JP6205775B2 - Water quality measurement method - Google Patents

Description

  The present invention relates to a method for measuring the quality of sample water such as pure water and ultrapure water, and more particularly to a method for measuring the quality of water sampled from a plurality of main lines with a common water quality measuring device. The present invention relates to a method particularly suitable for measuring the number of fine particles in pure water or ultrapure water.

  For cleaning the silicon wafer substrate as an electronic component, cleaning similar to RCA cleaning is performed, and high-concentration chemicals and detergents and pure water and ultrapure water for rinsing them are used.

  In recent years, miniaturization of semiconductor devices has progressed, and the management value of the number of fine particles in ultrapure water has also been miniaturized. Originally, it would be ideal to manage each of the pipes supplied to the washing machine with a particle meter, but since the particle meter that monitors fine particles online is expensive, increase the number of instruments. This is not preferable because it causes an increase in cost. For this reason, it is common to use a particle meter only for monitoring the central pipe. Therefore, it is required to monitor the number of fine particles online for as many pipes as possible at low cost.

  It has been conventionally performed to measure water quality by introducing water flowing through a plurality of lines into a common measuring device through a preparative valve. For example, in Patent Document 1, ultrapure water from an ultrapure water line and concentrated water obtained by concentrating this ultrapure water using a reverse osmosis membrane separator are switched by a valve and introduced into a common measuring device for analysis. Things have been done. Examples of analysis items include metal ion concentration, resistivity, fine particle count, TOC concentration, silica concentration, and dissolved oxygen concentration (paragraph 0049).

  Patent Document 2 describes that a dissolved gas concentration of gas dissolved water from gas dissolving modules installed in two series in parallel is measured with a common dissolved gas concentration meter. Gas dissolved water from each gas dissolution module is switched by a valve and introduced into a dissolved gas concentration meter.

  In Patent Document 3, as a water quality evaluation method for analyzing the amine concentration in ultrapure water, the effluent water from the silicon particle packed columns provided in parallel in three series is switched by a valve and introduced into a common hydrogen concentration meter. It describes the measurement of dissolved hydrogen concentration.

JP2010-44022 JP 2009-95778 A JP2011-214879A

  When water in multiple lines is switched by a valve and introduced into a common water quality measurement device for water quality measurement, if part of the water remaining in the water sampling channel is mixed into the sample water, the measurement accuracy decreases. To do.

  An object of this invention is to raise the measurement precision in the case of measuring the quality of the water which flows through several main lines with a common measuring apparatus.

  The water quality measurement method of the present invention is a water quality measurement method in which water is collected from each of a plurality of main lines and introduced into a common water quality measuring instrument to measure the water quality. It is divided into an introduction line and a blow line, and water from the introduction line is introduced into the water quality measuring device via a switching valve.

In the present invention, it is preferable to set the flow rate _{F 3} of the blow line 10 to 60% of the flow rate _{F 1} of the collection line.

  In the present invention, it is preferable that water is always blown from the main line that has not reached the water quality measurement timing, flowing through the sampling line and the blow line.

The ratio F ₄ / F ₁ of the blow water flow rate F ₄ from the main line that is not at the time of water quality measurement and the water sampling flow rate F ₁ from the main line that is measuring the water quality may be 0.2-2. preferable.

  In the present invention, it is preferable to discard the data of the water quality measuring device for a predetermined time after the switching of the switching valve.

  In the water quality measurement method of the present invention, water sampled from a plurality of main lines is introduced into a common water quality measurement device, and the water quality is measured. Therefore, one water quality measurement device is sufficient, and the equipment cost is reduced.

In the present invention, the water collected from the main line is divided into the blow line and the introduction line, and the water in the introduction line is introduced into the water quality measuring device via the switching valve. Moreover, water is always blown from this blow line. For this reason, water does not stay in the blow line, and the accuracy of the water quality measurement value increases. Note that the measurement accuracy is sufficiently high by setting the blow water flow rate F ₃ to 10% or more, particularly 20% or more, of the sampling flow rate F ₁ from the main line. Also, the F ₃ by the following in particular 50% to 60% of the F _1, it is possible to reduce the blow quantity of water wasted.

