JPH07209232A - Concentration sensor and apparatus for measuring concentration using the same - Google Patents

Abstract

PURPOSE:To facilitate measurement of the concentration of soap, for example, in a solvent being employed in dry cleaning liquid or the like. CONSTITUTION:The concentration sensor 100 being immersed into a solution in order to measure the concentration of a conductive substance in a solution based on the conductivity thereof is provided with a pair of electrodes 11, 12 being applied with a predetermined AC voltage. A pair of the electrodes 11, 12 are disposed concentrically while being spaced apart by a predetermined distance wherein the outer electrode 12 is provided with an air vent 12a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concentration sensor for detecting the concentration of a conductive additive in a solution based on the conductivity of the solution, and a concentration measuring device using the same.

[0002]

2. Description of the Related Art In the field of dry cleaning, a desired amount of dry cleaning detergent (hereinafter referred to as soap) is added to a petroleum-based or other organic chemical solvent (hereinafter referred to as dry cleaning solvent). .) Is mixed to adjust the detergency and other qualities of the dry cleaning liquid, and the conductivity of the dry cleaning liquid is controlled to prevent ignition due to electrification during drying or cleaning. . For this reason, it becomes necessary to measure the soap concentration in the dry cleaning liquid as needed in order to monitor whether or not the soap concentration is appropriate.

As a method for measuring the soap concentration in the cleaning solution, the Epton method for chemically determining the soap concentration and the conductivity measuring method for determining the soap concentration from the conductivity of the dry cleaning liquid are known.

However, the former has a problem that the measurement is troublesome. That is, in the case of the former, it requires a specialized technique and knowledge for measurement, and also requires time and cost, so that it has been difficult to use it in the field of dry cleaning.

On the other hand, the latter has a problem that sufficient measurement accuracy cannot be obtained. This point will be described in more detail.

In the latter case, the conductivity of the dry cleaning liquid is measured by inserting a pair of electrodes of a conductivity tester into the dry cleaning liquid and applying a voltage between these electrodes.
This is done by measuring the value of the current flowing between these electrodes.

FIG. 7 shows an example of a sensor portion of a conventional conductivity tester. The pair of electrodes 50, 55 formed on the sensor portion are two in number, each of which is composed of a pair of ring-shaped electrodes 50a, 50b, 55a, 55b, and these ring-shaped electrodes are arranged alternately. Appropriate AC voltage is applied between the electrodes 50a, 50b on one side and the electrodes 55a, 55b on the other side, and from the current value, the conductivity,
That is, the soap concentration in the dry cleaning liquid can be obtained.

However, in the latter measurement using the above conductivity tester, it is impossible to measure the concentration easily and with high accuracy. That is, since the dry cleaning liquid is easily ignited by static electricity, it is necessary to avoid applying a high voltage to it. Therefore, although a low voltage is applied between the pair of electrodes of the conductivity tester, generally, with a dry cleaning liquid having extremely low conductivity, a sufficient current cannot be taken out, and the required measurement accuracy cannot be secured. As a result, the soap concentration in the dry cleaning liquid cannot be adequately controlled, and the problem that the quality adjustment of the dry cleaning liquid is difficult and the risk of ignition of the dry cleaning liquid cannot be prevented in advance. There was a problem.

Therefore, the present invention provides a concentration sensor capable of simply and quickly measuring the concentration of a conductive additive such as soap mixed in an insulating solvent such as a solvent for dry cleaning, and a concentration measurement using the same. It is intended to provide a device.

[0010]

In order to solve the above problems, a concentration sensor according to a first aspect of the present invention is based on the conductivity of a solution prepared by mixing a conductive additive in an insulating solvent. A concentration sensor comprising a pair of electrodes to which a voltage is applied while being immersed in the solution in order to measure the concentration of the additive in the solution, wherein one of the pair of electrodes has a cylindrical outer shape. It is an electrode, and the other of the pair of electrodes is an inner electrode concentrically arranged in the outer electrode.

