KR20230027855A - Liquid particle couner and liquid particle monitoring system with the same - Google Patents

Abstract

The present invention relates to a liquid particle monitoring system which comprises: one or more liquid particle counters which are respectively connected to one or more liquid supply lines; a spectrum counter which is coupled to the one or more liquid supply lines; one or more connection pipes which respectively connect the spectrum counters and the one or more liquid supply lines and have a valve; and a control unit which is connected to the one or more liquid particle counters to receive a measurement result, and controls the valve. The control unit controls the valve according to the measurement result received from the one or more particle counters.

Description

Liquid particle counter and liquid particle monitoring system having the same {LIQUID PARTICLE COUNER AND LIQUID PARTICLE MONITORING SYSTEM WITH THE SAME}

The present invention relates to a liquid particle monitoring system, and more particularly, to a liquid particle counter and a real-time inline liquid particle monitoring system and method having the same.

Since various liquids used in semiconductors, pharmaceuticals, bio, microelectronics and other industries that require clean room environments, sterilization, and clean production must be used in a state in which appropriate purity is guaranteed, strict management of particulate contaminants in liquids is required. do.

In particular, if the fluid is contaminated with unwanted particles, it can be quickly identified and the process stopped at an early stage to prevent waste due to manufacturing of defective products. Liquid substances, eg detergents, are continuously monitored to ensure proper purity and to ensure that undesirable particles suspended in the fluid are within acceptable tolerances. Particles and impurities in solutions applied in various wet processes (e.g., hydrogen peroxide, photoresist, purifying solutions such as IPA, ammonia, developer and others) affect yield and quality in semiconductor manufacturing.

Meanwhile, even in the case of a polishing agent for chemical mechanical polishing (CMP), it is necessary to monitor the size and number of particles because desired polishing performance can be exhibited only when particles are included at an appropriate level.

Therefore, for solutions used in the process, it is necessary to perform quality control through 24-hour online monitoring of particle size distribution in real time.

Optical Liquid Particle Counters (LPCs) are used in a variety of industries including the semiconductor, pharmaceutical, bio and microelectronics industries. Briefly explaining the action process of the liquid particle counter, when a laser is irradiated to a tube through which liquid flows, the laser is scattered by particles or bubbles in the liquid. The scattering at this time is Rayleigh scattering, and the intensity of the scattered light is measured to measure the size and number of particles. Since LPC uses Rayleigh scattering, it is useful for detecting particles (organic or inorganic) with a size of 30 nm or more. However, in the case of smaller particles of 30 nm or less, there is a problem in that measurement is not possible because the intensity of scattered light is too weak or scattering does not occur. Therefore, in the case of LPC, particles of 4 nm or more and 30 nm or less cannot be detected, and in fact, the purity is judged to be high even though there are more impurities.

In particular, since the line width has reached up to 3 nm in the recent semiconductor field, it is necessary to manage fine impurity particles of 30 nm or less. Furthermore, there is a demand in the field to manage the liquid to have a purity of 10 ³ /cc level in terms of number as well as particle size.

Meanwhile, US Patent No. 6,544,484 and the like discloses a spectral counter for counting finer particles in a liquid by particle size distribution.

Referring to FIG. 1 , the sample solution diluted and mixed in a predetermined ratio by the solution mixing device is subjected to particle monitoring in a spectrum counter (analysis equipment). The spectrum analyzer includes an aerosolization device, a particle size classifier 42, and a CPC 44.

The sample solution is first aerosolized into a plurality of aerosol particles by an aerosolization device. After the aerosol particles are output through the line, they flow into the particle classifier and are classified according to their size before being discharged. For classification, a differential mobility analyzer (DMA) may be used, for example. DMA first ionizes aerosol particles by means of soft X-ray or electric discharge, and then introduces the ionized particles into a passage where an electric field is applied. Incoming ionized particles may be collected in a fractionation channel depending on the applied electric field and particle size. That is, ionized aerosol particles can be collected by size by changing the scan voltage. By this process, aerosol particles can be classified. The sorted vaporized particles are then presented sequentially by size to a Condensation particle counter (CPC), where the selected aerosol particles are passed through a gas stream saturated with butyl alcohol or another volatile liquid, for easy detection. It is condensed into individual particles to an effective size, and the particles grow. U.S. Patent Nos. 4, 790, 650 describe a condensed trace calculator. Grown particles are detected optically by an LPC or other particle counter. By applying the above method, it became possible to detect fine particles of 30 nm or less.

