JPH0321470Y2 - - Google Patents

Description

[Detailed description of the invention] In the present invention, a diffusion tube whose internal sample diffusion path communicates with the inside of the liquid reservoir sealed container is connected to the liquid reservoir sealed container, and the vapor of the sample liquid in the liquid reservoir sealed container is transferred to the liquid reservoir sealed container. Regarding a standard gas production device that diffuses through a diffusion path of a diffusion tube and then flows out to the outside and mixes the outflow vapor with dilution gas to obtain a standard gas, in more detail, a membrane having gas permeability is used. The present invention relates to an apparatus for producing a standard gas that can stably obtain a standard gas at a ppb to ppm level by using the above, and is easy to handle.

BACKGROUND ART Conventionally, as a method of obtaining a standard gas by utilizing gas diffusion or osmosis, a method using a standard gas generating device such as a permeation tube or a diffusion tube has been known.

The method using a permeation tube involves sealing the sample liquid in a permeation tube such as a tetrafluoroethylene resin tube, and allowing the sample to permeate and diffuse into the permeation tube. This is a method to obtain a standard gas of a predetermined concentration by utilizing the fact that the amount of gas that diffuses from the outer wall after heating remains constant depending on the temperature. However, although permeation tubes are easy to handle, they take time to become stable after use because they utilize an osmotic phenomenon, and this method is limited to ppb to several ppb.
It is suitable for obtaining standard samples with concentrations on the ppm level, but not suitable for obtaining standard samples with concentrations on the ppm level.

In addition, in the method using a diffusion tube, the vapor of the sample liquid in the liquid reservoir is diffused through the sample diffusion path in the diffusion tube and then flows out to the outside. This method utilizes the fact that the speed of diffusion in a diffusion tube with a constant inner diameter is constant, and the vapor pressure of the liquid is 5 to 400 mm.
If the diluent gas flow rate is 2/min or less in the Hg range, it can be used and a ppm level standard gas can be obtained. However, because the vapor and liquid phases in the diffusion tube are in direct contact, changes in the liquid level may affect the diffusion tube, and if excess sample adheres to the inner wall of the diffusion tube or the liquid reservoir, stable vapor flow may occur. Therefore, it is necessary to prevent the liquid from adhering to the inner wall of the diffusion tube or liquid reservoir when replenishing the liquid or weighing it, and it is also necessary to leave it stationary before use.
In addition to being troublesome to handle, there are problems in that the amount of standard gas generated cannot be reduced very much.

The present invention was developed in view of the above circumstances, and includes a liquid reservoir sealed container into which a sample liquid is placed, and a diffusion passage connected to the liquid reservoir sealed container, with an internal sample diffusion path communicating with the inside of the liquid reservoir sealed container. In the standard gas production apparatus, the vapor of the sample liquid in the liquid reservoir airtight container diffuses through the sample diffusion path of the diffusion tube and then flows out. A liquid reservoir chamber is formed in the liquid reservoir sealed container by partitioning it with a membrane through which the vapor of the sample liquid can pass, and after the vapor of the sample liquid placed in this liquid reservoir chamber passes through the membrane, it is removed from the sample in the diffusion tube. By making the diffusion path diffuse, ppb~
The purpose of the present invention is to provide a standard gas generation device that can stably obtain a standard gas with a wide range of concentrations such as the ppm level, is not affected by changes in liquid level, and is easy to handle.

Hereinafter, one embodiment of the present invention will be described in more detail with reference to the drawings.

In Fig. 1, reference numeral 1 indicates a standard gas generation device according to an embodiment of the present invention. It has a cylindrical glass diffusion tube 4 which is protruded from the upper wall of the container 2 and has a sample diffusion path 3 formed inside that communicates with the inside of the liquid reservoir sealed container 2 . A membrane 5, which does not allow the sample liquid to pass through but allows the vapor of the sample liquid to pass through, is horizontally stretched approximately in the center of the liquid reservoir sealed container 2. A liquid reservoir chamber 6 is formed below the membrane 5 by partitioning the inside of the chamber 2 in a liquid-tight manner. Further, a sample liquid inlet 7 is bored in the side wall of the liquid reservoir closed container 2 slightly below the membrane 5 arrangement position, and a stopper 8 is inserted into this sample liquid inlet 7.

When using the standard gas generation device 1 described above, first, a sample liquid is injected from the sample liquid injection port 7 into the liquid storage chamber 6 in the liquid storage sealed container 2, and then the stopper 8 is inserted into the sample liquid injection port 7. Next, this standard gas generation device 1 is placed in a standard gas production mechanism such as a constant temperature holder, and after the vapor of the sample liquid 9 in the liquid storage chamber 6 passes through the membrane 5, this vapor is transferred to the sample in the diffusion tube 4. The gas is diffused into the diffusion path 3 and flows out of the diffusion tube 4, and then diluted with a diluent gas to obtain a standard gas.