The concentration sensor according to a second aspect of the present invention is characterized in that the outer electrode is provided with an opening for venting air at the base side portion fixed relatively to the inner electrode. To do.

Further, the concentration measuring apparatus according to the third aspect of the present invention is a concentration sensor having a pair of electrodes immersed in a solution prepared by mixing a conductive additive in an insulating solvent, and a pair of concentration sensors. A determination device that electrically applies a voltage between electrodes to detect a current flowing between these electrodes, and electrically determines whether or not the concentration of the additive in the solution is within a predetermined range based on the detected current. Is a concentration measuring device integrally connected, one of the pair of electrodes is a cylindrical outer electrode, the other of the pair of electrodes is concentrically spaced apart in the outer electrode. The determination device includes a display unit for visually displaying the determination result, and the display unit is formed on the surface opposite to the connection position of the concentration sensor. .

[0013]

<Operation of the invention according to claim 1> In the concentration sensor of the present invention, one of the pair of electrodes is an outer electrode formed in a cylindrical shape, and the other is separated concentrically within the outer electrode. Since the inner electrodes are arranged in parallel, the area of the pair of electrodes facing each other can be increased while maintaining the size of the concentration sensor itself, and the distance between the facing surfaces of the pair of electrodes can be easily reduced. can do. Therefore, it is possible to dramatically increase the amount of current flowing between the pair of electrodes while keeping the concentration sensor itself small and keeping the voltage applied between the pair of electrodes low.
It is possible to measure the conductivity of the solution, which is the object to be measured, that is, the concentration of the conductive additive in the solution with high accuracy.

<Operation of the Invention According to Claim 2> In the concentration sensor of the present invention, since the outer electrode has an opening for venting air at the base side thereof, when the concentration sensor is dipped in a solution, Air can escape through the opening. Therefore, the solution as the measured object can be introduced between the pair of electrodes easily and reliably, and the accuracy of the concentration measurement can be kept constant.

<Operation of the Invention According to Claim 3> In the concentration measuring device of the present invention, one of the pair of electrodes is an outer electrode formed in a cylindrical shape, and the other is concentrically spaced inside the outer electrode. Since the inner electrodes are arranged in the same manner, the facing area of the pair of electrodes can be increased, and the distance between them can be easily reduced. Therefore, it is possible to increase the amount of current flowing between the pair of electrodes while keeping the concentration sensor part small and the voltage applied between the pair of electrodes low. The concentration of the conductive additive therein can be measured with high accuracy.
In this case, since the concentration sensor and the determination device are integrally connected, and the determination result display portion provided in the determination device is formed on the opposite side of the connection position of the concentration sensor, With the concentration sensor attached to the solution that is the measurement object, the display unit showing the determination result can be easily and quickly observed from above the solution.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a density sensor 100 according to an embodiment.
3 is a diagram showing a concentration measuring device including a tester main body 200 which is connected to the concentration sensor 100 and displays a conductivity based on an output of the concentration sensor 100. FIG.

The concentration sensor 100 includes an electrode portion 10 on the tip side.
And a holder side 20 on the handle side. The electrode unit 10 includes an inner electrode 11 and an outer electrode 12, which are a pair of stainless steel concentric electrodes, and an alternating voltage from the tester main body 200 is applied between the electrodes 11 and 12. One of these outer electrodes 12 has a small opening 12a for venting air at the end on the holder 20 side. The holder portion 20 supporting the electrode portion 10 is also made of stainless steel, and a level mark 21 is engraved on the surface of the holder portion 20 at the end portion on the electrode portion 10 side and a knurl 22 for preventing slippage on the opposite side.
Are formed.

