DE8603519U1 - Device for measuring the level of an electrically conductive liquid in a container - Google Patents

Description

KRAFTWERK UNION AKTIENGESELLSCHAFT Our reference Mülheim a. d. Ruhr VPA M G 6 0 0 7 OE

Device for measuring the level of an electrically conductive liquid in a container

The present invention relates to a device for measuring the level of an electrically conductive liquid in a container according to the preamble of claim 1- It is known in various embodiments, to arrange electrical contacts at different heights in containers for electrically conductive liquids and with the aid of the electrically conductive connection established between them by the liquid Contacts to measure the ride height.

The object of the present invention is a particularly simply constructed level measuring device of this type, this device should be particularly suitable for retrofitting containers with simple means. Particularly the device should be suitable for small, relatively flat containers, for example for corrosion -Test vessels.

To solve this problem, a device according to claim 1 is proposed. Advantageous configurations are described in the subclaims.

The proposed device, which will be explained in more detail with reference to the drawing, can be made very compact and therefore largely miniaturize. It is particularly suitable for containers with heights of a few Centimeters, but is not limited to such use cases. The electrically conductive rods, preferably Stainless steel rods are inexpensive in any size

Khf 2 Fl / 24.01.1986

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and thicknesses are available and only need to be shortened to the desired length in the manufacture of the measuring insert. According to claim 6, a measuring insert according to the invention can therefore initially be equipped with rods of the same length, which the user can shorten with the simplest means according to his particular needs. As can be seen from the drawing, an inventive insert can be designed so that he or with commercially available Mehrspolsteckern or Mehrpolbuchsen in a simple manner with its power _s of the transmitter can be connected,

An embodiment of the invention is shown in the drawing, namely show

1 shows a schematic longitudinal section through the center of a measuring insert according to the invention,

Fig. 2 is a view from below of the measuring insert,

3 shows a perspective view of an associated power supply and evaluation unit and

4 shows a principle circuit diagram for the signal evaluation.

Fig. 1 shows the measuring insert 1 according to the invention in longitudinal section. The drawing, although not to scale, gives an approximate impression of the preferred one Size of the sensors. Fig. 2 shows a view of the measuring transducer 1 from below. The measuring attachment 1 has 4 Outer bars 3a, 3b, 3c, 3d of different lengths, which are arranged concentrically around a central bar 2 are, the central rod 2 about the length of the longest

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Has outer rod 3a. All bars are by means of one suitable sealing and insulating material 4, preferably polytetrafluoroethylene electrically isolated from one another in one Bracket 5 attached. This bracket has a thread 6, with which the entire measuring insert in the ceiling of a Container can be screwed in, possibly with the interposition of a seal, not shown. The bars 2, 3a, 3b, 3c, 3d lead through the holder 5 and directly form the pins of a multipole connector on the opposite side 8, which can be connected to a commercially available socket. With suitable dimensioning, • in particular so-called cubic connectors, as they are, for. B. used in stereo systems to connect the measuring insert use. A metallic shield 7, which is attached to the bracket 5, completes thereby the connector formed in this way. The z. B. Commercially available multi-pole cables used in stereo systems with cubic plugs have a shield in addition to the electrical inner wires, which also when applied to the present invention, it is advantageous because external interference can be reduced. The measuring insert 1 described can preferably be screwed into container ceilings, the rods .2, 3a, 3b, 3c, 3d protrude approximately parallel to one another perpendicularly into the interior of the container, where depending on the level of the liquid one or more of the outer rods 3a, 3b, 3c, 3d are electrically connected to the central rod 2. Naturally can by suitable bending, i. H. Angling of the rods 2, 3a, 3b, 3c, 3d, the measuring insert also in the upper one Area of a container wall can be used in almost any installation position.

In Fig. 3 is a power supply and evaluation unit schematically shown for measuring inserts according to the invention.

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In general, a power supply and evaluation unit can be used for several measuring inserts, whereby a selector switch enables the measuring point to be switched. The present embodiment is designed for 5 measuring inserts, which are commercially available multi-core Lines with commercially available plugs can be connected to the sockets 11a, 11b, 11c, 11d, 11e. A selector switch 12 enables the desired measuring point to be selected. The display is preferably made via light-emitting diodes 13a, 13b, 13c, 13d, which light up when the liquid wets the associated contact. A switch 14 is used to turn on and off a Power supply.