In the above-mentioned standard sample manufacturing apparatus 1, a liquid-tight liquid storage chamber 6 is formed by partitioning the inside of the liquid storage sealed container 2 with a membrane 5 through which the vapor of the sample liquid can pass, and the sample liquid 9 in this liquid storage chamber 6 is After the vapor passes through the membrane 5, it is diffused through the sample diffusion path 3 in the diffusion tube 4, so that the sample liquid 9 and the diluent gas do not come into direct contact with each other, and the thickness of the membrane 5,
ppb ~ by adjusting pore size, surface area, etc.
Standard gases having various concentrations on the order of ppm can be obtained, and the fixedly arranged membrane 5 acts like a liquid surface.
Since the sample vapor is in a state of diffusion, it is not affected by changes in the liquid level and a standard gas of a predetermined concentration can be stably obtained. In addition, the sample liquid 9 is stored in the liquid reservoir chamber 6.
Since it is placed inside the device, it is not necessarily necessary to use it stationary, and it is easy to handle, and it can also be used upside down or tilted. Furthermore, in the above-mentioned apparatus 1, a sample liquid inlet 7 is provided in the side wall of the liquid reservoir sealed container 2, slightly below the membrane 5 arrangement position, and the sample liquid 9 is introduced into the liquid reservoir chamber 6 from this sample liquid inlet 7. Since the sample solution is injected, the sample solution does not adhere to the inner wall of the diffusion tube 4 when injecting or replenishing the sample solution 9, making it easy to handle and stabilizing in a relatively short time after starting use. do.

In the above device, the sample liquid inlet 7 is drilled in the side wall of the liquid reservoir sealed container 2, and the sample liquid 9 is injected into the liquid reservoir chamber 6 from there. The means to enter are not limited to this,
For example, as shown in FIG. 2, by forming a fitting part 10 slightly below the membrane installation position of the liquid reservoir sealed container 2, the liquid storage closed container 2 can be connected to the upper container 2a and the lower side with the boundary slightly below the membrane installation position. After injecting the sample liquid 9 into the lower container 2b from the opening of the lower container 2b, the upper container 2a is placed on the lower container 2b, and the sample liquid 9 is poured into the liquid reservoir chamber 6. You can also put
Furthermore, other means may also be used.

In addition, in the present invention, there is no particular restriction on the material of the membrane through which the vapor of the sample liquid can pass, but materials that have pores and do not get wet with the sample liquid, such as Teflon membranes, silicone membranes, glass fiber membranes, etc., are preferred. Can be used. In this case, it is preferable to use a membrane having a pore diameter of 0.1 to 100 μm and a membrane thickness of 0.01 to 0.1. Note that the means for disposing the membrane within the liquid reservoir closed container is not particularly limited, and may be disposed by means such as adhesion.

In addition, when using the standard gas generation device of this invention, the standard gas concentration depends on the ambient temperature, dilution gas flow rate,
It is determined by the length of the diffusion tube, the cross-sectional area of the sample diffusion path, etc., and the standard gas concentration can be set by the thickness, pore diameter, surface area, etc. of the membrane.

In this case, in the standard gas generation device of the present invention, the liquid reservoir sealed container 2 and the diffusion tube 4 are removably connected to make the diffusion tube 4 replaceable, and the diffusion tube 4 attached to the liquid reservoir sealed container 2 is connected to the diffusion tube 4 in a detachable manner. It can be changed to one having various lengths and diffusion path cross-sectional areas, thereby making it possible to obtain standard gases of various concentrations using the same liquid reservoir sealed container 2. In other words, the concentration of the standard gas generated is determined by equation (1), which will be described later.
Here, Dr is the length of the diffusion tube 4 and the cross-sectional area of the diffusion path,
Determined by dilution gas temperature and sample vapor pressure. Therefore,
The concentration of the standard gas generated can be changed by changing the flow rate and temperature of the diluent gas, the length of the diffusion tube 4, and the cross-sectional area of the diffusion path. If you change the standard gas concentration by changing the temperature, it will take time to stabilize after changing the temperature. On the other hand, if the diffusion tube 4 is formed to be replaceable as described above, for example, one liquid reservoir sealed container 2 is provided for each sample, and diffusion tubes having various lengths and diffusion path cross-sectional areas are attached to this. By installing it, standard gases of various concentrations can be easily obtained while keeping the dilution gas flow rate constant. Note that the means for removably connecting the liquid reservoir sealed container 2 and the diffusion tube 4 is not particularly limited;
For example, as shown in FIG. 3, a ferrule front 4a and a ferrule rear 4b are arranged on the base end side of the diffusion tube 4, and the diffusion tube 4 is connected to the base end of the diffusion tube 4 formed in the liquid reservoir sealed container 2. The diffusion tube 4 is inserted into the insertion portion 2a and the insertion hole 2b, and a cap nut B having a diffusion tube insertion hole A drilled in the center is engaged with the screw thread 2c of the diffusion tube insertion portion 2a. As shown in Fig. 4, the proximal end of the diffusion tube 4 is inserted into the insertion hole 2b of the diffusion tube insertion part 2a, and a diffusion tube insertion hole A is drilled in the center and the inside is fixed and sealed. A method is preferably adopted in which the insertion point of the diffusion tube 4 is fixed and sealed by engaging the cap nut B equipped with the O-ring C with the screw thread 2c of the diffusion tube insertion portion 2a. When the tube 4 is inserted into the liquid reservoir sealed container 2 by rubbing, the vapor of the sample liquid flows between the liquid reservoir sealed container 2 and the diffusion tube 4.
It is possible to effectively prevent diffusion from the contact area.

