DE2444199A1 - DEVICE FOR REGULATING THE CONCENTRATION OF CHEMICAL SUBSTANCES IN A LIQUID - Google Patents

Description

PATENTANWÄLTE DRes. KADOR & KLUNKER

8 Munich 22. KnoebeJstrasse 36

K 10 988 3 / tr

Robert Peter Thomson and John Edward Stiff St. Savior, Jersey, Channel Islands

Device for controlling the concentration of chemical substances in a liquid

The invention relates to a device for controlling and regulating the concentration of chemical substances in a liquid.

There are many cases when it is desirable to concentrate a chemical substance to control and regulate in a liquid. One of these cases is the regulation of the pH value or the chlorine content of swimming pools. Similar

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Problems arise with various processes and equipment, e.g. in the field of water treatment.

A general method of performing such a control is to periodically take samples of the To take liquid, to add a reagent to these samples which causes a color, and depending on the color obtained, adding more chemical substance to the concentration increase in the liquid, or make no further addition.

According to the invention, a device for Control of the concentration of chemical substances in a liquid created a sample chamber with transparent walls, means for introducing a sample of the liquid into the chamber, means to keep the amount of liquid in the chamber constant, means for periodic introduction an amount of indicator solution into the chamber and mixing it with that to be tested Liquid in the chamber, a stabilized light source on one side of the chamber, a photoelectric Detector on the opposite side of the chamber, comparison means to compare one Value corresponding to the light displayed by the detector with a preset value, and Control devices connected to the output of the comparator ».

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Means can be provided to monitor the output of the photocell for a Provide a visible display showing the measured concentration.

In such a device, a sample of the liquid to be examined is generally with a precisely measured amount of a reagent mixed in the sample chamber itself. Mixing can caused by mechanical movement, either of the viewing chamber as a whole, or by rotating a chemically inert magnet on the bottom of the sample chamber. The preferred one The method, however, is to bubble air through the liquid. This has the Advantage that iron present in the sample to be examined is eliminated. The sample chamber therefore preferably consists of a vessel with glass walls, a liquid inlet and a Liquid overflow and an air inlet opening below the overflow and an indicator solution inlet opening has above the overflow. The mixing device preferably consists of one Storage vessel or a supply for compressed air that connects to the air inlet opening of the glass vessel are connected.

When transmitting light through the sample chamber using a suitable liquid and Indicator solution is in the photoelectric detector (preferably a photo element) generates a signal,

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which depends on the optical change, e.g. a color change, caused by the reaction between the liquid to be examined and the reagent is generated. For example, during the examination the chlorine content of swimming pools, the reagent used should be o-tolidine, which has a yellow color gives. The deeper the color, the higher the chlorine content. When the chlorine level is lower is as a desired value, the response of the photoelectric detector can be so designed be that it is high enough to provide a control signal to a chlorine injection pump or other chlorinator to provide an appropriate amount of Bring chlorine into the swimming pool.

The device is generally arranged to operate cyclically, although the time cycles can be very different. A typical cycle time for swimming pools is 15 minutes, i.e. 15 minutes each a sample is taken, examined, and corrective action taken if necessary. to For this purpose, the device may contain switching devices which are designed so that in predetermined At intervals in the indicator solution chamber is introduced, this is mixed, is exposed to the light source, the comparison device in Is put into operation and depending on the output signal of the comparison device, the actuating devices operate. Preferably, this switching device comprises a plurality of cam-operated switches, which on a rotatable shaft are attached, the end of the

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Shaft carries a roller that is connected to a peristaltic pump tube for the indicator liquid stands.

The cam-operated switches can usually be microswitches or, alternatively, the cams can be the path from a light source to a high power resistance cell (Photoconductor cell) or not. Such a system avoids electrical "peaks", which can arise when using microswitches and the operation of the other solid state circuits adversely affect. Reed relays can also used to avoid this difficulty.

The light source should be carefully selected, with the desired spectral distribution of the light, their self-changeability and their reliability must be observed. Preferably the light source comprises a filament lamp and an associated voltage-stabilized supply circuit that is designed in this way is that at least a voltage of 10% below the normal working voltage of the lamp is fed. The stabilized supply circuit is preferably using Zener diodes tension s s tabiIi si ed.

Other light sources that can be used are fluorescent tubes and solid state light sources, like GaAs devices. If desired, a feedback stabilized light source can be used, a second photoelectric detector on the

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Lamp intensity responds and the supply voltage adjusts to keep this intensity constant. However, such changes can be tolerated, when the value obtained from the light transmitted through the chamber is not measured in absolute terms but relative to the light value that occurs when the liquid passes through the chamber does not contain any indicator solution.

