JP2007327818A - Flow meter and flow method analyzer - Google Patents

Abstract

A flow meter and a flow method analyzer capable of quickly measuring a minute flow rate are provided.
A flow meter (2) is formed of a taper tube (21) having a predetermined taper ratio (a) so as to increase in diameter as it goes upward, a material having a specific gravity and a predetermined diameter (d), and passing through the taper tube (21). And a float 22 that changes the position in the axial direction in the tube in accordance with the flow rate of the sample to be processed. When the specific gravity of the float 22 is 1.5 to 9.0, the diameter d of the float 22 is 0.9 to 3.2 mm, and the taper ratio a of the tapered tube 21 is 0.01 to 0.04. It is possible to measure a minute flow rate using the flow meter 2.
[Selection] Figure 2

Description

  The present invention relates to a flow meter for measuring a flow rate of a sample and a flow method analyzer using the flow meter.

  Various types of flow meters for measuring the flow rate of a sample have been proposed. For example, an area type flow meter using a float, a rotary flow meter using an impeller, a positive displacement flow meter using an ellipse gear, and the like can be given. Among these, an area type flow meter is a simple and inexpensive method.

  This area type flow meter has a float in the taper tube, and flows the liquid from the narrower diameter to the wider one in the taper tube, and detects the flow rate by reading the position of the float from the scale attached to the taper tube. It is. The float stays at a position where the pressure of the liquid flowing in the tube and the weight of the float are in balance, whereby the flow rate of the liquid can be measured.

  Various improvements have been made for such an area type flow meter (see, for example, Patent Document 1). This Patent Document 1 includes a light-transmitting taper tube, a light-shielding float, a light-emitting element and a light-receiving element that are arranged outside the taper tube so as to face each other via the taper tube. An area-type flow meter is disclosed that detects the position of a float that moves in accordance with the flow rate based on the amount of light received by a light receiving element and measures the flow rate of a sample. Specifically, this area-type flow meter has a plurality of light emitting elements that are individually lit along the axial direction of the taper tube and a single light receiving element that faces the light emitting elements. ing. For each light emitting element, the ratio of the light receiving element output signal at the time of flow rate measurement and the light receiving element output signal when the float is excluded from the detection range is detected, and the position of the float is detected based on these multiple ratios. It is configured to do.

Japanese Unexamined Patent Publication No. 1-180419

  Here, the flow rate of the liquid in the flow method analyzer that can analyze the target component in the sample is often very small, but there has not been a flow meter that can measure such a small flow rate. Therefore, when performing the work to adjust the flow rate of the flow method analyzer, the amount of sample liquid discharged from the device within a certain time is measured, and the measurement result is converted into unit time, so that the minute flow rate is reduced. The measurement was substituted. And such substitution measurement was repeated several times until it became a suitable flow volume. Therefore, it takes time to adjust the flow rate of the flow method analyzer a plurality of times, and it is difficult to reduce the number of man-hours for the operator. Moreover, in the flow method analyzer, the liquid feed pump is controlled so as to have a predetermined flow rate, but it has been difficult to confirm that the actual flow is as controlled.

The present invention has been made to solve the technical problems as described above, and an object thereof is to provide a structure capable of quickly measuring a minute flow rate.
Another object is to provide a structure that can quickly measure a minute flow rate and can handle a larger flow rate.

For this purpose, the flowmeter to which the present invention is applied includes a tapered tube formed with a predetermined taper ratio so that the diameter of the tube through which the sample for measuring the flow passes increases toward the downstream side of the tube, and a taper. A float that is accommodated in the tube and changes an axial position in the tube according to a flow rate of the sample passing through the taper tube, and the taper tube has a predetermined taper ratio of 0.01 to 0.04, The float has a specific gravity of 1.5 to 9.0, and the float has a diameter of 0.9 to 3.2 mm.
The taper tube may be characterized by having a bulge portion that expands at a taper ratio larger than a predetermined taper ratio on a downstream side of a portion that expands at a predetermined taper ratio.

