JP2006292390A - Dilution device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dilution device having a simple structure, capable of acquiring a diluted gas easily and highly accurately without requiring a skilled work. <P>SOLUTION: This dilution device for mixing a dilution object gas with a diluting gas at a prescribed flow ratio by a flow ratio mixing method is equipped with the first space wherein a sample gas GA as the dilution object gas is filled beforehand; a space 1' in a container as the second space to which the diluting gas GB is supplied; a collection bag 2 for separating the first and second spaces, used as a partition wall deformable by a pressure; the first fluid resistance part 5 whose inlet side is communicated with the inside of the collection bag 2, and whose outlet side is communicated with a pipe 7 for diluted gas discharge; and the second fluid resistance part 6 whose inlet side is communicated with the space 1' in the container, and whose outlet side is communicated with the pipe 7. Each pressure inside and outside the collection bag 2 is equalized by deformation of the collection bag 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a diluting device for diluting a gas at a desired dilution rate.

For example, it is impossible to measure a sample having a concentration of 180 ppm using an analyzer having a measurable range (maximum scale value) of 100 ppm. In that case, is an analyzer having a larger measurable range used? The sample needs to be diluted so that its concentration falls within the measurable range of the original analyzer.
As is well known, dilution refers to reducing the concentration of a target substance by mixing a substance containing the target component with a substance not containing the target component. In the above example, a sample having a concentration of 180 ppm is 1 When diluted to / 2, it becomes 90 ppm and falls within the measurable range of the analyzer, so that it can be measured using this analyzer.

  In addition to the above-described analysis operation, for example, when calibrating a nitrogen oxide measuring device for environmental air, there is no low-concentration standard gas in the vicinity of the environmental standard 40-60 ppb necessary for calibration. Nitrogen monoxide (NO) standard gas with traceability secured by jcss (measurement method calibration company certification system) is diluted with zero-adjusted standard gas (zero gas) by gas preparation device, and calibration of ppb concentration Standard gas is prepared.

  Here, as a gas dilution method, in addition to the mass ratio mixing method and the volume ratio mixing method (both refer to JIS K0055: General Rules for Gas Analyzer Calibration Methods), the target of dilution is a flow rate ratio corresponding to the desired dilution rate. A flow ratio mixing method for mixing a gas and a diluting gas is known, and examples of the diluting device include a mass flow diluting device and a capillary diluting device. Hereinafter, these configurations will be described.

FIG. 3 is a configuration diagram of a mass flow type diluting device, in which 21 is a cylinder containing NO standard gas as dilution target gas, 22 is a cylinder containing zero gas as dilution gas, 23 and 24 are pressure reducing valves, 25 and 26 are pressure gauges, 27 and 28 are mass flow controllers, and 41 and 42 are pipes.
In this mass flow type diluting device, the flow rate ratio (that is, dilution ratio) of NO standard gas and zero gas is controlled to a predetermined value by two mass flow controllers 27 and 28 and mixed, thereby calibrating the target ppb concentration. Prepare NO standard gas.

FIG. 4 is a block diagram of a capillary type diluting device, in which capillaries 29 and 30 are arranged instead of the mass flow controllers 27 and 28 in FIG.
This capillary type diluter mixes and dilutes a gas having a flow rate corresponding to the fluid resistance of each capillary 29, 30, and adjusts the pressure reducing valves 23, 24 to adjust the pressure on the upstream side of the capillaries 29, 30. By making them equal, the pressure differences between the upstream and downstream of the capillaries 29 and 30 are made equal to keep the flow rate ratio between the NO standard gas and the zero gas constant.
In some cases, an orifice or a nozzle is used instead of the capillary as means for realizing the fluid resistance.