FIG. 5 shows an example of the use of the standard gas production apparatus of the present invention.

In FIG. 5, reference numeral 11 denotes a box-shaped constant temperature holder, and the upper wall of this constant temperature holder 11 is provided with a standard gas production device mounting hole 12.
The lower part (the upper part in Fig. 5) of the standard gas production apparatus 1 of the present invention is airtightly attached to 2.
As a result, the standard gas production device 1 becomes the constant temperature holder 11.
It is glued to the constant temperature holder 11 so that it is in an inverted state inside. Note that the standard gas production apparatus 1 has almost the same configuration as the apparatus shown in FIG.
Identical components are given the same reference numerals and their explanations are omitted; however, in this device, the constant temperature holder 11
A sample liquid inlet 7 is bored in the lower wall (upper wall in FIG. 5) of the liquid reservoir airtight container 2 exposed to the outside, and a stopper 8 is inserted into this sample liquid inlet 7. A sample liquid is injected into the liquid reservoir chamber 6 from the injection port 7. In addition, the constant temperature holder 1
A diluent gas inlet 13 is formed in the upper part of one side wall 11a of the 1, and a dilute gas outlet 14 is formed in the lower part of the other end wall 11b opposite to the one side wall 11a.
The diluent gas that has flowed into the thermostatic holder 11 from the diluent gas inlet 13 flows through the thermostatic holder 11 and then flows out of the thermostatic holder 11 from the diluent gas outlet 14. .

When producing a standard gas using the apparatus shown in FIG.
After injecting the sample liquid into the liquid reservoir chamber 6 inside, the stopper 8 is inserted into the sample liquid injection port 7. Next, when diluting gas is continuously introduced into the constant temperature holder 11 from the diluting gas inlet 13, after passing through the membrane 5, the diluting gas is introduced into the diffusion tube 4.
The vapor of the sample liquid 9 in the liquid storage chamber 6 which has diffused through the sample diffusion path 3 and flowed out of the diffusion tube 4 is diluted with the diluent gas, and then flows out from the dilution gas outlet 14 as a standard gas. It is.

In the apparatus shown in FIG. 5, the standard gas generation device 1 of the present invention is attached to a constant temperature holder 11 in an inverted state, and the lower wall of the liquid reservoir sealed container 2 (in FIG. 5, the upper A sample liquid inlet 7 is bored in the wall) and the sample liquid 9 is injected into the liquid reservoir chamber 6 from this sample liquid inlet 7.
There is no need to remove the standard gas generation device 1 from the thermostatic holder 11 when injecting the sample liquid 9 or replenishing it.
Moreover, the sample liquid can be injected and replenished without adhering to the inner wall of the diffusion tube 4.

As explained above, the standard gas generation device according to the present invention includes a liquid reservoir sealed container into which a sample liquid is placed, and is connected to this liquid reservoir sealed container, and an internal sample diffusion path is connected to the liquid reservoir sealed container. In the standard gas production apparatus, the standard gas production apparatus has a diffusion tube communicating with the liquid reservoir, and the vapor of the sample liquid in the liquid reservoir closed container flows out after diffusing through the sample diffusion path of the diffusion tube. A liquid reservoir chamber is formed in the liquid reservoir airtight container by partitioning the inside of the sealed container with a membrane through which the vapor of the sample liquid can pass, and after the vapor of the sample liquid placed in this liquid reservoir chamber passes through the membrane. By making the sample diffusion path of the diffusion tube diffuse, it is possible to stably obtain a standard gas with a wide concentration range of ppb to ppm level, and the sample liquid does not adhere to the inner wall of the diffusion tube, making it easier to handle. is simple.