The tester main body 200 is a normal conductivity measuring tester, and is connected to the concentration sensor 100 via a connector 30 and a coaxial cable 40. Briefly describing the structure of the tester main body 200, the AC power supply 210 generates an AC voltage to be supplied to the inner electrode 11 and the outer electrode 12 of the concentration sensor 100, and the ammeter 220
Measures the current value flowing between these electrodes 11, 12. The measurement result of the ammeter 220 is converted into conductivity and displayed on a display device (not shown). The resistor group 30
Is for switching the measurement range. In addition,
In this embodiment, the mounting position of the display device is not particularly limited, and it is provided at any position on the housing surface of the tester main body 200. Another embodiment (corresponding to the invention of claim 3) in which the mounting position of the display device is particularly preferable will be described later.

The conversion of the electric current value into the electric conductivity in the tester main body 200 is performed by obtaining the product of a predetermined proportional constant and the electric current value. As is well known, such a proportionality constant has a parameter between the distance between the facing surfaces of the inner electrode 11 and the outer electrode 12 and the area where they face each other. Therefore, an experiment based on these values is performed in advance. Has been decided.

A method for measuring the soap concentration in the dry cleaning liquid using the apparatus shown in FIG. 1 will be briefly described.

First, a sample of the dry cleaning liquid is taken out to a beaker or the like, the electrode portion 10 of the concentration sensor 100 is immersed in the dry cleaning liquid, and the portion from the tip of the electrode portion 10 to the level mark 21 is immersed in the dry cleaning liquid. Lower to position. At this time, as shown in FIG. 2, air accumulated between the inner electrode 11 and the outer electrode 12 escapes from a pair of openings 12a provided in the outer electrode 12,
A gap portion (clearance portion) 13 between the electrodes 11 and 12 is filled with the dry cleaning liquid.

Next, the tester main body 200 is reset to start current measurement, that is, conductivity measurement, and the conductivity is read when the measured value becomes stable.

After that, the concentration of soap in the dry cleaning liquid is read from the graph of the calibration curve prepared in advance (for example, the graph of FIG. 3). This calibration curve is determined by preparing various dry cleaning liquids in which soap of known concentration is mixed in advance and repeatedly measuring the conductivity thereof with the apparatus of FIG. The dry cleaning liquid is composed of petroleum-based or other organic chemical solvent, and soap is added from the viewpoint of its cleaning ability and prevention of recontamination. This soap has the function of increasing the conductivity of the dry cleaning liquid to suppress ignition due to static electricity, but conversely it can be said that the soap concentration in the dry cleaning liquid can be obtained from the conductivity. The calibration curve is prepared for the purpose of converting the conductivity into the soap concentration, and is determined according to the types of the dry cleaning solvent and the soap, and the temperature of the dry cleaning liquid. In addition,
Since the temperature of the dry cleaning liquid is usually controlled separately, it is practically sufficient to prepare a calibration curve that matches the control temperature.

The structure of the density sensor 100 shown in FIG. 1 will be described below in more detail.

FIG. 4 is a vertical sectional view of the density sensor 100 of the embodiment. The cylindrical outer electrode 12, which is the electrode on one side of the electrode portion 10, is screwed to one end of the hollow holder portion 20. Further, the outer electrode 12 has a pair of openings 12a, 1 facing each other at the holder 20 side end.
2a is formed. These openings 12a, 12a
Are provided for venting air between the inner electrode 11 and the outer electrode 12, as described above. On the other hand, the electrode part 10
The columnar inner electrode 11, which is the other electrode, is screwed to one end of the conductor rod 23 passing through the center of the holder portion 20. The conductor rod 23 is firmly fixed by the insulating sleeve 24 in the cavity of the holder portion 20 with their central axes aligned. As a result, the inner electrode 11
Is completely insulated from the outer electrode 12 and the holder portion 20, and the inner electrode 11 and the outer electrode 12 are aligned and fixed to each other so that the tip surfaces (left end in the drawing) of the inner electrode 11 and the outer electrode 12 are kept at a predetermined distance. It That is, a clearance portion 13, which is a gap into which the dry cleaning liquid to be measured is introduced, is formed between the electrodes 11 and 12.