In such a system, in the examination cycle, the cell is first filled with liquid but without an indicator solution illuminated, a value corresponding to the transmitted light, saved, indicator added, the liquid in the chamber mixed, the new value of the transmitted light measured and the difference the two values are compared against the preset value. False readings due to soiling, Lamp aging, aging of the photoelectric device and haze are minimized in this way limited.

In order to emphasize the particular color change in question, it is convenient to place the light on the light to filter one or more filters between the photoelectric detector and the chamber, wherein the color of the filter or the filter corresponds to the color of the mixture of the liquid to be examined and the indicator solution is related. E.g. should when examining the chlorine content using of o-tolidine as an indicator, which is a yellow solution results, a blue filter should preferably be used.

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Blue and green filters should be used when determining pH and phenol red as an indicator is used.

The light source and the photoelectric detector can, if desired, be spaced from the chamber be arranged and the 'taking place on opposite sides of the chamber light supply and light removal can with the help of light pipes or optical fiber devices be performed. Such systems have the advantage that the electrical parts and the parts for treating the liquid of the device are separate and that effects of temperature change, caused, for example, by changing the temperature of the liquid, on the electrical components can be reduced to a minimum.

The design of the sample chamber is sometimes essential. Preferably the chamber is cylindrical and made of glass made although acrylic resin materials are also used can be. The inlet for the liquid to be examined should be at or near the bottom of the Be chamber. The liquid level in the chamber is preferably controlled by a fixed overflow set. When used, the liquid to be examined is introduced into the chamber and by means of the Overflow discharged. When the flow stops, there is always the same amount of fluid left in the chamber. · This way of working has the advantage that the liquid to be examined is added to it used to clean and rinse the chamber with each cycle. Alternatively, the system can be continuous

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be, namely either the continuous flow for examining the sample can be interrupted in a predetermined time or the indicator solution can be introduced continuously during a short test period. The indicator solution is preferably introduced into the viewing chamber through an inlet located above the overflow and radially spaced therefrom. In order to ensure vigorous mixing, as described above, preferably an air inlet is provided below the overflow, through which air is blown in as described above. The liquid in the chamber and the indicator solution may be mixed by the chamber _# by the bubbling of the air during the cycle.

The supply of the liquid from the liquid to be examined can simply by gravity done or by pumping. A simple controllable valve, e.g. a solenoid valve, can be installed in the supply line for the liquid to regulate the supply. The geometry of the chamber's should be chosen so that there is an even flow without splashing. The capacity of the overflow should be large in order to minimize the risk of flooding when the inflow of liquid is high to restrict and it may be advantageous to provide a "chimney" as an emergency container, or a small one Flow limiter, which is located on the inlet pipe, to control the flow rate so that it is ensured that no flooding of the

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244A199

- 9 sample chamber occurs.

The introduction of an exact amount of indicator solution into the sample chamber can be done in any suitable manner. As mentioned above, there is preferred system in which, around part of the circumference of a circle on the rotating timer shaft, (if a central squat / timer is used) to place a peristaltic pump tube and a pump roller attached to the shaft, to be provided. One end of the pump tube is connected to the supply to the sample chamber and the other with a reagent container. The supply and feed tubes are preferably small in diameter to keep the reagent stationary in these due to capillary effects. Between the pump tube and A suitable control valve is provided in the viewing chamber to ensure pumping and prevent backflow. A small plastic valve that works on the principle of a one-way valve works is suitable for it.

The reagent reservoir can preferably be filled easily and preferably has devices that indicate when the level of the container sinks too low. Conveniently, the container has the Shape of a vertical cylindrical tank with a float that floats on top of the liquid and if the mirror drops too far, actuated a microswitch to display a visible and / or audible display, that the reagent reservoir has to be refilled. Other display methods, such as

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Temperature or capacitance sensors can be used in analog Way to be used.

If desired, parts of the device can be doubled to control more than one parameter at the same time.

For example, the chlorine concentration and the pH value of a swimming pool independently by using suitable reagents and subsequently carried out Corrections, if necessary, can be regulated.

The invention is explained in more detail below with reference to the accompanying drawings.

Show it:

Figure 1 is a diagrammatic perspective view of part of the control device according to the invention when used in connection with a swimming pool,

Figure 2 is a schematic circuit diagram showing the shows electrical working parts of the device of the figure,

Figure 3 is a circuit diagram of the electronic board of Figures 2 and 4

FIG. 4 a regulation or control diagram.