However, this method has a problem in measurement reliability and takes a long measurement time. Figure 2 shows the number of liquid particle sizes measured by the same analyzer as in Figure 1. 2A shows a case where the number of particles in the liquid (1cc) is 10 ⁶ or more, and the distribution of the measured values shows a normal distribution, but in the case of B, where the number of particles is about 10 ⁴ , there are fluctuations in the measured values. You can check. In the case of C, in which the number of particles is less than 10 ³ , the fluctuation of the measured value is very severe, so the reliability of the measured value is low.

Therefore, the smaller the number of impurities, the lower the reliability of the measured value. When the particle concentration is high or significant, the spectrum counter is reliable, but when the particle concentration is low and the impurity concentration is low, the data uniformity is low and the statistical deviation is large, making it difficult to trust the measurement quality. In addition, in order to increase measurement reliability, it takes a lot of time in the classification process to measure several times, and it takes more than 1 hour, and real-time feedback is not available, making it difficult to apply to the process line. Conventionally, this problem could not be solved, and liquid quality was monitored using a sampling concept rather than liquid particle monitoring in real time.

(Patent Document 1) US 6544484 B

To solve the above problems of the present invention, it is intended to provide a device and method for detecting liquid particles in-line in real time.

The present invention is also intended to provide a reliable device and method for high-speed monitoring of particles having a particle size of less than 30 nm in a high-purity liquid.

Another object of the present invention is to provide a particle monitoring system and device having high accuracy while being applied to a process line to actively respond to various particle sizes and concentration ranges of liquid particles.

In order to solve the above problems, the liquid particle counter according to one aspect of the present invention is connected to an aerosolization device that outputs aerosol particles by aerosolizing a liquid and the dryer so that the particles can absorb vapor and grow in size It includes CPC, which condenses so that the particles are condensed and measures the condensed particles by an optical counter.

Preferably, the liquid particle counter further includes a dryer that is connected to the aerosolizer and applies heat to the output flow of the aerosol particles to evaporate liquid and bubbles on the surface of the aerosol particles. The outlet of the dryer is connected to the input of the CPC, and the particles output from the dryer are input to the CPC to be condensed and measured.

A liquid particle monitoring system according to an aspect of the present invention includes one or more liquid particle counters each connected to one or more liquid supply lines, a spectrum counter connected to the one or more liquid supply lines, the spectrum counter and the one or more liquid supply lines. It includes one or more connection tubes each connecting and having a valve, and a controller connected to the one or more liquid particle counters to receive measurement results and control the valves.

Preferably, the controller controls the valve according to measurement results received from the one or more particle counters.

The liquid particle counter includes an aerosolization device that aerosolizes liquid and outputs aerosol particles, and a CPC that condenses the aerosol particles so that they can absorb vapor and grow in size, and measures the condensed particles by an optical counter. do. The spectral particle counter includes an aerosolization device that aerosolizes liquid and outputs aerosol particles, a classifier that classifies the aerosol particles by size, and particles of a predetermined size classified by the classifier can absorb vapor and grow in size. It includes CPC, which condenses so that the particles are condensed and measures the condensed particles by an optical counter.

When the particle concentration as a result of measurement by the at least one liquid particle counter exceeds a predetermined concentration, the control unit opens a valve connected to the corresponding liquid supply line to introduce liquid into the spectral particle counter so that the liquid particle concentration of the corresponding liquid supply line is opened. It is desirable to control to measure .

The liquid particle monitoring method implemented by the liquid particle monitoring system includes: measuring liquid particle concentrations by one or more liquid particle counters respectively connected to one or more liquid supply lines; When a measured value exceeding a predetermined concentration is measured by one of the one or more liquid particle counters, a warning is output and a valve connected to the spectrum counter is opened from the liquid supply line in which the measured value exceeds the predetermined concentration is measured, so that the corresponding liquid introducing liquid from the supply line into the spectrum counter; and measuring the liquid concentration of the corresponding liquid supply line by means of a spectrum counter.