A connector 30 that enables electrical connection to the tester body 200 is screwed into the right end of the holder portion 20 in the drawing. With this connector 30, the holder 2
0 (outer electrode 12) is connected to the ground side of the coaxial cable 40 shown in FIG. 1, and the conductor rod 23 (inner electrode 11) is connected to the core side of the coaxial cable 40.

FIG. 5 shows each electrode 1 constituting the electrode section 10.
1 shows a vertical sectional view of 1. FIG. 5A shows the outer electrode 1.
2 is a sectional view of the inner electrode 11, and FIG. 5B is a sectional view of the inner electrode 11. As shown in FIG. 5A, the cylindrical outer electrode 12 has a pair of openings 12 with a diameter of about 4 mm for removing air.
a and 12a are formed. A female screw 12b is formed on the right end of the outer electrode 12 in the drawing. The female screw 12b is screwed with a screw thread formed at one end of the holder portion 20. As shown in FIG. 5B, a female screw 11b is also formed on the right end of the cylindrical inner electrode 11 in the drawing. The female screw 11b is formed on one end of the conductor rod 23. Screw together. When the inner electrode 11 and the outer electrode 12 are attached to the holder portion 20 side, the inner electrode 1
1 is housed in the outer electrode 12, both electrodes 11, 1
A cylindrical clearance portion having a predetermined diameter, length and thickness is formed between the two. At this time, the end surfaces of the electrodes 11 and 12 on the left side of the drawing are aligned with each other. In the case of the embodiment, the distance between both electrodes 11 and 12 is about 1 mm, and the diameter and length of the inner electrode are about 1 cm and 5 cm, respectively. Therefore, the diameter, length and thickness of the cylindrical clearance portion are about 1 cm, 5 cm and 1 respectively.
mm.

In the concentration sensor 100 of the above embodiment, the conductivity is measured in the relatively thin and wide clearance portion 13 formed between the concentric inner electrode 11 and the outer electrode 12. That is, the distance between the electrodes 11 and 12 can be shortened without enlarging the density sensor 100 itself, and the area where these electrodes face each other can be increased. Therefore, the voltage applied between the electrodes 11 and 12 is reduced to maintain the safety, and
The amount of current flowing between the two can be dramatically increased,
The soap concentration and the like in the dry cleaning liquid can be extremely accurately determined by the small concentration sensor 100.

At this time, since the cylindrical outer electrode 12 is provided with the pair of openings 12a, 12a, when the concentration sensor is immersed in the dry cleaning liquid, air can escape from the openings. Therefore, both electrodes 11, 1
It is possible to easily prevent the air remaining between the two from deteriorating the accuracy of the concentration measurement.

FIG. 6 is a diagram showing a concentration measuring apparatus according to another embodiment of the present invention. 6 (a) is a front view, FIG. 6 (b) is a plan view, and FIG. 6 (c) is a side view. This concentration measuring device is a type of device in which the concentration sensor 100 of the concentration measuring device of FIG. 1 and a tester main body 200 are integrally connected.

As shown in the figure, the concentration measuring device of the embodiment is
It is composed of a density sensor unit 1100 and a tester main body 1200. The electrode unit 10 similar to that described in FIG. 5 is attached to the tip of the concentration sensor unit 1100. In addition, a level mark 21 is provided near the mounting position of the electrode portion 10.
Are formed.

Inside the tester main body 1200, the battery 1
200a and electric circuit 1200b are incorporated. Among them, the electric circuit 1200b is an oscillating circuit that generates an AC voltage to be supplied to the electrode unit 10, an amplifier that converts a current from the electrode unit 10 into a voltage and amplifies it, and a voltage output of the amplifier has a predetermined voltage value. A plurality of comparators for comparison are provided. On the side surface of the tester main body 1200, the electric circuit 12
Push-button switch 12 to activate 00b
00c is provided (see FIG. 6C). further,
The upper surface of the tester body 1200, that is, the concentration sensor 110
On the side where 0 is not attached, LE which is a display part on the surface
A display device 1200e in which D1200d are arranged is provided (see FIG. 6B).