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Figure 1 shows in particular a swimming pool 1 with an outlet via a solenoid valve 2 and a Flow limiter 3 with a viewing chamber 4 connected is. The viewing chamber 4 is made of glass and has a liquid inlet 5> Overflow 6 to automatically ensure a constant liquid level, a reagent supply opening 7 and an air inlet port 8. The parts 2 to 8, as well as others, are on a common carrier 40 assembled.

On opposite sides of the chamber 4 are lamp 11, a blue filter 44 and a photocell 12 arranged. The output of row 12 is connected to a printed circuit board 13. The plate 13 included an amplifier, which in turn came with a Comparator is connected, which compares the output signal of the amplifier with a predetermined reference value. The output signal of the comparator is sent via a relay an injection pump 15 fed to a suitable Reservoir, which contains the material to be introduced into the bath 1, is coupled. When the signal of the Photocell 12 'is suitably too large or too small, pump 15 is actuated, the material pumps via line 17 into the bath 1 to the examined Set the parameter to the desired value.

A small ventilation pump 18 is connected to the air inlet 8, the viewing cell 4. The ventilation causes Not only does it mix, it also keeps the build-up of calcium and iron as well as staining on one Minimum. The prevention of staining is important

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24A4199

especially important. In known chlorine control devices, this has hitherto been an insurmountable problem.

With reagent inlet 7 is a regulating valve 20 and a peristaltic pump tube 21. The supply end of the tube 21 is opened by gravity filled from a vertical cylindrical container 22. A float 23 swims in container 22 The upper end protrudes through an opening in the lid "of the container and carries a plastic collar 10. If the float drops when the container is low, collar 10 will contact the arm of a microswitch 24, which is attached to the lid of the container is. When the reagent level is low, the container can easily be filled with the aid of a side tube 25 which is arranged parallel to and connected to the main container pipe 22. So that the Reagent level is easy to see are the tubes and 25 preferably made of clear or translucent Made of plastics. The materials of the tubes 22 and 25 should of course be compared to that reagent used must be inert and resistant.

In order to move along the peristaltic pump tube 21, a roller 27 is arranged on an arm 28 which rotates on a shaft 29. Cams $ 0 , to which microswitches 31 are related, are also attached to the shaft. The shaft 29 is set in rotation by a motor 32. The operation of the motor 32 is controlled by a microswitch 41 which is operated by a nooke which is rotated by the main control motor 42 which operates once every 15 minutes

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- 13 rotates.

On the carrier 40 there is also a power pack 45 for the electronic equipment attached.

The circuit of the device of FIG. 1 is shown in FIG. This is practically of itself understandable. Various components in FIG. 2 have been given the same reference numerals as in FIG designated.

The circuit essentially consists of a power supply unit 45, in which a normal mains alternating current is converted into a stabilized supply voltage for a lamp 11 and a stabilized supply voltage for the amplifier, comparator and the signal evaluation or Gate control circuit shown in Figure 3 is converted and various control loops. Neon lights are provided at strategic points of the circuit and their indication when they burn is in figure 2 and is self-evident.

The timing of the device is controlled by a motor 42 controlled with one rotation every 15 min, the ζ v / ei Drives cams (A and B in the circuit diagram). Cam A drives another timer with one revolution per minute on and this timer performs the sampling, mixing and evaluation functions. Cam B of the 15 min timer regulates the hold time of the chlorine pump relay. Should the relay be operated (chlorine required) Cam B unlocks the relay after about 10 minutes and in this way before the next sample

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The cam B is adjustable, but it should be noted that it is much better to slowly release the chlorine into the water than to dose it briefly and strongly, and that it is better to discharge the Adjust the chlorine pump, rather than ^{shortening the "on M"} period and lengthening the holding time by changing cam B.

Once cam A of the 15 min timer initiates a feed to the 1 min timer motor, cam 5 of this second timer closes the associated switch and ensures that the motor completes one revolution and thereby performs all its functions. At the end of Sequence opens the switch of cam 5 and the The motor stops until the next feed from the 15 min timer takes place (see FIG. 4).

