DE2037497C3 - Excess chlorine meter - Google Patents

Description

The invention relates to a chlorine excess measuring device according to the preamble of claim 1.

Measuring devices of this type are from DE-PS 669628 and U.S. Patent 2,370,871.

In the measuring arrangement known from US Pat. No. 2,370,871 the two electrodes are separated from each other by a permeable partition a common electrode vessel, the cathode with chlorinated water, the anode is surrounded by non-chlorinated water, acid or a salt solution, including in addition to the partition Separate fluid connections and additional line arrangements are necessary in the electrode vessel are. From DE-PS 669628 it can be seen that when anode and cathode made of the same material are used, the two electrodes are separated at least through the said partition for proper operation of an amperometric Cell is assumed.

The invention is based on the object of a Excess chlorine meter accurately measuring long periods of time regardless of any excess chlorine present to create according to the preamble of the main claim, which with a single inflow and a drain connection for an amperometric cell does not have a permeable partition wall, wherein only chlorinated water flows through the cell.

The task at hand is achieved with the characterizing features of the main claim.

When monitoring and continuously measuring the excess chlorine in water with fluctuating The temperature in the inlet of the plastic body is influenced by the flowing water temperature-dependent compensation resistor

ordered, the one with one pole of the voltage source

and is conductively connected to the measuring electrode.

On the outlet of the plastic body can a

adjustable flow meter, which then forms a structural unit with the cell, which is called Gan-ο zes inserted or replaced in the water cycle can be.

The invention is for an embodiment in

the drawing shown and explained in more detail. It shows 1 shows, in simplified form, a chlorine excess measuring device connected to a voltage source,

Q: g. 2 shows a voltage-current characteristic curve of the cell according to FIG. 1.

The chlorine excess meter for monitoring the chlorinated water of swimming pools, from Drinking water reservoirs, of cooling towers in connection with power plants, air conditioning systems or the like, using chlorine as a disinfectant or as an algazide to prevent the formation of microorganisms is added, a cell 10, a flow meter 11 with valve 12, an ammeter 14 and a thermistor with large negative temperature coefficient of resistance as a compensation resistor 13 on. The Zdte 10 consists of a transparent, insensitive to chlorinated water Plastic body with an inlet 15 in which the thermistor 13 protrudes so that it is in direct contact to the flowing water. In the hollow middle part of the plastic body is a support part

J5 of the measuring electrode 17 is provided, which at a distance of the reference electrode 18 is concentrically surrounded. Between the annular reference electrode 18 and the likewise ring-shaped or disk-shaped measuring electrode 17 is an annular flow opening 16, which faces the two ring-shaped active surfaces of the electrodes made of copper so that the water in the cell is in contact with the two electrodes. The ring-shaped The flow opening is with a variable area flow meter placed on top of the plastic body connected to conical measuring tube 19 and float 20 as well as valve 12 and outlet 21. The valve 12 can be used to control the amount of water flowing through the cell 10 in the parallel path.

vt and are indicated by the float position in the measuring tube. The change in the flow rate can be, for example, up to V ₄ l / min, the measurement of the excess chlorine remaining stable.

r, The measuring electrode 17 is directly connected to the negative, the reference electrode 18 via the thermistor 13 connected to the positive pole of a battery 22. An ammeter 14 is parallel to the thermistor 13 switched so that with rising water temperatures

the resistance of the thermistor decreases accordingly and vice versa.

InFig. 2 is the respective relationship between the voltage applied to the electrodes in volts and the one supplied by this to the ammeter

h <-, current shown in microamps, namely
Curve A for unchlorinated water,
Curve B for water with free chlorine and
Curve C for water with free and bound

Chlorine,

Curve B shows that if there is free excess chlorine in the water, the change in voltage at the cell with increasing negative voltage due to the reduction in chlorine at the measuring electrode ultimately results in a cathode current which remains at a limit value with further increase in negative voltage within a saturation zone. The limit current is due to the mass transport of chlorine from the solution to the measuring electrode surface and is proportional to the main chlorine concentration in the water. Only with a further increase in the negative voltage beyond the saturation zone does a reduction in the electrolyte cause the current to rise above the limit value.

The transition from the increasing current to the constant limit current at 1 [ppm] free chlorine in the water takes place at the optimal voltage of, for example - 0.15 volts, at which curve A no current flows in unchlorinated water.

The higher chlorine concentration (2, 3 etc. [ppm] free chlorine) with unchanged optimal The limit currents that result in voltage are proportional to the respective concentrations.

So if you keep the voltage within the saturation zone at or around the optimal value the display of the ammeter 14 is a measure of the Content of free excess chlorine of the cell flowing through chlorinated water, the display is within a range of the pH values of the water between 5.5 and 9.0 exactly.

If there is also bound chlorine in water, which, according to curve C, only has an influence on the current when the voltage is noticeably more negative than the optimal voltage, this influence can nevertheless enable an exact measurement of the decisive free chlorine excess alone by maintaining this voltage, since In this voltage range the measuring device is insensitive to combined chlorine.

In the cell with copper electrodes, the sensitivity of the measuring electrode remains for several months obtained without the addition of buffer reagents or the like. Because the output size of the cell is the chlorine content is proportional, it can be used for process control with automatic chlorine metering in swimming pools etc. can be used to achieve a desired excess chlorine concentration to be adhered to at all times.

1 sheet of drawings

Claims (3)

Patent claims: 1. Chlorine excess meter for continuous Measuring the level of free excess chlorine in chlorinated water using one amperometric cell through which the chlorinated water flows, with two copper cells, Electrodes connected to an external voltage source, characterized in that that the annular reference electrode (18) in the inner wall of the central part of one of the Chlorinated water flowed through the plastic body and the ring-shaped or disc-shaped measuring electrode (17) in a support part arranged concentrically in the middle part opposite the reference electrode is arranged so that the inner or outer circumference of the electrodes is uncovered directly in contact with the chlorinated water flowing in the annular flow opening (16) stand. 2. Measuring device according to claim 1, characterized in that that on the outlet of the plastic body an adjustable flow meter (11) is put on. 3. Measuring device according to claim 1, characterized in that in the inlet (15) of the plastic body a temperature-dependent compensation resistance influenced by the flowing water (13) is arranged with one pole (+) of the voltage source (22) and with the measuring electrode (17) is conductively connected.