LED 12 constituting the display device 1200e
Of 00d, the center three are green, and the two ends are red and yellow, respectively. Green LE in the center
The lighting of D indicates that the soap concentration is appropriate, and the lighting of the red LED indicates that the soap concentration is too low.
Illumination of the yellow LED indicates that the soap concentration is too high. In this case, the soap density at the boundary between the red LED and the green LED is 0.3%, the soap density at the boundary between the center and the green LEDs at both ends is 0.5% and 0.8%, respectively, and the green L
The soap concentration at the boundary between the ED and the yellow LED is set to 1.0%. The control of the lighting state of the LED 1200d that displays the soap concentration is performed by appropriately setting the comparison voltage supplied to the plurality of comparators of the electric circuit 1200b and supplying the output of this comparator to the LED driver.

In the concentration measuring device of the above embodiment, the concentration sensor unit 1100 and the tester main body 1200 are integrally connected, and the LED 1200d which is a display unit provided in the tester main body 1200 is the concentration sensor unit 1100.
Since it is formed on the opposite side of the connection position of, the LED 1200d, which is the display unit, can be easily and quickly observed from above the dry cleaning liquid while the concentration sensor unit 1200 is immersed in the dry cleaning liquid, which is the measured object. Therefore, the workability of detecting the soap concentration can be improved.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made. For example, the inner electrode 11 of the embodiment
Also, instead of the outer electrode 12, various concentric electrodes can be used. The pair of electrodes may be composed of an elliptic cylinder and a cylinder. However, from the viewpoint of processing accuracy, measurement accuracy, and the like, it is preferable that the pair of electrodes be composed of a perfect circle cylinder and a cylinder.

Further, each electrode may have a multi-layer structure. For example, a cylindrical electrode electrically directly connected to the inner electrode 11 can be attached to the outer side of the outer electrode 12.

Further, although the outer electrode 12 of the embodiment has a perfect cylindrical shape, the outer electrode 12 may have any outer peripheral shape as long as the cylindrical clearance portion 13 is formed, and the inner electrode 11 has a hollow portion. Is also optional. This is because it does not affect the result of conductivity measurement.

Further, although both electrodes 11 and 12 are made of stainless steel in the embodiment, both electrodes can be made of various conductive materials. However, it is preferable to use a steel material such as stainless steel from the viewpoints of resistance to a solvent for dry cleaning and the like and the robustness that the clearance portion 13 is not easily deformed.

Further, although the electrode portion 10 is fixed in the above embodiment, the electrode portion having clearance portions of various diameters, lengths and thicknesses may be replaceably attached.

Further, in the above embodiment, the circular opening 12a is formed.
Is formed at the base of the outer electrode 12, but the opening 12a
The shape and position of are arbitrary. However, from the viewpoint of measurement accuracy, it is preferable to form the opening 12a while avoiding the clearance 13 between the electrodes 11 and 12.

Further, the air vent opening 12a may be formed in the holder portion 20. However, the concentration tester 100
From the viewpoint of ease of cleaning itself, it is preferable to form such an opening in the removable outer electrode 12 on the tip side of the concentration tester 100.

Further, although the soap concentration in the dry cleaning liquid was measured in the apparatus of the embodiment, the concentration of the additive in various solutions prepared by mixing the conductive additive in the insulating solvent was measured in the same manner as above. can do. However, by using it in the field of dry cleaning using insulating solvents such as petroleum-based solvents, tetrachloroethylene, and other organic chemical solvents, the cleaning quality can be easily kept constant and the risk of ignition can be effectively prevented. There is.

Further, in the concentration detecting apparatus shown in FIG. 1, the conductivity is once obtained and then the soap concentration is obtained, but the value of the soap concentration is automatically determined directly from the detected current or the like and displayed. You can also

Further, in the above embodiment, it is assumed that the temperature condition is controlled separately from this device, but a thermistor may be attached to the end face of the inner electrode 11 to monitor the temperature of the dry cleaning liquid. . in this case,
It is also possible to calibrate the measured concentration based on the measured temperature.

