means which displays a function of the measurable at the photocell voltage and the measurable current, and thus from the sample mixture color, whether a predeterminable or predetermined threshold value of the Ca ^ ⁺ - and / or Mg2 ⁺ -lonen- concentration is exceeded.

During the first commissioning of the titration device 1, all lines must be vented, as air bubbles in the lines to hinder fluid flow to lead. Therefore, at the outlet 43 a suction device can be connected, such as a suction pump or a suction piston.

LIST OF REFERENCE NUMBERS

1 titration device

2 sample water

3 indicator

4 trial mix

10 sample receptacles

12 tap

14 sample water outlet

16 overflow

18 sample water pipe

19 sample water deficiency detection device

20 indicator containers

22 indicator outlet device

24 indicator outlet

26 indicator deficiency detection device

28 Indicator line

29 adapter piece

30 mixers

31 sample water inlet

32 indicator inlet

33 mixer pipe

34 sample mixture outlet

35 inlet

36 admixing line

37 sample mixture line 38 reaction coil

40 measuring cell

41 sample mix inlet

42 measuring chamber

43 outflow

43b connection for the suction device 62

44 line

44a inlet area

44b front side

45 line

45a outlet area

45b front side

47 light source

47a light source recording

47b light guide

48 photocell

49 tube of the photocell

50 transmitter

60 process

62 suction device

Mj extension direction of the indicator line

Mp extension direction of the measuring chamber

M _w direction of extension of the mixer line

Z vertical direction

Claims

claims

1. Apparatus (1) for continuous titration, in particular for determining the water hardness, of a sample water (2), comprising:

- A sample receptacle (10) for receiving the sample water (2), comprising - a sample water outlet (14);

- An indicator container (20) for receiving a liquid indicator (3), comprising

- an indicator outlet (24);

a mixer (30) comprising - a sample water inlet (31) passing through a sample water line

(18) is connected to the sample water outlet (14) of the sample receptacle (10);

an indicator inlet (32) connected by an indicator line (28) to the indicator outlet (24) of the indicator container (20) and

- a sample mixing outlet (34), wherein the sample water inlet (31), the indicator inlet (32) and the sample mixture outlet (34) are hydraulically connected to each other;

- A measuring cell (40), comprising - a sample mixture inlet (41) passing through a sample mixing line

(37) is connected to the sample mixture outlet (34) of the mixer (30),

a light source (47), a photocell (48),

- A measuring chamber (42), further comprising - an inlet region (44 a) and

- An outlet region (45a), wherein the inlet region (44a) and the outlet region (45a) are arranged in the measuring chamber (42), that the photometric measuring range between the light source (47) and the photocell (48) is free of bubbles.

2. Device according to claim 1, wherein the measuring chamber (42) is arranged extending substantially along a direction Mp extending in the measuring cell and the direction Mp and the perpendicular direction Z include an angle ß greater than 0 degrees and less than 90 degrees.

3. Apparatus according to claim 1 or 2, wherein the sample mixture line (37) is formed at least partially as a reaction coil (38).

4. Device according to one of the preceding claims, wherein the measuring chamber (42) is cylindrical, so that the cylinder axis defines the direction Mp.

5. Device according to one of the preceding claims, wherein the rectilinear connection of the light source (47) with the photocell (48) coincides substantially with the direction Mp.

6. Device according to one of the preceding claims, wherein in the beam path between the light source (47) and the photocell (48) at least one color filter is arranged.

7. Device according to one of claims 1 to 5, wherein the light source (47) emits colored light.

8. Device according to one of the preceding claims, wherein the light source (47) is a light emitting diode.

9. Device according to one of the preceding claims, wherein the radius of

Indicator line (28) is smaller than the radius of the sample water line (18), so that the ratio of indicator flow rate in the indicator line (28) to

Sample water flow rate in the sample water line (18) is less than 1:10.

10. Device according to one of the preceding claims, wherein the sample water inlet (31) and the Probegemischauslaß (34) of the mixer (30) are connected to one another substantially rectilinearly along a direction M _w through a mixer line (33).

The apparatus of claim 10, wherein said mixer conduit (33) has an inlet (35), said inlet (35) and said indicator inlet (32) being connected substantially rectilinearly along a direction Mj by an admixing conduit (36).

12. The apparatus of claim 11, wherein the direction M _w and the direction Mj include an angle α greater than 0 degrees and less than 90 degrees.

13. Device according to one of claims 11 or 12, wherein the sum of the line lengths of the admixing line (36) and the indicator line (28) is smaller than the capillary rise in these lines.

14. Device according to one of the preceding claims, wherein the sample receptacle (10) or the sample water line (18) have a sample water defect detection device (19).

15. Device according to one of the preceding claims, wherein the indicator container (20) or the indicator line (28) have an indicator lack recognition device (26).

16. Device according to one of the preceding claims, wherein the indicator container (20) has a Indikatorauslaßvorrichtung (22) to keep the applied pressure at the Indikatorauslaß (24) regardless of the level of the indicator (3) constant.

17. Device according to one of the preceding claims, wherein in the beam path between the light source (47) and the photocell (48) a light guide (47 b) is arranged, which projects into the measuring chamber (42).