According to another aspect of the present invention, a liquid particle monitoring system includes a first liquid particle counter connected to a liquid supply line, a second liquid particle counter further connected to the liquid supply line, and a controller.

The first liquid particle counter includes an aerosolization device that aerosolizes a liquid and outputs aerosol particles, and a CPC that condenses the aerosol particles so that they can absorb vapor and grow in size, and measures the condensed particles by an optical counter. include

The second liquid particle counter is an optical liquid particle counter that measures the concentration of particles having a predetermined size or more, for example, a particle having a diameter of 30 nm or more, and the first and second liquid particle counters are on the same line of the fluid circuit. Measure the liquid particle concentration.

The controller acquires a particle concentration map of a predetermined size or less based on the concentration map for each particle size measured by the first liquid particle meter and the concentration map for each particle size measured by the second liquid particle meter.

After standardizing the concentration map (T2) for each particle size measured by the second liquid particle meter based on the concentration map (T1) for each particle size measured by the first liquid particle meter, T2' is obtained, and then T2'-T1 By doing so, it is possible to obtain a concentration map of particles with a size of 30 nm or less.

According to another aspect of the present invention, the diameter range of the particle to be measured in the first liquid particle counter is wider than the range of the target particle to be measured in the second liquid particle counter. For example, the second liquid particle counter may measure the concentration of particles having a diameter of 30 nm or more, and the first liquid particle counter may measure the concentration of particles having a diameter of 3 nm or more.

According to one aspect of the present invention, a liquid particle counter capable of reliably measuring the concentration of particles having a size of 4 to 30 nm in a liquid is provided.

According to another aspect of the present invention, a reliable system and method for real-time monitoring of particles having a particle size of less than 30 nm in a high-purity liquid are provided.

According to another aspect of the present invention, particles of various particle sizes and concentrations can be rapidly and accurately monitored in a process line.

1 is a diagram showing a schematic configuration of a spectrum counter.
2 are graphs of liquid particle concentration measured by a spectral counter.
3 is a schematic structural diagram of a liquid particle counter according to an embodiment of the present invention.
4 is a diagram showing the structure of a liquid particle counter according to an embodiment of the present invention.
5 is a diagram showing the structure of a spectrum counter according to an embodiment of the present invention.
6 is a conceptual diagram showing an installation structure of a liquid particle monitoring system according to an embodiment of the present invention.
7 is a flowchart illustrating a particle monitoring method in a liquid particle monitoring system according to an embodiment of the present invention.
FIG. 8 is a diagram showing the relationship between particle concentration graphs for each size measured in the system of FIG. 6 .

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification. In this process, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of explanation.

Throughout the specification, when a part is said to be "connected" to another part, this is not only when it is "directly connected", but also when it is "electrically or communicatively connected" with another element in between. Also includes In addition, when a certain component is said to "include", this means that it may further include other components without excluding other components unless otherwise stated.

As described above, the spectrum counter can measure particles having a small particle size by classifying and collecting them by a classifier, and then increasing the size of the small particles through a condensation process by irradiating light and measuring scattered light. Therefore, even small particles that the conventional LPC could not measure can be measured, but when the particle concentration is low, the spectrum counter has a problem of large statistical deviation.

In order to solve this problem, the inventors of the present invention analyzed the cause of large data deviation and the reason why the spectrum counter takes a long time when the particle concentration is low. The content of the analysis will be specifically described below.

The aerosolized particles in the spectrum analyzer are classified according to their size in the particle classifier, and for classification, the particles are first ionized by soft X-rays. At this time, as a result of the analysis, it was confirmed that the ionization rate was approximately 1% when ionizing particles of 10 nm or less.

When the particle concentration is high, for example, 1 million / cc, 1-2% has representativeness as a sample to some extent, but as the particle concentration decreases, 1-2% becomes less representative as a sample. This is as shown in FIG. 2, and statistical errors become large at low concentrations. Therefore, when the particle concentration is high or significant, the number of particles per unit volume taken for measurement is constant, so the spectrum counter is reliable, but when the particle concentration is low and the impurity concentration is low, the number of particles per unit volume taken for measurement is constant. As a result, data uniformity is low and statistical deviation is large, making it difficult to trust the measurement quality.