Should the container 22 become empty, the microswitch 24 on the top of the container will through Collar 10, which is attached to the float arm, which in turn is on the float 23 in the container is located, actuated. The switch then interrupts the supply to the transformer (see electrical Circuit, Figure 2) and causes the lighting of a warning light 48. The interruption of the supply to Transformer is preferred because if the regulator is left in operation without the addition of indicator solution the water sample would be colorless and the electronic equipment this as a condition

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would view without chlorine, and therefore the chlorine pump relay 47 would be actuated each time a sample was taken. This "failure monitoring condition ^11" can be prevented by means of a manual / auto switch 49 which connects the supply voltage directly to the chlorine pump socket, the other pole of this switch being used to supply voltage to an indicator light and in this way to indicate that this condition exists.

The supply voltage to the controller comes through the 3 ampere fuse, the reagent blank switch and the 1 ampere fuse to a transformer Tl. The The primary winding of this transformer is tapped for 115 and 240 VAC. All with alternating current powered units of the device (timer motor, solenoid, air pump, neon lights) permanently connected to the 240 V tap. If the converter is to be used with a 115 V network, the primary winding acts as an auto converter and 240 V are available for the 240 V tap to operate these units.

DTe secondary winding feeds 30 V to the electronic board namely at terminals 11A and 12B of the panel and 15 V at terminals 7B and 8B (see FIGS. 2 and 3).

The timer stop switch 31, which the supply voltage interrupts for the 15 min timer and puts a lamp into operation is to start up the device intended.

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One hour chorus 53 is directly over the pump feed socket and records the total number of hours the pump has been used.

The electronic sequence is described below with reference to FIGS.

The functions of the power supply are as follows:

30 VAC supplied by the transformer is rectified by means of a double rectifier D1 and by means of an electrolytic comparator C1 330, u F smoothed. This direct current supply is then regulated and by means of the two 12 V Zener diodes Z1 and Z2 and the 5 W, 250 ohm resistor, called the Zener load resistor works, tapped centrally. The DC power supply received for the board is 12 volts positive, 0 V when connecting the two Zener diodes and 12 V negative. The effect of the Zener diodes is there therein, the 12 V supply independent of voltage changes of the network and thus of the transformer to maintain. The 15 VAC supplied to the lamp circuit is generated by means of diodes D2-5 double rectified and by means of 1000, u F electrolytic capacitor 02 smoothed. "The DC voltage is stabilized by the Zener diode Z3 at 15 V, E2 and 220 ohm resistor acts as a Zener load resistor. This tension is related to the base of TR2 connected, which in turn via its emitter to the base of TR1, the power transistor, which the Lamp feeds, is connected.

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The gate direction works as follows:

With the viewing lamp switched off and the ELA pump relay coil not excited. is held in the blocked state via the TE4 transistor, a PNP transistor, through the positively charged base via E24 with the positive 12 V supply! The gate of the field effect transistor TR3 is over. D6 and E23 are held at negative voltage by the 12V negative rail, and that field effect transistor is turned off.

The TE5 and KPN transistor, which controls the pump relay coil RLA, is kept in the blocked state by the negative voltage applied to its base via E 26 from the 12 "V negative supply. The ΊΑ

Zener diode prevents this negative voltage from appearing at the drain electrode of TR 3 and both of them Steps effectively isolated.

When the viewing lamp is in operation via cam 3 is set, "the cut-off voltage between the two inputs to the operational amplifier C11 changed by the photo element, with one Voltage is obtained which is proportional to the light intensity falling on it. This light intensity changes according to the color of the liquid in the viewing chamber, which is between the light source and cell is located. VE1 and VE2 are preset resistors that are used for this stage to ensure a required range and changes in the output of the cells to compensate.

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The output signal of the integrated circuit IG 1 is connected to an input of IC2 and is further strengthened. The gain factor is kept low on all ICs to improve stability.

The output of IG2 becomes' via R16 with an input (Terminal 2) connected by IC3. The other entrance will Wired via R17 to the variable resistor VR4-. This regulates the amount of positive voltage fed to this input of IC 3 · Through Application of more positive voltage to IC3 via VR4 the point at which the IG gives an output is decreased and IGJ with the sample in the Viewing chamber related. It can be seen that as the color of the sample gets darker (more chlorine) less light falls on the cell and a lower voltage is applied to terminal 2 of IC3 from the output of IC2 will. When the chlorine level is the required, then VR4 is moved to turn the voltage on Change terminal 3 of the IC3 until there is an output signal is achieved, which ensures that this value is maintained.