On the other hand, when sample gas such as exhaust gas in a painting process of an automobile or the like is collected and analyzed in an analysis room at a different location, a collection bag made of a fluororesin or the like may be used. At that time, if the concentration of the target component in the collected sample gas is higher than the measurable range of the analyzer, it is necessary to replace the analyzer with a higher range analyzer or dilute the sample gas.
As a dilution method at this time, a portion of the sample gas is collected from the collection bag by a syringe and injected into another collection bag, and the sample gas is further diluted by injecting high-purity air. .

  As described above, various gas diluting methods are known. However, in the calibration gas regulator shown in FIGS. 3 and 4, the cylinders 21 and 22 containing the standard gas are heavy and inconvenient to carry. Further, if the zero preparation gas is replaced by a zero gas purifier, one cylinder 22 is not necessary, but a device is required to completely eliminate the target component standard gas, which causes a problem in terms of dilution accuracy.

Furthermore, the collection bag can be applied to dilute the calibration gas, but when using the collection bag to dilute the sample gas or calibration gas, it is proficient in the operation of the syringe and dispensing. In addition, since so-called co-washing is difficult, there is a problem that it is easily affected by the environmental air in which dilution work is performed.
In addition, there is a disadvantage that the dilution accuracy decreases if there is a residual gas when the collected sample gas is injected into another collection bag.

  Various sampling devices using a collection bag are provided, including Patent Documents 1 to 3. These conventional techniques store a collection bag in an airtight container, increase or decrease the pressure inside the container, and act on the outer surface of the collection bag to collect a sample in the collection bag or collect the collection bag. The sample inside is supplied to the analyzer, but there is no disclosure about the dilution operation of the sample gas or the calibration gas.

Japanese Utility Model Publication No. 50-109692 (FIG. 1) Japanese Utility Model Publication No. 52-48477 (FIG. 2) Japanese Utility Model Publication No. 52-114084 (FIGS. 1 and 2)

As described above, the conventional technology has a problem that the sample gas and the calibration gas collected using the collection bag cannot be diluted easily and with high accuracy.
SUMMARY OF THE INVENTION An object of the present invention is to provide a diluting apparatus having a simple configuration that can easily obtain a diluting gas with high accuracy without requiring a skilled work in a diluting apparatus based on a flow ratio mixing method.

In order to solve the above-mentioned problem, the invention described in claim 1 is a dilution apparatus that mixes a dilution target gas and a dilution gas at a predetermined flow rate ratio by a flow rate mixing method.
A first space prefilled with a gas to be diluted;
A sealed second space to which dilution gas is supplied;
A partition wall separating the first and second spaces and deformable by pressure;
A first fluid resistance portion in which the inlet side communicates with the first space, and the outlet side communicates with the dilution gas discharge pipe;
A second fluid resistance portion that communicates with the second space on the inlet side and on the outlet side with the dilution gas discharge pipe;
By the deformation of the partition, the pressure in the first space and the pressure in the second space are made equal.

The invention described in claim 2 is the invention according to claim 1,
The partition is formed by a collection bag made of a stretchable material.

The invention described in claim 3 is the invention according to claim 1 or 2,
A valve is disposed in the dilution gas discharge pipe.

The invention described in claim 4 is, in claim 3,
Another valve is arranged in a pipe branched from the inlet side or the outlet side of the valve.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a valve is disposed on the inlet side of the first fluid resistance portion.
According to a sixth aspect of the present invention, in any one of the first to fifth aspects, a third fluid resistance portion communicating with the second space is arranged.

