JPH05281132A - Apparatus for measuring particulate in liquid - Google Patents

Abstract

PURPOSE:To stabilize the detected signal and to improve measuring accuracy by providing a flow-rate adjusting valve in the draining flow path of a scattering cell through which sample liquid is made to flow and passing the sample liquid in the cell at the specified flow rate under the specified pressure. CONSTITUTION:When particulates in cleaning water are measured, the pressure of the cleaning water through a sample inlet port 1 is reduced to the specified pressure with a pressure regulating valve 2. A flow-rate-balance adjusting valve 21 is adjusted, and the fluid is divided so that the specified flow-rate is obtained in flow paths 10 and 20. The opening of a three-way valve 12 on the side of a flow path 30 is closed. The cleaning water, which is divided into the flow path 10 is supplied into a scattering cell SC as a sample through a flowmeter 11 and the three-way valve 12. Meanwhile, the cleaning water, which is divided into the flow path 20, is guided into a filter device 23 through a flow-rate-balance adjusting valve 21 and a flowmeter 22. The filtered cleaning water is supplied into the scattering cell SC as sheath flow liquid. At this time, a flow-rate regulating valve 3 is provided at the outlet port of the cell SC. The pressure in the cell SC is regulated so that the pressure is not extremely lower than the input pressure. Thus, the flow rate of the flowing sample liquid is kept constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring fine particles in liquid, and more particularly to a sheath flow type fine particle measuring apparatus.

[0002]

2. Description of the Related Art Since a large amount of extremely clean cleaning water is required in a semiconductor manufacturing process, it is necessary to keep the number of fine particles contained in a constant volume of cleaning water below a certain value.

As a conventional technique for measuring fine particles contained in the cleaning water, a part of the cleaning water is introduced into the scattering cell as sample water, and light from a tungsten lamp is irradiated as incident light at that time. The scattered light generated on the surface of the sample water is received by a photodetector, and based on this, the size and the number of fine particles in the sample water are measured.

However, according to the above-mentioned prior art, there is a non-detection region other than the scattered light detection region in the range where the incident light traverses the scattering cell, and the scattered light from this non-detection region is so-called. It becomes harmful as a background and makes it difficult to detect ultrafine particles. As a means for solving this, the applicant of the present application is applying for a utility model registration of a sheath flow type fine particle measuring device in liquid.

In such a fine particle measuring apparatus, it is preferable that the sample liquid flows through the scattering cell at a constant flow rate in order to stabilize the detection signal, and in order to prevent generation of bubbles that cause a measurement error. It is desirable that the sample liquid be kept at a predetermined pressure.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to allow a sample liquid in a sheath flow type liquid to flow a sample liquid through a scattering cell at a constant flow rate and a predetermined pressure.

[0007]

In order to achieve the above object, the present invention provides a flow rate adjusting valve in the discharge channel of the scattering cell through which the sample liquid flows.

[0008]

By providing the flow rate adjusting valve in the discharge passage connected to the outlet side of the scattering cell, the flow rate of the sample liquid flowing through the scattering cell can be made constant and kept at a predetermined pressure. As a result, the detection signal can be stabilized, the generation of bubbles can be prevented, and the measurement accuracy can be improved. In addition, since the flow rate adjusting valve is provided on the downstream side of the scattering cell, it is possible to prevent the scattering cell from being affected by dirt coming out of the valve.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. In the figure, 1 is a sample inlet for taking in cleaning water flowing to a cleaning line (not shown) of a semiconductor factory, for example. 2 is a pressure regulating valve disposed in the sample taken is connected to the inlet 1 sample inlet pipe 1a, since the pressure of the washing water in the washing in the line is high (e.g., 5Kg / cm ^3), vacuum into a predetermined pressure It functions as a source pressure control valve for operating.

Reference numeral 10 is a first flow path branched and connected to the outlet side of the pressure regulating valve 2, which is provided with a first flow meter 11 and a three-way valve (a three-way solenoid valve is shown) 12, the end of which is a scattering cell. It is connected to the sample injection nozzle (not shown) in the SC. The first flow path 10 supplies cleaning water, which has been depressurized to a predetermined pressure by the pressure control valve 2, to the scattering cell SC as a sample, and the flow rate of the sample flowing through the first flow path 10 is measured by the first flow meter 11. To be done.

Reference numeral 20 denotes a second flow passage 20 provided in parallel with the first flow passage 10, a flow rate balance adjusting valve 21 and a second flow meter.
22 and a filter device 23, the ends of which are connected to the sheath flow supply unit (not shown) of the scattering cell SC. The flow rate balance adjusting valve 21 is a valve for adjusting the balance of the liquid flow rates in the first flow path 10 and the second flow path 20 which are connected in parallel with each other. The second flow meter 22 measures the liquid flow rate of the second flow path 20, and the flow rate balance adjustment valve 21 is controlled based on the measurement result and the measurement result of the first flow meter 10. As the filter device 23, for example, a thin film filter having the capability of removing fine particles of about 0.05 to 0.1 μm is used. In the second flow path 20 configured as described above,
By filtering the cleaning water reduced to a predetermined pressure by the pressure control valve 2 by the filter device 23, pure water containing no impurities such as fine particles is obtained, and this filtered water is supplied to the scattering cell SC as a sheath flow liquid. ..