  From another point of view, the flow method analyzer to which the present invention is applied is a flow method analyzer that analyzes a target component in a sample, and the diameter of the flow method analyzer increases as it goes downstream in the tube through which the sample passes. A taper tube formed at a predetermined taper ratio, and a float that is accommodated in the taper tube and changes an axial position in the tube according to a flow rate of the sample passing through the taper tube. The predetermined taper ratio is 0.01 to 0.04, the specific gravity of the float is 1.5 to 9.0, and the diameter of the float is 0.9 to 3.2 mm. . Examples of the flow method analyzer described here include an FIA (flow injection analysis) device, an inverse FIA device, an ion chromatograph device, and a liquid chromatograph device.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the structure which can measure a micro flow rate rapidly.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Here, as a method for simply measuring the components of the sample solution, a detector provided downstream after introducing the sample solution or the reagent solution into the reagent solution or the sample solution flowing in the narrow tube and performing the reaction operation, etc. A FIA method for detecting a target component is known. This FIA method detects a reaction result by causing a chemical reaction to be performed while controlling mixing of a reagent and a sample in a laminar flow in a thin tube without using a reaction vessel such as a beaker or a flask. It is. Of these FIA methods, the one that injects the reagent solution into the continuous flow system of the sample solution is called reverse FIA and can reduce the consumption of the reagent. Is suitable.

FIG. 1 is a schematic configuration diagram of a flow method analyzer 1 according to the present embodiment.
As shown in FIG. 1, a pump 12 such as a peristaltic pump or a plunger pump is interposed in a tubular main channel 11 through which a sample solution flows as a sample feeding means. The suction end of the pump 12 is inserted into the sample liquid tank 13. Further, the discharge-side tip of the syringe pump 14 that constitutes the reagent solution injecting means joins the main flow path 11 at the joining position 15. The suction end of the syringe pump 14 is inserted into the reagent liquid tank 16. Further, a detector 17 for detecting a reaction between the sample solution and the reagent solution is provided on the downstream side of the joining position 15 of the main channel 11. A flow meter 2 is disposed downstream of the detector 17.

  A switching valve such as a slide valve or a check valve is appropriately used so that the reagent liquid is sucked from the reagent liquid tank 16 side when the syringe pump 14 is sucked and the reagent liquid is discharged toward the merging position 15 at the time of discharge. The liquid feeding direction is controlled. In addition, the syringe pump 14 sucks a batch of reagent solution from the reagent solution tank 16 at a time, and then sequentially discharges the reagent solution for each amount necessary for one injection using a stepping motor or the like. It has become. When all the reagent solutions inside are discharged, the operation from the suction is repeated again.

  In this analyzer, the pump 12 is operated to continuously flow the sample liquid into the main channel 11. Then, the syringe pump 14 is operated to discharge the reagent solution and join the sample solution. Then, the reagent solution merged in the main channel 11 reacts while being diffusely mixed with the surrounding sample solution. And the target component in a sample liquid can be analyzed by detecting this reaction product with the detector 17. FIG.

FIG. 2 is a schematic configuration diagram of the flow meter 2 of the flow method analyzer 1.
A flow meter 2 shown in FIG. 2 includes a tapered tube (measuring tube, microtapered tube) 21 formed with a predetermined taper ratio a so as to increase in diameter toward the downstream side (upward) of the flow path, A float (floating element, movable part) 22 that changes the position in the axial direction in the tube according to the flow rate of the sample that is accommodated in the tube and passes through the tapered tube 21 is provided. More specifically, in the flowmeter 2, a float 22 having a diameter d that can be freely moved up and down is accommodated in a taper tube 21 having an upwardly inclined taper ratio a, and the taper tube 21 is assembled with an appropriate support (not shown). It is a type flow meter.
When the eluent (fluid) containing the sample liquid is caused to flow from the lower side to the upper side of the flow meter 2 configured as described above, the float 22 is pushed up due to the force due to the pressure difference generated before and after that. As the float 22, for example, fine ceramic beads can be adopted.

Here, as the float 22 moves upward, the flow area between the float 22 and the tapered tube 21 increases. Therefore, when the float 22 moves upward, the velocity of the fluid passing therethrough decreases and the pressure difference decreases. That is, the float 22 stops at a height h where the mass (specific gravity γ) of the float 22 and the force due to the pressure difference are balanced. At this time, the flow area determined by the height h of the float 22 in the tapered tube 21 and the flow rate (volume flow rate) Q of the fluid passing therethrough are in a fixed relationship. Therefore, the flow rate Q of the sample liquid can be measured by detecting the height h of the float 22 in the tapered tube 21.
The relationship between the taper ratio a of the tapered tube 21, the diameter d of the float 22, the specific gravity γ of the float 22, the height h of the float 22, and the flow rate Q will be described later.