In the present invention, the collection bag filled with the gas to be diluted is accommodated in a sealed container, thereby forming the first and second spaces using the collection bag as a partition. Further, the inlet sides of the first and second fluid resistance portions made of capillaries or the like are communicated with the first and second spaces, respectively, and the outlet sides thereof are merged.
As a result, the collection bag is deformed so that the pressures in the first and second spaces are equal, and the pressure difference between the inlet and outlet of the first and second fluid resistance units is equalized. The dilution gas flows out at a constant flow rate ratio and merges in the dilution gas discharge pipe, and the dilution target gas is diluted at a dilution rate corresponding to the flow rate ratio.
According to the present invention, it is possible to generate a gas having a desired dilution rate with high accuracy without performing a complicated operation such as collecting and dispensing a gas to be diluted with a syringe as in the past, or an operation requiring skill. In addition, the structure is simple and can be provided at low cost.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes a sealed container, in which a collection bag 2 preliminarily filled with a sample gas GA as a dilution target gas is stored. Reference numeral 3 denotes a pipe to which a dilution gas GB such as zero gas for diluting the sample gas GA is supplied. It communicates with a space (hereinafter referred to as a container internal space 1 ').
Here, the internal space of the collection bag 2 constitutes the first space in the claims, the in-container space 1 'constitutes the second space, and the collection bag 2 constitutes the partition wall.

A pipe 4 is connected to the collection bag 2, and the pipe 4 passes through the sealed container 1 and communicates with the first first fluid resistance portion 5. The outlet side of the fluid resistance portion 5 communicates with a pipe 7 serving as a dilution gas discharge pipe.
On the other hand, the pipe 3 after the branching of the pipe 3 a communicates with the second fluid resistance portion 6, and the outlet side of the fluid resistance portion 6 communicates with the pipe 7.
The collection bag 2 is formed of a stretchable and easily deformable material such as fluororesin represented by tetrafluoroethylene, and the first and second fluid resistance portions 5 and 6 are capillaries. , An orifice or a nozzle.

Next, a method of using this embodiment will be described.
First, the collection bag 2 from which the sample gas GA is collected is housed in the sealed container 1, and then the dilution gas GB is supplied from the inlet of the pipe 3 at a pressure higher than the ambient pressure. The pressure P ₂ of the diluent gas GB, together applied to the inlet of the second fluid resistance portion 6, also applied to the container interior space 1 'via the pipe 3a.
Since the collection bag 2 is made of a thin and easily deformable material, the collection bag 2 is deformed according to the pressure of the sample gas GA and the pressure in the container space 1 ′, and is stable in a state where both pressures are balanced. To do. Accordingly, in a stable state, the pressure of the sample gas GA is equal to the pressure of the internal space 1 ′, and the pressure P _{1 at} the inlet of the first fluid resistance unit 5 connected from the collection bag 2 via the pipe 4. Becomes equal to the pressure in the inner space 1 ′, that is, the pressure P _{2 at} the inlet of the second fluid resistance portion 6.

That is, the pressures P ₁ and P _{2 at} the inlets of the first and second fluid resistance units 5 and 6 are equal (P ₁ = P ₂ ), and the pressures at these outlets are also kept equal by the common pipe 7. Therefore, since the pressure difference between the inlets and outlets of the first and second fluid resistance parts 5 and 6 is equal, the sample gas GA and the dilution gas GB are set at a constant flow ratio set by the fluid resistance parts 5 and 6. These gases join and mix through the pipe 7. As a result, the sample gas GA is diluted at a dilution rate corresponding to the flow rate ratio.

Note that when the sample gas GA of a specified capacity or more is put into the collection bag 2, the pressure increases and P ₁ > P ₂ , so the flow rate ratio may not be constant, but the collection bag 2 is sealed. It is possible to determine to some extent whether the internal pressure is excessive or insufficient by visually observing the appearance of the collection bag 2 before storing it in the container 1.
Further, since the collection bag 2 has a slight deformation resistance, the pressure of the dilution gas GB needs to be a value sufficiently larger than the deformation resistance. However, when the gas flow rate discharged from the collection bag 2 through the first fluid resistance portion 5 is small, the deformation resistance of the collection bag 2 can be ignored.