Aerosol particles are classified using the fact that charged particles are moved by electromagnetic force through ionization in the following process, and the moving distance and speed vary depending on the particle size. However, if the number of aerosolized particles in the previous step is small, only the particles matching a specific electric field are collected in this classification process, and the rest are discarded, so the representativeness of the sample is insufficient in this process as well.

Summarizing the causes of measurement reliability and time consuming, first, the reliability of the measurement data is very low, as the ionization rate of aerosol particles by soft x-rays is very low, especially around 1% in a small size of 10 nm, and second, the reliability of the ionized particles If the number is not as large as tens of thousands or more, in the sorting process using DMA, except for the particles selected by a specific electric field, the repetition accuracy will be lowered each time the measurement is performed, and thirdly, the particle size ranges from 4 nm to 30 nm with a step of 0.1 nm. It was confirmed that a lot of measurement time was required because scan measurement was performed and several repeated measurements were required due to the low data reliability of one measurement.

The present inventors have devised the liquid particle meter of FIG. 3 in order to solve the cause of this problem and to obtain reliable measurement results even at high purity while being able to detect particles having a diameter of 30 nm or less.

Referring to FIG. 3, the liquid particle counter according to a preferred embodiment of the present invention includes an aerosolizer that outputs aerosol particles by aerosolizing a liquid, and is connected to the aerosolizer to generate heat in the flow of the output aerosol particles. is added to evaporate the liquid on the surface of the aerosol particles, the aerosol particles that do not contain particles, and a dryer to leave only the particles by evaporating the bubbles, and the particles discharged from the dryer are introduced to condense so that the particles can absorb the vapor and grow in size and CPC, which measures the condensed particles by an optical counter. The processing order of the liquid particles is an aerosolizer, a dryer, and a CPC in that order, and the flow of the liquid particles is also movably arranged in this order.

Referring to Figure 4, each component of the present invention will be described in more detail.

The liquid particle counter according to a preferred embodiment of the present invention may be disposed at the branch portion of the liquid supply line, but is not limited thereto. The aerosolization device in the conduit branched from the liquid supply line may be an electrospray, an ultrasonic nebulizer, an atomizer or any drop generator. The liquid flowing into the aerosolization device from an inlet branched from a part of the liquid line or disposed in the middle of the liquid line is discharged by generating aerosol particles by the aerosolization device. The air pressure source required for aerosolization supplies high-pressure air to the liquid pipe through the high-pressure air guiding inlet. The critical gradient ratio resulting from the high-pressure air causes the solution to be converted into aerosol particles.

The outlet of the aerosolization device is connected to the inlet of the dryer so that aerosol particles are introduced into the dryer through the dryer inlet. The dryer is configured so that the aerosol particles pass through a conduit in which a heating element heater is disposed, and excess liquid and bubbles on the surface of the aerosol particles are removed by the heater. Bubbles are generated during the aerosolization process or exist in the original liquid, and in optical counters such as LPC, they scatter light like particles, causing measurement errors. Bubbles are removed by the dryer so that only real particles can be measured.

The dryer may further include an air inlet and a discharge unit on the downstream side of the heating element heater, so that surplus liquid or bubbles may be blown to the discharge unit by air.

The dryer outlet is connected to the input of the CPC, so that aerosol particles dried by the dryer are discharged through the dryer outlet and introduced into a condensation particle counter (CPC) input. The CPC includes a saturated vapor chamber that condenses passing vaporizing particles so that the vaporizing particles can absorb the vapor and a shell layer can be formed, and an optical counter.

Particles of 30 nm or less are also condensed in the CPC and increase in size, so the optical counter can count all particles of various sizes of 4 nm or more.

As such, the liquid particle counter of the present invention goes through aerosolization, drying, condensation, and optical counting processes without a classifier, so it can detect the concentration of liquid particles over a very wide range of size particles, including particles of 30 nm or less. . In addition, liquid particles flowing through the line can be measured within 10 seconds without going through a scan by the classifier. This enables real-time particle monitoring in the process line. In addition, since it does not go through the ionization process, highly reliable measurement data can be obtained.

On the other hand, in the case of a highly volatile liquid such as IPA (isopropyl alcohol), since the surplus liquid on the surface of bubbles or aerosol particles volatilizes after passing through an aerosolization device, it is possible to condense and count particles directly with CPC without a dryer.

