JPS5922177B2 - pH measuring device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a pH measuring device.

Large-scale process pH measuring devices used in the chemical industry, petroleum refining, petrochemicals, etc. have already been realized. However, the use of these devices for pH measurement in wastewater from small factories is disadvantageous in various respects. An object of the present invention is to realize a simple measuring device suitable for use in measuring pH in waste liquid of such small factories. The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the apparatus of the present invention.

In the figure, AA is a pH measurement probe, BB is a recorder,
CC is a cable connecting the pH measurement probe AA and the recorder BB. The pH measurement probe AA includes a detection section DET having a measurement electrode, a reference electrode, and a temperature measuring resistor, a signal conversion section CON that converts the output of the detection section DET into a signal using an internal impedance conversion circuit, and a signal conversion section CON that converts the output of the detection section DET into a signal using an internal impedance conversion circuit. First, the detection section DET will be explained using FIG. 2.

In this detection part DET, 1 has a glass electrode film 1 at one end.
01, and a pin 102 as a contact is provided at the other end. Further, near the electrode film 101 of the measurement electrode 1, a ring-shaped sealing protrusion 103 made of an elastic material such as rubber is provided. Reference numeral 2 denotes a man's body container composed of a bottomed cutout cylinder 210 and a lid 220.

At the bottom of the upper part of the bottom male tube 210, there are through holes 211 to 213.
is formed, and a threaded portion 21 is formed at the bottom of the through hole 213.
4 is formed. Further, a through hole 215 is formed in the cylindrical portion of the bottomed cylinder 210. The lid 220 is
It has inner tube parts 221, 222 on its upper side, and on its lower side,
It has a tube portion 223 coaxially disposed with the inner tube portion 221 and threaded with a circumference. This lid 220 has a through hole 224 connecting each hole of the inner tube section 221 and the tube section 223,
A through hole 225 and through holes 226 and 227 are formed coaxially with the hole in the inner tube portion 222 . Reference numeral 3 denotes an internal electrode having a pin 31 as a contact and a screw portion 32 at one end, and a slot 33 is formed at the other end of the internal electrode 3.

Furthermore, a ring-shaped sealing protrusion 34 is provided near the slot of the internal electrode 3 . 4 is a junction, and 5 is a compensation electrode into which a temperature sensing resistor 51 is inserted.

This compensation electrode 5 is made of a metal material such as stainless steel to provide a liquid earth. 6 is bag nut, 7 is silver bar,
8 is a pin socket.

The detection unit DET is assembled as follows. First, the silver bar 1 is adhesively fixed in the through hole 213 of the bottom tube 210 so that its lower end is located below the through hole 213. Further, the pin socket 8 is inserted into the hole of the inner tube part 221 and fixed by adhesive. Next, the inner tube portion 221 is inserted into the through holes 211 and 212.
The male tube 210 with the bottom and the lid 220 are assembled so that the upper part of the tube 222 fits in, and the circumferential surface of the lid 220 fits into the circumferential surface of the row tube 210 with the bottom, and the combined portion of the bottom is fixed with adhesive. Furthermore, the measurement electrode 1 is inserted into the inner tube part 221 of the container 2 with the pin 102 facing upward, and is attached using the cap nut 6 so that the electrode film 101 is exposed from the through hole 61. Next, the internal electrode 3 is inserted into the container 2 through the through hole 227 with the pin 31 facing upward, and the screw portion 32 is inserted into the upper screw portion 214.
Attach using. The slot 33 is provided for attachment using a screwdriver. Through this screw connection, the pin 31 and the silver rod 1 come into contact, and the two become electrically conductive. The juncture 4 is pushed into the receiving hole 226. Since it is not glued, it can be attached and detached at will. Through hole 2
The compensation electrode 5 is inserted and bonded to 25. A lead wire connected to the temperature measuring resistor 51 disposed within the compensation electrode 5 and a lead wire (not shown) directly connected to the compensation electrode 5 are
It is led to the upper part of the container 2 through the inner tube part 222. Further, an internal liquid 230 is introduced into the container 2 through a through hole 215 connected to a male tank (not shown). This detection part D
In ET, the output signal of the measuring electrode 1 appears on the pin socket 8, and the output signal of the internal electrode 3 appears on the silver bar 7. Next, the signal converter CON will be explained.

In this signal conversion unit CON, the lower end of 9 is the detection unit DE.
The force cylinder 10 is adhesively fixed to the container 2 of T, and 10 is a plate adhered to the upper part of this outer cylinder 9. This missing cylinder 9 and container 2
The adhesion between the base plate 10 and the plate 10 is performed to form a good seal. 11 is a plurality of connector pins (only one is shown in the figure) implanted in the plate 10, 12
13 is an impedance conversion circuit block, and 13 is a stud for arranging this circuit block 12 in the cutout tube 9.