Next, FIG. 2 shows a specific configuration of a dilution apparatus that actually dilutes the sample gas based on the configuration of FIG.
When the concentration of the sample gas GA collected by the collection bag 2 is larger than the measurement range of the analyzer (not shown), the collection bag 2 is accommodated in the sealed container 1 as described above, and the dilution gas GB is stored. The sample gas diluted at a desired dilution rate (hereinafter referred to as dilution gas) can be flowed out from the pipe 7. A separate collection bag 11 may be attached to the outlet of the pipe 7, and a predetermined amount of diluted gas may be collected and used for analysis.

In this case, if there is only the pipe 7 between the fluid resistance portions 5 and 6 and the collection bag 11, the collection bag 11 may burst, so the supply amount to the collection bag 11 exceeds a predetermined value. It is desirable to provide a relief function (relief valve).
For example, as shown in FIG. 2A, a stop valve 10 that closes when a predetermined amount of dilution gas is supplied to the collection bag 11 is arranged in the pipe 7, or the pipe 7a is branched to collect the collection bag. 11 may be provided with an overflow valve 9 that opens after a predetermined time has passed since the dilution gas was supplied. Further, the purge valve 8 may be arranged by branching the pipe 4a from the pipe 4 communicating with the original collection bag 2 so that the residual gas in the pipe 4 can be purged in a short time.
Further, as shown in FIG. 2 (b), the third fluid resistance portion 12 is arranged in the sealed container 1 to communicate with the container inner space 1 ′, thereby creating a gentle flow in the pipe 3a. By preventing the backflow of this part, the contamination of the zero gas flowing in the fluid resistance unit 6 may be eliminated.

In the above embodiment, not only the sample gas supplied to the analyzer is diluted but also the collection bag 2 is filled with the calibration standard gas as the dilution target gas and generated as the dilution gas GB by the zero gas purifier. By supplying zero gas, a calibration gas having a desired concentration can be easily prepared.
In addition, the present invention is based on obtaining the desired dilution rate by equalizing the pressure of the dilution target gas and the dilution gas through the first and second fluid resistance portions, The structure of the collection bag is not limited to that shown in FIGS. 1 and 2. For example, any structure may be used as long as the dilution target gas and the dilution gas coexist through a deformable partition wall.

It is a schematic block diagram which shows embodiment of this invention. It is a specific block diagram of embodiment of FIG. It is a block diagram of a mass flow type dilution apparatus. It is a block diagram of a capillary type dilution apparatus.

Explanation of symbols

1: Sealed container 1 ': Space inside container 2, 11: Collection bag 3, 3a, 4, 4a, 7, 7a: Piping 5, 6, 12: Fluid resistance part 8: Purge valve 9: Overflow valve 10: Stop valve

Claims (6)

In a diluting device that mixes a gas to be diluted and a gas for dilution at a predetermined flow rate ratio by a flow rate mixing method,
A first space prefilled with a gas to be diluted;
A sealed second space to which dilution gas is supplied;
A partition wall separating the first and second spaces and deformable by pressure;
A first fluid resistance portion in which the inlet side communicates with the first space, and the outlet side communicates with the dilution gas discharge pipe;
A second fluid resistance portion that communicates with the second space on the inlet side and on the outlet side with the dilution gas discharge pipe;
A dilution apparatus characterized in that the pressure in the first space and the pressure in the second space are made equal by the deformation of the partition wall. The dilution device according to claim 1,
A diluting apparatus, wherein the partition wall is formed by a collection bag made of a stretchable material. The dilution apparatus according to claim 1 or 2,
A diluting apparatus, wherein a valve is arranged in the diluting gas discharge pipe. The dilution apparatus according to claim 3, wherein
A diluting device, wherein another valve is arranged in a pipe branched from the inlet side or the outlet side of the valve. In the dilution apparatus according to any one of claims 1 to 4,
A diluting device, wherein a valve is disposed on an inlet side of the first fluid resistance portion. In the dilution device according to any one of claims 1 to 5,
A dilution apparatus comprising a third fluid resistance portion communicating with the second space.

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