Further, in the above embodiment, a set of 5 LEDs is used.
Although the display unit is configured by 1200d, the display unit may be configured by two LEDs that display the excess concentration and the insufficient concentration, and the display unit may be configured by an analog display meter.

[0047]

【The invention's effect】

<Effect of the Invention According to Claim 1> In the concentration sensor of the present invention, the pair of electrodes is an outer electrode formed in a cylindrical shape and an inner electrode separation arranged concentrically with respect to the outer electrode. Therefore, it is possible to dramatically increase the amount of current flowing between the pair of electrodes while keeping the density sensor itself small and keeping the voltage applied between the pair of electrodes low. The conductivity of a solution, that is, the concentration of the conductive substance in the solution can be measured with high accuracy.

<Effect of the Invention According to Claim 2> In the concentration sensor of the present invention, since the outer electrode has an opening at the base thereof, when the concentration sensor is immersed in the solution, air is released from this opening. Therefore, the accuracy of concentration measurement can be kept constant.

<Effect of the Invention According to Claim 3> In the concentration measuring device of the present invention, in the concentration measuring device of the present invention, the pair of electrodes are concentrically spaced from the outer electrode formed in a cylindrical shape. Since the inner electrodes are spaced apart from each other, the amount of current flowing between the pair of electrodes can be reduced while keeping the concentration sensor part small and keeping the voltage applied between the pair of electrodes low. The concentration of the conductive additive in the solution, which is the object to be measured, can be measured with high accuracy. In this case, since the concentration sensor and the determination device are integrally connected, and the display unit for the determination result provided in the determination device is formed on the surface opposite to the connection position of the concentration sensor. With the concentration sensor attached to the solution to be measured, the display section showing the determination result can be easily and quickly observed from above the solution,
The workability of concentration measurement can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a concentration measuring device including a concentration sensor and a tester according to an embodiment.

FIG. 2 is a diagram showing a method of using the device of the embodiment.

FIG. 3 is a graph showing an example of a calibration curve.

4 is a vertical cross-sectional view of the density sensor of FIG.

5 is a vertical cross-sectional view of a main part of the density sensor of FIG.

FIG. 6 is a diagram showing a concentration measuring device of an example.

FIG. 7 is a diagram showing a conventional example.

[Explanation of symbols]

 11, 12 inner electrode and outer electrode (a pair of electrodes) 12a opening 100 temperature sensor 200 tester main body 1200 determination device 1200d LED (display unit)

Claims (3)

[Claims] 1. To measure the concentration of an additive in a solution obtained by mixing a conductive additive in an insulating solvent based on the conductivity of the solution, the solution is immersed in the solution and a voltage is applied. In the concentration sensor having a pair of electrodes, one of the pair of electrodes is an outer electrode formed in a tubular shape, and the other of the pair of electrodes is concentrically spaced within the outer electrode. A concentration sensor characterized in that it is an inner electrode that is arranged as. 2. The concentration sensor according to claim 1, wherein the outer electrode is provided with an opening for air bleeding at a root side portion fixed relatively to the inner electrode. 3. A concentration sensor comprising a pair of electrodes immersed in a solution in which a conductive additive is mixed in an insulating solvent, and a voltage is applied between the pair of electrodes to apply a voltage between these electrodes. A concentration measuring device integrally connected to a determination device that detects a flowing current and electrically determines whether or not the concentration of the additive in the solution is within a predetermined range based on the detected current. The one of the pair of electrodes is an outer electrode formed in a tubular shape, and the other of the pair of electrodes is an inner electrode arranged concentrically in the outer electrode. The concentration measuring device is characterized in that the device includes a display portion for visually displaying the determination result, and the display portion is formed on a surface of the concentration sensor opposite to the connection position.