FIG. 3 is a view for explaining the tapered tube 21 of the flow meter 2.
As shown in FIG. 3, the tapered tube 21 has a main body 21 a in which the inside of the tube is formed with a predetermined taper ratio a, and extends upward from the upper end of the main body 21 a, and the diameter thereof is increased with a taper ratio larger than the taper ratio a. A stepped portion (swelled portion) 21b formed in such a manner and a large diameter portion 21c extending further upward from the upper end of the stepped portion 21b are provided. Such a stepped portion 21b and a large diameter portion 21c increase the flow rate range of the tapered tube 21.
The taper ratio a is determined from the diameter φe of the upper end of the main body 21a, the diameter φf of the main body 21a at the portion where the float bottom is located when the float 22 is at the lowest position, and the length s between them. Can be derived. That is, it is calculated by the taper ratio a = (e−f) / s.

FIG. 4 is a table showing the relationship among the taper ratio a, the diameter d (mm), the specific gravity γ, the height h (mm) of the float 22 and the flow rate Q (ml / min).
As shown in FIG. 4, the specific gravity γ of the float 22 is in the range of 1.5 to 9.0, the diameter d of the float 22 is in the range of 0.9 to 3.2 mm, and the tapered tube 21. When the taper ratio a of the main body 21a is in the range of 0.01 to 0.04, a minute flow rate can be measured.

For example, when the specific gravity γ is 1.5, the diameter d is 3.2 mm, and the taper ratio a is 0.01, when the height h of the float 22 is 10 mm, the height is 9.7 ml and the height h is 20 mm. 10.5 ml per minute, 11.4 ml per minute when the height h is 30 mm, and 13.2 ml per minute when the height h is 50 mm.
For example, when the specific gravity γ is 9, the diameter d is 0.9 mm, and the taper ratio a is 0.01, when the height h of the float 22 is 10 mm, 0.26 ml per minute and the height h is 20 mm. Sometimes 0.83 ml / min, 1.44 ml / min when the height h is 30 mm, and 2.83 ml / min when the height h is 50 mm. As described above, when the above three conditions are satisfied, a minute flow rate can be measured. Here, the minute flow rate means a flow rate within a range of 0 to 5 ml per minute.

Of the three conditions described above, the specific gravity γ is preferably in the range of 3.0 to 7.0, the diameter d is in the range of 1.0 to 2.0 mm, and the taper ratio a is more preferable. Is in the range of 0.01 to 0.03.
For example, when the specific gravity γ is 3, the diameter d is 1 mm, and the taper ratio a is 0.03, 1 mm / min when the height h of the float 22 is 10 mm, and 2 min / min when the height h is 20 mm. When the height h is 30 mm, it is 3.7 ml per minute. When the height h is 50 mm, it is 7.4 ml per minute.

Of the three conditions described above, the specific gravity γ is preferably in the range of 5.0 to 6.5, the diameter d is in the range of 1.0 to 1.4 mm, and the taper ratio a Is in the range of 0.01 to 0.025.
For example, when the specific gravity γ is 6.5, the diameter d is 1 mm, and the taper ratio a is 0.01, when the height h of the float 22 is 10 mm, 0.5 ml per minute, and when the height h is 20 mm 1 ml per minute, 1.6 ml per minute when the height h is 30 mm, and 2.9 ml per minute when the height h is 50 mm. Thus, if the flow rate near 1 ml per minute can be easily measured by the flow meter 2, the flow method analyzer 1 can improve the workability of the flow rate adjustment.

FIG. 5 is a graph showing the result of calculation according to a theoretical formula under predetermined conditions. The vertical axis represents the height h (mm) of the float 22 and the horizontal axis represents the flow rate (ml / min). The predetermined condition here refers to a case where the specific gravity γ is 8.8, the diameter d is 1.10, and the taper ratio a is 0.02.
FIG. 6 is a graph showing the results of an actual experiment compared with the theoretical formula shown in FIG. 5. The vertical axis is the height h (mm) of the float 22, and the horizontal axis is the flow rate (ml / min). It is. The prototype 1 in FIG. 6 has a specific gravity γ of 6, a diameter d of 1.10, and a taper ratio a of 0.02. In the trial production 2, the specific gravity γ is 6, the diameter d is 1.15, and the taper ratio a is 0.02. As shown in FIG. 6, when the prototype 1, the prototype 2, and the theoretical formula are compared, the theoretical formula and the experimental data of the prototype are slightly dissociated, but the relationship between the height and the flow rate can be obtained by the approximate formula.

FIG. 7 is a schematic configuration diagram of an ion chromatograph apparatus 3 that is an example of the flow method analyzer 1 according to the present embodiment.
Here, the ion chromatograph apparatus 3 shown in FIG. 7 is for measuring the concentration of ions in the sample solution, and the target ions in the sample are separated by using an ion analysis column to separate the target ions. It is for analysis. The ion chromatograph is a kind of high-performance liquid chromatograph and is used in various fields such as wastewater management and environmental measurement as an analyzer for separating and measuring ion components in an aqueous solution. .