Hereinafter, a liquid particle monitoring system and monitoring method according to an embodiment of the present invention will be described with reference to FIGS. 6 and 7 .

Referring to FIG. 6 , the liquid particle monitoring system according to an embodiment of the present invention may be applied to one or more liquid supply lines. Preferably, the liquid particle counter may be connected to each of the plurality of liquid supply lines. The plurality of supply lines may be independent lines or may be different control points on the same fluid circuit.

According to FIG. 6, nano liquid particle counters (NanoCounter1, NanoCounter2, ..., NanoCounter N) are installed branching to N lines or in the middle of the lines, respectively. The spectrum counter (Nano Spectrometer) is connected to the plurality of liquid supply lines by a connection pipe, and each connection pipe is provided with a valve. The system includes a plurality of liquid particle counters, a spectrum counter, and a controller connected to a valve by a cable to receive a measurement result and control the valve.

In addition, this spectrum counter can be configured as a portable device without being connected to a line and can be operated by taking it to a line where a problem occurs and measuring it.

In addition, by arranging LPCs (LPC1, LPC2, ..., LPCN) using Rayleigh scattering in a plurality of lines (Line 1, Line 2, ..., Line N), respectively, the liquid particle counter and the liquid particle count of the same line concentration can be measured. However, in the case of an LPC that irradiates a liquid flowing through a tube with a laser and counts particles using the scattered light, particles larger than 30 nm are detected.

Here, the nano liquid particle counter is the liquid particle counter of FIGS. 3 and 4 described above, and includes an aerosolization device, a dryer, and a CPC, and is a counter that condenses and increases the size of particles of various sizes and counts them by an optical method. . Therefore, it is possible to measure the total number of particles in a short time by covering a wide range of particle sizes.

The spectral particle counter has the structure shown in FIG. 5, and includes an aerosolization device that aerosolizes liquid and outputs aerosol particles, a dryer, a classifier that classifies aerosol particles by size, and particles of a predetermined size classified by the classifier. includes a CPC that absorbs steam, condenses it so that it can grow in size, and measures the condensed particles by an optical counter.

The control unit collects the measurement results of the Nanocounter and the LPC measurement results, determines Ni > Nd (abnormality), generates a line stop alarm when an error occurs, controls the valve of the NanoSpectrometer, and acquires the particle spectrum of the NanoSpectrometer.

6 and 7, the nano liquid particle counters (Nano counter1, Nano counter2, ...Nano counter N, ) installed in each line calculate the liquid particle concentration (pcs/cc) in each line and the calculated particle concentration are collected by each control unit. As a result of the measurement of the N liquid particle counters, the control unit determines that the particle concentration (Ni) of a specific nano-counter exceeds a predetermined concentration (Nd), for example, the measured value of the counter 2 exceeds a predetermined concentration, for example, 5000/cc. In the case (N2 > Nd) valve 2 is opened and the liquid in line 2 flows into the spectrum counter, and the liquid particles are measured by size by the spectrum counter. The classification process by size takes time, but relatively reliable measurements can be obtained when the concentration is high. The predetermined concentration may be appropriately modified according to experimental results.

In this way, the liquid particles in the liquid circuit line are monitored as a whole in real time at a low concentration using the nano liquid particle counter, but when particles of a predetermined concentration or more are detected, additional information can be obtained by measuring the concentration by size using the spectrum counter. In this way, reliable and high-speed particle counting is possible in high-purity liquids, and impurities above a predetermined level can be accurately detected at an early stage, so improved monitoring is possible.

Referring to FIGS. 6 and 8 , a method for mutually complementing measurement results by a nano counter and LPC and obtaining a detection distribution map of liquid particles having a size of 30 nm or less will be described.

According to FIG. 6, the nano counter and the LPC are disposed adjacent to each other on the same liquid circuit line to detect substantially the same liquid particles. The particle concentration measured by the nano counter includes both particles with a diameter of less than 30 nm and particles with a diameter larger than that, but in the case of LPC, only particles with a diameter of 30 nm or more can be detected. 8(a) is the particle concentration measured by the nano counter, and (b) is the concentration measured by LPC. In FIG. 8, the horizontal axis is the particle diameter and the vertical axis is the particle concentration (number/cc).