In the present invention, it is preferable to always collect water from the main line that has not reached the water quality measurement time and to flow water through the water collection line and the blow line. Thereby, when the main line used as a water quality measurement object is switched, the amount of water and water pressure of a water sampling line are prevented from changing rapidly, and dust generation by vibration etc. is prevented. With particular 0.8 times 0.2 times or more of the non-measurement adopted water flow rate at the time of the measurement of blow water flow rate F ₄ at F _1, the effect is remarkable. Also, the F ₄ 2 times the F ₁ or less, particularly by 1.2 times or less, it is possible to reduce the blow quantity of water wasted.

  In the present invention, when the switching valve is operated so as to switch the measurement target main line, it is preferable to reject the water quality measurement data for a predetermined period thereafter. This is because there is a possibility that dust generation may occur as the valve body of the switching valve slides.

It is a line lineblock diagram showing the water quality measuring method concerning an embodiment. It is explanatory drawing of the flow of the water in embodiment.

  Hereinafter, embodiments will be described with reference to FIGS. In this embodiment, the number of fine particles of water (ultra pure water in this embodiment) A and B flowing through the main pipes 1 and 2 as the main line is measured by one common fine particle meter 16. In this embodiment, a laser light scattering type is used as the particle counter 16. The particle size to be measured by this particle meter is about 50 to 200 nm. However, the particle counter is not limited to this, and a light blocking method, off-line analysis, or the like can also be used.

  The water A flowing through the main pipe 1 is separated by the water sampling line 3 and can be discharged out of the system through the blow line 4, the flow meter 5, and the valve 6. The water B flowing through the main pipe 2 is separated by the water collection line 10 and can be discharged out of the system through the blow line 11, the flow meter 12, and the valve 13.

  The water sampling line 3 branches into the blow line 4 and the introduction line 7. The introduction line 7 is connected to the first introduction port of the three-way valve 8. The water sampling line 10 branches into the line 11 and the introduction line 14. The introduction line 14 is connected to the second introduction port of the three-way valve 8.

  Water from the outlet of the three-way valve 8 is introduced into the fine particle meter 16 through the line 15, and then the flow rate is measured by the flow meter 17, and then discharged out of the system through the valve 18.

  When measuring the number of fine particles of water A flowing through the main pipe 1, as shown in FIG. 2A, the three-way valve 8 communicates with the lines 7 and 15, and the water from the water sampling line 3 passes through the lines 7 and 15. Then, water is passed through the fine particle meter 16 and the flow meter 17 to measure the number of fine particles and the flow rate. At this time, most of the water from the water sampling line 3 is sent to the line 7, but a part of the water flows to the blow line 4 and is discharged out of the system. Further, water is always supplied from the main pipe 2 to the lines 10 and 11 and discharged out of the system.

When performing quality measurements of water A, if the water flow rate adopted by the line 3 and F _1, a sample water flow from the line 7 to the flow meter 15 and F _2, the blow flow from line 4 was F _3, F it is preferred to ₃ with 10% to 60%, especially 20 to 50% of the _{F 1.}

  By blowing a part of the water from the water collection line 3 to the line 4 in this way, the water does not stay in the line 4, so that the staying water is mixed (diffused) into the sample water to the line 7. Is prevented. In this way, water quality measurement (fine particle concentration measurement) can be performed with high accuracy by preventing mixing of stagnant water from the line 4.

Further, as described above, while the water A is sampled from the main pipe 1 and measured, the water B is always supplied to the lines 10 and 11 from the main pipe 2 that is not in the measurement timing and blown. At this time, the blow water flow rate F ₄ through the lines 10 and 11 is set to be substantially the same as F ₁ , specifically, F ₄ / F _{1 is set} to 0.2 to 2, particularly 0.8 to 1.2. It is preferable to do. This is because when the three-way valve 8 is switched from the state of FIG. 2A as shown in FIG. 2B to introduce water B from the main pipe 2 into the particle meter 16, This is to prevent the flow rate and water pressure from fluctuating rapidly and to prevent particulate generation due to vibration.

In FIG. 2 (a), water A is introduced from the main pipe 1 into the particle counter 16 and the water quality is measured. However, as shown in FIG. 2 (b), water B is introduced into the particle analyzer 16 from the main pipe 2. The water quality is preferably measured under the same conditions as described above. In FIG. 2 (b), water B is introduced into the particle counter 16 via lines 10, 14, 15. Water A is blown through lines 3 and 4. The flow rates F _{1 to} F ₄ are the same as in the case of FIG.