  The configuration of the ion chromatograph apparatus 3 will be described. As shown in FIG. 7, the ion chromatograph apparatus 3 includes a deaerator 31, a liquid feed pump 32, a pressure sensor 33, an injector 34, a column 35, a detector 36, and data. It comprises a processing device 41, a display 42 and a printer 43. The column 35 and the detector 36 are housed in a thermostatic chamber 37 for keeping the measurement temperature constant.

The eluent passes through a deaeration device 31 for removing a gaseous component, and is sent to an injector 34 through a pressure sensor 33 by a liquid feed pump 32. When the sample liquid to be measured is injected into the injector 34, it is sent to the column 35 by the eluent, the ion component is separated by the column 35, reaches the detector 36, and is detected as a change in electrical conductivity. The data processing device 41 performs data processing based on the detection result by the detector 36, and the result is displayed on the display device 42 and printed by the printer 43 as necessary.
The eluent containing the sample liquid exits the detector 36 and is discharged through the flow meter 2.

  Here, an electric conductivity detector is generally used as the detector 36. However, since the eluent of the ion chromatograph has high electric conductivity, a device called a suppressor for reducing the background may be used in combination. is there. As for the sensitivity of the ion chromatograph, in the case of a general loop (volume; several tens of μl) injection method, ion components of several tens of ppb level can be quantified.

FIG. 8 is a graph showing a chromatogram, in which the vertical axis represents the change in electrical conductivity and the horizontal axis represents the elution time.
In the ion chromatograph apparatus 3, the change in electrical conductivity due to the sample solution is represented as a chromatogram as shown in FIG. In the data processing device 41 (see FIG. 7), for each peak of the chromatogram, the ion species is calculated from the elution time (for example, t), and the concentration of the ion is calculated from the peak area (for example, the shaded portion S). .

  In the flow method analyzer 1, it is necessary to adjust the flow rate of the sample liquid (eluent) in advance. For this reason, an apparatus equipped with a flow meter 2 improves the workability of flow rate adjustment, and it is easy to visually check that the sample liquid (eluent) is flowing normally during operation of the apparatus. can do.

It is a schematic block diagram of the flow system analyzer which concerns on this Embodiment. It is a schematic block diagram of the flowmeter of a flow system analyzer. It is a figure for demonstrating the upper part of the taper tube of a flowmeter. It is a table | surface which shows the relationship between a taper ratio, a diameter, specific gravity, the height of a float, and a flow volume. It is a graph which shows the result calculated by the theoretical formula. It is a graph which shows the result of actually experimenting compared with a theoretical formula. It is a schematic block diagram of the ion chromatograph apparatus which is an example of the flow system analyzer which concerns on this Embodiment. It is a graph which shows a chromatogram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Flow system analyzer, 2 ... Flowmeter, 21 ... Tapered tube, 21a ... Main body, 21b ... Step part, 21c ... Large diameter part, 22 ... Float

Claims (4)

A taper tube formed at a predetermined taper ratio so that the diameter of the tube through which the sample for measuring the flow rate passes increases downstream.
A float that is housed in the taper tube and changes an axial position in the tube according to a flow rate of the sample passing through the taper tube;
Including
The taper tube has a predetermined taper ratio of 0.01 to 0.04, a specific gravity of the float of 1.5 to 9.0, and a diameter of the float of 0.9 to 3.2 mm. Characteristic flow meter.   2. The flowmeter according to claim 1, wherein the taper pipe has a bulging portion whose diameter is increased at a taper ratio larger than the predetermined taper ratio on a downstream side of a portion whose diameter is increased at the predetermined taper ratio. . A flow method analyzer for analyzing a target component in a sample,
A taper tube formed with a predetermined taper ratio so that the diameter of the tube through which the sample passes is increased toward the downstream side of the tube;
A float that is accommodated in a tube of the tapered tube and changes an axial position in the tube in accordance with a flow rate of a sample passing through the tapered tube;
Including
The taper tube has a predetermined taper ratio of 0.01 to 0.04, a specific gravity of the float of 1.5 to 9.0, and a diameter of the float of 0.9 to 3.2 mm. Characteristic flow method analyzer.   The flow system according to claim 3, wherein the tapered pipe has a bulging portion whose diameter is increased at a taper ratio larger than the predetermined taper ratio on a downstream side of the portion whose diameter is increased at the predetermined taper ratio. Analysis equipment.

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