Next, an experimental example using the standard gas generation device of the present invention will be shown to specifically explain the effects of the present invention.

[Experiment example]

Toluene was injected into the reservoir chamber of the device shown in Figure 1, which had a diffusion path cross-sectional area of 0.0314 mm ² , a diffusion tube length of 6 cm, and a Teflon membrane (Fluoropore FS-D10, diameter 12φ) as the membrane, and the diluent gas flow rate was adjusted. A standard gas was produced by a conventional method under conditions of 1/min and a steam temperature of 21 to 22°C, and the toluene concentration in the standard gas was determined using a methane-calibrated total hydrocarbon meter. Similar experiments were also conducted using the standard gas generation device in an inverted position. Note that concentration measurement uses FID as a detector, and temperature
The measurement conditions were 80°C, hydrogen 27ml/min, sample 10ml/min, and auxiliary combustion air 400ml/min.

As a result, the toluene concentration in the standard gas obtained was 0.66 ppm both when the vapor outlet of the diffusion tube was directed upward and downward. Therefore, by using the standard gas generation device of the present invention, it is possible to obtain standard gas at a flow rate comparable to that obtained by using a diffusion tube, and the effect does not change even when used upside down. This was recognized. In addition, with the standard gas generation device mentioned above, the sample liquid does not adhere to the inner wall of the diffusion tube when injecting the sample liquid, the time required for stabilization is short, less than 3 minutes, and there is no need to use it stationary. It was extremely easy to handle.

For reference, a case will be described in which a standard gas is produced by a normal method using a diffusion tube.

The concentration of the standard gas generated by the diffusion tube is calculated using the following formula (1).

C= Dr (formula (2) below).

K = 22.4M × T273 × P760 ... (2) M: Molecular weight of sample liquid T: Diluent gas temperature P: Atmospheric pressure (mmHg) Diffusion rate D _r is determined by weighing the actual amount of decrease in the sample, and is calculated as follows. Calculated using formula (3). in this case,
Measurements are made by keeping the diffuser tube at a constant temperature and flowing a constant flow rate.

D _r = m×10 ⁹ T (3) m: sample reduction amount (g) T: weighing interval (min) However, the diffusion constant is estimated by the following formula (4).

D _r =1.90×10 ⁴・T・D _p・M・AL・log PP−ρ
...(4) T: Steam temperature (〓) D _p : Diffusion constant D _p = D ( TT _p ) ² P _p P (cm ² /sec) M: Sample molecular weight (g) A: Diffusion path cross-sectional area (cm ² ) L: Diffusion tube length (cm) P: Atmospheric pressure (mmHg) ρ: Sample vapor pressure (mmHg at T) Therefore, toluene was injected into a diffusion tube with an inner diameter of 2 mm and a length of 10 cm. death,
When standard gas is produced under the conditions of dilution gas flow rate 1/min and steam temperature 303〓, D _r = 1.9×10 ⁴・303.0.0849・92.13・0.031410・
0.0215=3054 (ng/min) C=3054×〓〓×〓〓×〓〓/1000=0.76ppm, and in order to obtain 10ppm standard gas at a flow rate of 1/min, the inner diameter of the diffusion tube should be 5 mm and the length of the diffusion tube should be 5 mm. difference
All you need to do is use a 4.75mm differential tube.

Therefore, it is recognized that the diffuser tube is suitable for obtaining ppm level standard gas at a large flow rate. It is difficult to handle, as it tends to adhere to the inner wall of the pipe and needs to be left standing.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing a standard gas production apparatus according to an embodiment of the present invention, and FIGS. 3 and 4 respectively show a structure in which a diffusion tube is removably connected to a liquid reservoir sealed container. A partially omitted sectional view showing
FIG. 5 is a schematic sectional view showing an example of a standard gas generation device using the standard gas production device of the present invention. 1...Standard gas production device of the present invention, 2...Liquid reservoir sealed container, 3...Sample diffusion path, 4...Diffusion tube,
5...membrane, 6...liquid reservoir chamber.

Claims (1)

[Scope of utility model registration request] It has a liquid reservoir sealed container into which a sample liquid is placed, and a diffusion tube connected to this liquid reservoir sealed container and whose internal sample diffusion path communicates with the liquid reservoir sealed container. In the standard gas production device in which the vapor of the sample liquid diffuses through the sample diffusion path of the diffusion tube and then flows out to the outside, the inside of the liquid reservoir sealed container is partitioned with a membrane through which the vapor of the sample liquid can pass. A liquid storage chamber is formed in the liquid storage sealed container, and the vapor of the sample liquid introduced into the liquid storage chamber permeates the membrane and then diffuses through the sample diffusion path of the diffusion tube. Equipment for standard gas production.