  When water sampling from the main pipe 1 is switched to water sampling from the main pipe 2, and when water sampling from the main pipe 2 is switched to water sampling from the main pipe 1, a predetermined time (for example, 10 to 20) from the switching. Minute, particularly about 15 minutes), it is preferable to reject the particulate measurement data. This is because immediately after switching, there is a possibility that dust generation may occur as the valve body slides when the three-way valve 8 is switched.

  The present invention is suitable for measuring the number of fine particles in pure water or ultrapure water, but for measuring other water quality items (for example, metal ion concentration, resistivity, TOC concentration, silica concentration, dissolved oxygen concentration). Is also applicable. When measuring the number of fine particles in pure water or ultrapure water, the amount of water passing through the fine particle meter is preferably about 0.5 to 2 L / min.

  In the present invention, it is preferable that at least the water contact surfaces of the pipe and each device are made of a fluororesin.

  Hereinafter, examples and comparative examples will be described.

[Example 1]
In FIG. 1, pipes and valves whose inner surfaces were all coated with fluororesin were used. Ultrapure water having a fine particle count of 0.5 particles / mL was circulated through the main pipes 1 and 2 at 20 L / min.

First, water was collected from the main pipe 1 as shown in FIG. 2 (a), and the number of fine particles was measured for 45 minutes with a fine particle meter (K-LAMIC, manufactured by Kurita Kogyo Co., Ltd.) 16. At this time, F _{1 to} F ₄ were as follows. F ₃ is 50% of F ₁ .
F ₁ = 1.0 L / min
F ₂ = 0.5 L / min
F ₃ = 0.5 L / min
F ₄ = 1.0 L / min

  Thereafter, as shown in FIG. 2 (b), ultrapure water B was passed from the main pipe 2 to the particle counter 16 under the same conditions as described above, and the number of particles was measured over 45 minutes. This was repeated below. Table 1 shows the measurement result of the number of particles of the particle counter 16.

[Example 2]
In Example 1, the blow amount of water _{F 3} from the line 4 to reduce 10% of the _{F 1,} the _{F 1 ~F 4 F 1 = 0.55L} / min
F ₂ = 0.5 L / min
F ₃ = 0.05 L / min
F ₄ = 0.55 L / min
The number of fine particles was measured in the same manner except that. The results are shown in Table 1.

[Comparative Example 1]
In Example 1, the blow from the line 4 is not performed, and F _{1 to} F ₄ are set to F ₁ = 0.5 L / min.
F ₂ = 0.5 L / min
F ₃ = 0 L / min
F ₄ = 0.5 L / min
The number of fine particles was measured in the same manner except that. The results are shown in Table 1.

  As shown in Table 1, according to Example 1, the number of fine particles was not stable for 15 minutes after switching, but it was confirmed that the number of fine particles could be measured with high accuracy after 15 minutes.

  In Example 2, the time until the number of fine particles is stabilized is longer than that in Example 1. In Comparative Example 1, it took more time to stabilize, and the number of fine particles could not be accurately measured.

1, 2 Main piping (main line)
3,10 Sampling line 4,11 Blow line 7,14 Introduction line 8 Three-way valve 16 Particle counter

Claims (5)

In a water quality measurement method that collects water from multiple main lines and introduces it into a common water quality measuring instrument to measure the water quality,
Water is collected from the main line to the collection line, then divided into the introduction line and the blow line, and water from the introduction line is introduced into the water quality measuring device via a multi-way valve,
It is characterized by flowing water from the main line that is not timed for water quality measurement to the sampling line and the blow line and blowing it,
Each introduction line is connected to the inlet of the multi-way valve, and effluent water from the outlet of the multi-way valve is introduced into the water quality measuring device,
A water quality measuring method, wherein each blow line is provided with a valve. In claim 1, water quality measuring method characterized by the flow rate F ₃ of the blow line 10 to 60% of the flow rate F ₁ of the collection line.   3. The water quality measuring method according to claim 1 or 2, wherein water is constantly flowed from a main line that is not in a water quality measurement period to a sampling line and a blow line and blown. 0.2 according to claim 3, blow water flow rate F ₄ from the main line which is not a time water quality measurements, the ratio F _{4 /} F ₁ of the adopted water flow rate F ₁ from the main line that the water quality measurement 2. A method for measuring water quality, wherein In any one of claims 1 to 4, after switching of the multiway valve, for a predetermined time, the water quality measuring method characterized by rejecting data of the water quality measuring device.

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