Therefore, by subtracting the LPC graph (b) from the graph (a) from the nano-counter collected by the control unit, the concentration for each particle size between 4 and 30 nm can be obtained. However, considering the aerosolization rate, it is necessary to go through a process of standardizing the graph (a) from the nano counter to correspond to the graph (b) of the LPC, rather than simple subtraction. After converting the graph (a) as a whole so that the part corresponding to 30 nm or more of the graph (a) matches the graph (b), the concentration for each particle size of 30 nm or less can be obtained by subtracting the graph (b).

Thus, by solving the problem of the spectral particle counter, a liquid particle monitoring system that is reliable and capable of real-time monitoring even when the particle concentration is low can be provided.

Claims (7)

As a liquid particle counter,
an aerosolizing device that aerosolizes a liquid and outputs aerosol particles;
A liquid particle counter including a CPC that condenses the particles so that they can grow in size by absorbing vapor and measures the condensed particles by an optical counter.
According to claim 1,
A dryer connected to an aerosolization device and applying heat to the output flow of the aerosol particles to evaporate liquid and bubbles on the surface of the aerosol particles;
The liquid particle counter, characterized in that the outlet of the dryer is connected to the input of the CPC so that the particles output from the dryer are input to the CPC to be condensed and measured.
As a liquid particle monitoring system,
one or more liquid particle counters each connected to one or more liquid supply lines;
a spectral counter coupled to the one or more liquid supply lines;
at least one connection pipe connecting the spectrum counter and the at least one liquid supply line and having a valve; and
A control unit connected to the one or more liquid particle counters to receive measurement results and control the valve;
The liquid particle monitoring system, characterized in that the control unit controls the valve according to the measurement result received from the one or more particle counters.
According to claim 3,
liquid particle counter,
an aerosolizing device that aerosolizes a liquid and outputs aerosol particles;
A CPC for condensing the aerosol particles so that they can absorb vapor and grow in size and measuring the condensed particles by an optical counter;
The spectral particle counter,
An aerosolizing device that aerosolizes a liquid to output aerosol particles;
A classifier for classifying the aerosol particles by size, and
A liquid particle monitoring system comprising: a CPC for condensing particles of a predetermined size classified by the classifier to absorb steam to grow in size, and measuring the condensed particles with an optical counter.
According to claim 3 or 4,
When the particle concentration as a result of measurement by the at least one liquid particle counter exceeds a predetermined concentration, the control unit opens a valve connected to the corresponding liquid supply line to introduce liquid into the spectral particle counter so that the liquid particle concentration of the corresponding liquid supply line is opened. Liquid particle monitoring system, characterized in that for controlling to measure.
A liquid particle monitoring method performed by the liquid particle monitoring system of claim 3,
measuring the liquid particle concentration by at least one liquid particle counter respectively connected to the at least one liquid supply line;
When a measured value exceeding a predetermined concentration is measured by one of the one or more liquid particle counters, a warning is output and a valve connected to the spectrum counter is opened from the liquid supply line in which the measured value exceeds the predetermined concentration is measured, so that the corresponding liquid introducing liquid from the supply line into the spectrum counter; and
A liquid particle monitoring method comprising the steps of measuring the liquid concentration of a corresponding liquid supply line by means of a spectrum counter.
As a liquid particle monitoring system,
a first liquid particle counter connected to the liquid supply line;
a second liquid particle counter further connected to the liquid supply line; and
including a controller;
The first liquid particle counter includes an aerosolization device that aerosolizes a liquid and outputs aerosol particles, and a CPC that condenses the aerosol particles so that they can absorb vapor and grow in size, and measures the condensed particles by an optical counter. include,
The second liquid particle counter is an optical liquid particle counter and measures the concentration of particles having a predetermined size or more, and the first liquid particle counter measures a target particle size range wider than the target particle size range of the second liquid particle counter. have,
the first and second liquid particle counters measure the liquid particle concentration on the fluid circuit of the same line;
The controller obtains a particle concentration map of a predetermined size or less based on the concentration map for each particle size measured by the first liquid particle meter and the concentration map for each particle size measured by the second liquid particle meter. liquid particle monitoring system.

Images