In Fig. 4 is an example of a particularly suitable and yet simple power supply and evaluation circuit shown. For the sake of clarity, the bars 2, 3a, 3b, 3c, 3d are shown next to one another in this figure, likewise the multipole socket 8 ', the cores of the associated multi-core line 17 and the socket 11a. A current. Supply 15, which consists of a Netztransfo ^ mator with power switch 14 or a suitable battery, supplies the necessary for the operation of the measuring insert Tension. This voltage, for example about 18 V, is on the one hand at the mean

t bar 2 on and on the other hand, each parallel to the outer

bars 3a, 3b, 3c, 3d. In the supply line to each outer rod 3a. 3b, 3c, 3d are each a light emitting diode 13a, 13b, 13c, 13d in series with a so-called PTC thermistor, too Called PTC, arranged. Such PTC thermistors conduct electricity very well when they are cold, but they also heat up Current flow and thereby significantly increase their resistance. A PTC thermistor is preferred in the present circuit

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with a very progressive characteristic, which increases its resistance in a very short time when there is a large current flow. In this way, the PTC thermistors 16a, 16b, 16c, I6d protect the light-emitting diodes connected in series 13a, 13b, 13c, 13d, even if a relatively high supply voltage is used. As a result, the proposed circuit is used for signal evaluation of the measuring insert in large areas independent of the conductivity of the liquid, its level is measured should be suitable. This is particularly advantageous in the case of the corrosion test vessels mentioned, since there are liquids of different conductivity and even with conductivity that changes as a function of time can be used. Accordingly, the inventive Measuring insert also for liquids is very low Conductivity can be used, e.g. B. for fully demineralized water. Even this will not be electronic Amplifier is required, so that the device is very simple, robust and less susceptible to interference and can be used as an industrial measuring device lets use. It is of course possible to use more than 5 rods in one measuring insert, provided that more measuring points are required. In addition, there is the option of using electrically conductive vessels not through one of the rods, but through the container wall, and all rods each have specific fill levels assign. It is also possible to use several measuring inserts in one container, but not every one of them The measuring insert must have its own power supply, which means that the number of measuring points can also be increased.

Protection claims

characters

Claims (8)

- 6 - VPA B6 G 6 O O 7 OE Protection claims 1 . Device for measuring the level of an electrically conductive liquid in a container, wherein the device has a plurality of electrical contacts arranged at different heights in the container, which through the liquids can be electrically connected to one another or to a reference contact, characterized in that, that the electrical contacts as rods (2, 3a, 3b, 3c, 3d) made of electrically conductive material are formed, which are fastened in a common holder (5) insulated from one another, rods (2, 3a, 3b, 3c, 3d) and holder (5) together form an exchangeable measuring insert (1). 15th 2. Device according to claim 1, characterized in that that the holder (5) can be used in a sealing manner in a container ceiling and the rods are tight (4) are guided through the bracket (5). 20th 3. Apparatus according to claim 1 or 2, characterized in that the holder (5) on its Outside a multipole socket or a multipole plug (8).
25th 4. Apparatus according to claim 1, 2 or 3, characterized in that the rods (2,3a, 3b, 3c, 3d) consist of a corrosion-resistant material, preferably stainless steel. 5. Device according to one of the preceding claims, characterized in that the Rods (2, 3a, 3b, 3c, 3d) in the holder (5) by means of a temperature-resistant, chemically resistant insulating and sealing material (4), preferably polytetrafluoroethylene , t · · · ι »· t * t ι« t II »■ ι ι Ι ι ■ ■ ι>'' - 7 - VPA 86 G 6007 DE are attached. 6. Device according to one of the preceding claims, characterized in that the rods (2, 3a, 3b, 3c, 3d) all initially have approximately the same maximum length. 7. Device according to one of the preceding claims, characterized in that the measuring insert (1) has five rods (2, 3a, 3b, 3c, 3d); of which 4 outer bars (3a, 3b, 3c, 3d) of different lengths are arranged concentrically around a central bar (2) are, wherein the central rod (2) has approximately the length of the longest outer rod (3a). 8. Apparatus according to claim 7, characterized in that that the rods (2, 3a, 3b, 3c, 3d) pass through a seal (4) and on the opposite side directly form a multipole connector (8), preferably a so-called cubic connector, which is marked with ζ F. common sockets for stereo systems.