Reference numeral 30 is a third flow passage provided so as to connect between the point 24 between the filter device 23 and the scattering cell SC and the three-way valve 12, and 31 is the third flow passage 30. Is a check valve provided in. At the point 32 between the check valve 31 and the three-way valve 12,
The standard particle supply device 41 and the standard particle injection syringe 42 are connected in parallel with each other. The standard particle supply device 41 stores a high-concentration standard solution containing standard particles having a standard diameter, and is connected to the third flow path 30 via a check valve 43. The check valve 43 may be integrated with the standard particle supply device 41. The standard particle injection syringe 42 is driven by, for example, electric power, and is configured to suck the pure water or the standard solution by pushing the piston up and down and push out the pure water or the standard solution. 33 is an on-off valve and 44 is a piston.

Reference numeral 3 is a flow rate adjusting valve provided in the discharge flow path 4a connected to the outlet side of the scattering cell SC, and by maintaining the pressure in the scattering cell SC at a predetermined pressure, generation of bubbles in the cell SC is prevented. It is a valve to prevent. 4 is an outlet.

In the above structure, when measuring fine particles in the cleaning water, the cleaning water taken from the sample inlet 1 is depressurized to a predetermined pressure by the pressure adjusting valve 2. By appropriately adjusting the opening degree of the flow rate balance adjustment valve 21, the cleaning water is divided into the first flow path 10 and the second flow path 20 so as to have a predetermined flow rate ratio.

Since the opening of the three-way valve 12 to the side of the third flow passage 30 is closed, the washing water branched and introduced into the side of the first flow passage 10 passes through the first flow meter 11 and the three-way valve 12 and is used as a sample. Scattering cell
Supplied to SC. On the other hand, the cleaning water branched to the second flow path 20 side is supplied with the flow balance adjustment valve 21 and the second flow meter 22.
And reaches the filter device 23. Then, when passing through the filter device 23, predetermined filtration is performed, and the filtered water that has exited the filter device 23 becomes extremely clean liquid and is supplied to the scattering cell SC as a sheath flow liquid.

As described above, the flow control valve 3 is provided on the outlet side of the scattering cell SC, and this valve 3 makes the pressure in the scattering cell SC extremely lower than the intake pressure of the sample inlet 1. This prevents the occurrence of bubbles in the scattering cell SC and keeps the flow rate of the sample liquid flowing through the scattering cell SC constant. This enables highly accurate measurement.

Next, in order to calibrate the particle measuring device by supplying the standard solution diluted to a predetermined concentration to the scattering cell SC,
The on-off valve 33 is closed, the opening of the three-way valve 12 on the side of the third flow path 30 is closed, the main plug of the standard particle supply device 41 is opened, and a predetermined amount of standard solution is supplied via the check valve 43. 3 Introduce to the flow path 30 side. At this time, when the piston 44 of the standard particle injection syringe 42 is moved in the direction of arrow D, the standard solution is sucked into the syringe 42. Next, when the on-off valve 33 is opened, pure water from the filter device 23 is introduced into the third flow path 30 via the connection point 24,
It is introduced by suction into the standard particle injection syringe 42. And
By injecting a predetermined amount of pure water from the second flow path 20 into the syringe 42 with respect to the amount of the standard liquid from the standard particle supply device 41, the concentration of the standard particles in the syringe 42 is diluted and measured. It can be kept within the operating range of the device. In this case, by repeating the piston operation of the syringe 42 several times, it is possible to dilute to a predetermined concentration. An oscilloscope or a monitor indicating device may be used to determine whether or not the diluted standard solution is within the operating range of the measuring device.

Then, by operating the three-way valve 12, the third flow path 30
When the piston 44 is moved in the U direction with the scattering cell SC communicating with the scattering cell SC, the diluted standard solution in the syringe is diluted in the scattering cell SC and a predetermined calibration is performed. Two two-way valves may be used instead of the three-way valve 12.

[0019]

As described in detail above, according to the present invention, since the flow rate adjusting valve is provided on the downstream side of the scattering cell, the flow rate of the sample liquid flowing through the scattering cell is kept constant and the pressure is kept at a predetermined pressure. Can be kept. As a result, the detection signal can be stabilized, the generation of bubbles can be prevented, and the measurement accuracy can be improved. Further, since the flow rate adjusting valve is provided on the downstream side of the scattering cell, it is possible to prevent the scattering cell from being affected by the dirt coming out of the valve.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a device for measuring particles in a liquid according to the present invention.

[Explanation of symbols]

 3 ... Flow control valve, 4a ... Discharge passage, SC ... Scattering cell.

Claims (1)

[Claims] An apparatus for measuring fine particles in a liquid, characterized in that a flow rate adjusting valve is provided in the discharge flow path of the scattering cell through which the sample solution flows.