At the time of sampling and measuring that chlorine is required, cam / switch 4 of the 1 min timer will cause the base of TRM- to go negative, making connections across terminals 10A and 14-A on the electronic board. The collector of TR4 goes positive via the EBC connections and effectively blocks diode D6. Therefore the negative voltage at the gate electrode of the field effect

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transistor TRp, which keeps this blocked, removed. The positive voltage from the terminal 6 of the IC 3 is applied to the gate electrode via R20, R21. As a result, this voltage is also applied to the source electrode of TR 3 in order to reach the drain electrode of TR 3 via the barrier layer. This voltage is higher than the reverse Zener breakdown voltage of TA- and therefore this positive voltage appears at the base of TR4- which conducts and the coil of RIA is energized. A pair of RLA1 contacts on this relay are used to hold the relay "on" via cam / switch B of 15 min timer 4-2. 1 min timer cam / switch 4 opens and and TR3, 4-, 5 return to the "off" state as discussed above.

RIA (Relay 4-7) stays energized until Nooke / Switch B this unlocked. This is the holding time until the next sample. If no output signal is off IC3 occurs (no chlorine required), TR3 is not switched on and consequently also not TR5 · The relay is therefore not excited.

An output signal can be sent from terminal 6 from IC3 to terminal 9B of the connector block after connecting the terminals 1B and 2B for the purpose of a written record be removed. The voltage range is about 1 V (clear water) up to 10 V. During the time at from which no samples are taken, this voltage rises to around 11 V. With more sensitive recording devices terminals 1B and 2B can be connected and the voltage now appears on terminal 9A via R12 and VR3.

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The timer / sampling sequence repeats itself automatically until the reagent level falls too low and the float 23 the microswitch 24- actuated.

As mentioned above, the device shown can be doubled to, for example, both the chlorine concentration how to analyze and regulate the pH. Such a unit could have two viewing chambers and comprise two reagent containers, doubling most of the other parts of the device however, can be avoided by a suitable circuit.

In a modification, a second 15 ^m in the main timer unit can additionally be used so that the unit is able to analyze continuously. The device described then doses a maximum of 14 minutes and the remaining minute is required for sampling. If two timers are used, set 7½ minutes apart, continuous dosing can take place, which is advantageous when the device is used in applications where no "circulatory system", such as swimming pools and sedimentation tanks, is provided .

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Claims (1)

- 21 claims 1.) Device for controlling the concentration of ^ - ^^ chemical substances in a liquid, thereby characterized in that they have a sample chamber with transparent walls, facilities for Introduction of a sample of the liquid in the chamber, means for keeping the amount of the Liquid in the chamber, means for introducing a quantity of indicator solution periodically into the chamber and for mixing it with the liquid to be examined in the chamber, a stabilized light source on one side of the chamber, a photoelectric detector on the opposite Side of the chamber, comparison means for comparing a value equal to that with the detector indicated light corresponds, with a preset value, and controls that with are connected to the output of the comparator. Device according to claim 1, characterized in that the chamber is a vessel with glass walls is an inlet for the liquid and an overflow for the liquid, an inlet opening for air, which is arranged below the overflow, and an inlet opening for the indicator solution has above the overflow. 509812/0856 3. Apparatus according to claim 2, characterized in that the mixing device is a Source of compressed air connected to the air inlet port of the vessel with glass walls, includes. 4-. Device according to one of Claims 1 to 3 »characterized characterized in that it comprises switching devices which are designed such that indicator solution is introduced into the chamber at predetermined intervals, this is mixed, this is illuminated with a light source, the comparison device is actuated and depending on the off. output signal of the comparison device, the actuating devices are put into operation. Device according to claim 4-, characterized in that the circuit device comprises a plurality of cam operated switches mounted on a rotatable shaft, and wherein the end of the shaft carries a roller with a peristaltic pump tube for the indicator liquid communicates. 6. Device according to one of claims 1 to 5i It is noted that the light source is a filament lamp and an associated one voltage-stabilized supply circuit that has at least a voltage of 10% below normal 509812/0856 - 23 working pairing of the lamp supplies, includes. 7. Device according to one of claims 1 to 6, characterized in that the value that the through corresponds to light displayed by the detector, derived from the difference in values when the light the chamber passes with only liquid present, and on the other hand the chamber passes with liquid and indicator solution are present. 8. Device according to one of claims 1 to 7> characterized in that the photoelectric detector is a photo element. 9- device according to claim 8, characterized in that between the photo element and one or more of the chamber according to the color of the examined mixture of liquid and indicator solution Filters are arranged. 10. Device according to one of claims 1 to 9, characterized in that a container for the indicator solution and devices for indicating that the level of the solution in the container is below a predetermined value has fallen, and devices to visually indicate this are provided. 509812/0856