FIG. 3 shows the electrical configuration of the signal converter CON mainly including the circuit block 12. In this figure, A is a differential amplifier, R, ~R are resistors, C1 to C4 are capacitors, L, , L are power supply lines for differential amplifier A,
L, is the output signal line of the differential amplifier A, L4 is the common line, L is the output signal line of the comparison electrode, and L6 is the earth line. The resistors Rl and R connected in series are connected to the non-inverting input terminal side of the differential amplifier A. A resistor R connected in series with the resistance temperature detector 51 is a differential amplifier A.
It forms a negative feedback circuit. Further, the resistor R4 alone constitutes a negative feedback circuit of the differential amplifier A. A resistor R, is connected between the inverting input terminal of the differential amplifier A and the common line L4. A capacitor C is connected between the connection point of the resistors Rl, R, and the common line L4, and a differential amplifier A
A capacitor C is connected between the inverting input terminal and the non-inverting input terminal of. The capacitors C, , C4 are connected between the auxiliary electrode 5, the common line L4, and the ground line L6, respectively. With this kind of circuit configuration,
Resistor R1 and capacitor C1 constitute a filter for noise coming in from the measurement electrode 1 (pin socket 8) side, and resistor R and capacitor C constitute a filter for spike noise coming in from power supply line L, L. I will do it. In addition, resistors R, ~R5, resistance temperature sensor 51
constitutes a circuit for compensating for the change in the potential of the glass electrode film 101 in proportion to the absolute temperature. The operation of this signal converter CON is as follows. Measuring electrode 1 applied to one end of resistor R via pin socket 8
The output signal passes through a filter consisting of a resistor R and a capacitor C1, and then is applied to the non-inverting input terminal of the differential amplifier A via a resistor R2. Since the differential amplifier A to which the temperature compensation circuit is added constitutes a voltage follower with high input impedance, the signal (PH signal) indicating the pH value of the test liquid that is error-free and temperature-compensated is the signal It appears on line L. Next, the socket section SOC will be explained.

In this socket SOC, 14 is a cap nut, 15
is a socket body attached to the signal converter CON by a cap nut 14. Reference numeral 16 designates a plate adhesively fixed within the socket body 15 so as to face the plate 11 of the signal converter CON, and 17 designates a number of connector sockets (only one is shown) implanted in the plate 16.

This connector socket 17 is connected to a connector pin in the signal converter CON. Reference numerals 18 and 19 designate a gasket and a gasket retainer for fixing the cable CC, and 20 represents an O-ring disposed at the joint between the socket portion SOC and the signal conversion portion CON.

This O-ring 20 is provided so that the inside of the probe AA and the male part are completely sealed when the assembly is completed. The recorder BB includes an adjustment section ADJ that performs zero adjustment, span adjustment, and power supply, and a recording section REC that records the output of this adjustment section ADJ. This recorder B
The circuit configuration of B is shown in FIG. In the figure, lines L and L6 correspond to lines L1 to L6 in FIG. 3, respectively. Further, A1 is a differential amplifier whose non-inverting input terminal is connected to the common line L4, VR is a variable resistor serving as the input resistance of differential amplifier A, R6 is a negative feedback resistor of differential amplifier A1, El, E2 are a negative power source and a positive power source, each of which has one end connected to the common line 24. The outputs of the power supplies El, E, are given to the power supply terminals of the differential amplifier A1, and are also given to the power supply lines L1, L2. VE is a variable voltage source connected between the common line L4 and the signal line L. In this circuit, the signal line L
, to the differential amplifier A1 is zero-adjusted by the variable voltage source VE, span-adjusted by the variable resistor R, and recorded in the recording section REC. The ground line L6 is always grounded at the adjustment unit ADJ when the test liquid is not grounded. The cable CC connects the valley lines L1 to L6 of the signal conversion unit CONO and each line L, to L6 of the adjustment unit ADJ.

The shield of the cable CC is grounded at the adjustment section ADJ. The device of the present invention configured in this manner has the following advantages.

First of all, there is a signal converter CO in the PH measurement probe AA.
Since it incorporates N, there is no need to provide a separate converter, and the overall configuration becomes simple.

Second, the output of the glass electrode, which has an extremely high output impedance, is immediately converted into a signal by the signal converter CON in the PH measurement probe AA, and this converted signal is given to the cable CC. don't need anything. Furthermore, since the detection section DET and the like are replaced at the connector downstream of the signal conversion section C, which does not cause any problem even if the insulation deteriorates, handling is easy. As described above, according to the present invention, it is possible to realize a simple PH measuring device with a simple overall configuration.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the device of the present invention, Fig. 2 is an exploded view showing the detection section in the PH measurement probe, and Fig. 3 is a P
H An electric circuit diagram showing the circuit configuration of the signal conversion section in the measurement probe. Figure 4 is an electric circuit diagram showing the circuit configuration of the adjustment section in the recorder.〇AA...Measuring probe, BB
... Recorder, CC ... Cable, 1.
...Measurement electrode, 3...Internal electrode (comparison electrode, 51...Resistance temperature detector, DET...
Detection section, CON... Signal conversion section, SOC...
...Socket section, ADJ...Adjustment section, REC
・・・・・・Record Department.

Claims (1)

[Claims] 1. A detection section comprising a pH measurement probe, a recorder, and a cable connecting these, and having a measurement electrode, a reference electrode, and a resistance temperature sensor, and a detection section that converts the output of the measurement electrode into a signal and converts the The pH measuring probe is composed of a signal converting section that uses the signal converting section to perform temperature compensation, and a socket section that is detachably coupled to the signal converting section and receives the output of the signal converting section via a connector. In the pH measuring device, the recorder is constituted by an adjustment section that performs zero adjustment and span adjustment of the output and supplies power to the signal conversion section, and a recording section that records the output of this adjustment section. an outer container that houses the measurement electrode in its inner tube portion so that the glass electrode film is exposed at the bottom thereof; and an internal liquid contained in the space within the outer container;
a liquid junction section detachably disposed at the bottom of the external container through a through hole at the bottom of the external container so that one end comes into contact with the internal liquid; The internal electrode of the reference electrode is configured to be removably screwed to the detection unit so as to be placed in the internal liquid, and the cable is connected to each line of the signal conversion unit and the adjustment unit. A pH measuring device characterized in that the lines are connected and the shield is grounded at the adjusting section.