JP3319874B2 - Detection method of absorption limit of absorbent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for judging the life of an absorbent used in an absorbent can for a gas mask.
The present invention relates to a method for detecting an absorption limit of a gaseous substance to an absorbent.

[0002]

2. Description of the Related Art A gas mask is a type of filtration respirator that removes toxic gas and the like in the air sucked by the lung force of a wearer. There are various types of gas masks, and they are classified into three types depending on the configuration: an isolation type, a direct connection type, and a direct connection type small size. The isolation ceremony is
It consists of a face, a connecting pipe, and a large absorption. It is called an isolation type because the facepiece and the absorption can are separated and connected by a connecting pipe. The direct connection consists of a facepiece and a canister. It is called a direct connection type because a medium-sized absorbent can is used and the absorbent can is directly connected to the facepiece. The direct-connect miniature consists of a facepiece and a canister.
The configuration is the same as that of the direct connection type, but is called a direct connection type small size because a small absorbent can is used.

[0003] In each case, an absorbent can filled with an absorbent is used. The detoxification capacity of the canister is finite, and the concentration of toxic gas permeating increases as the capacity of the drug in the canister is lost. A state in which the concentration of toxic gas passing through the absorbent can exceeds the maximum permissible limit is called breakthrough. There is a certain relationship between the breakthrough time and the environmental concentration, and the time (lifetime) during which the absorber can be used is shorter at higher concentrations of toxic gas,
Longer at lower concentrations. When the breakthrough time (use time limit) is reached, it is necessary to immediately replace the can with a new one.

[0004]

The most important thing in using a gas mask is the time until the breakthrough (remaining effective time).
Check if necessary and replace the can with a new one if necessary. As a method for determining the remaining effective time (life), the following method is conventionally known. (1) A method of judging the life as having reached the use limit time calculated from the breakthrough card attached to the absorbent can and the environmental gas concentration. However, the breakthrough card used in this method is created under the condition that the toxic gas concentration and the temperature and humidity are constant, and the actual use conditions are not always constant. Therefore, in practice, this method cannot accurately determine the life. (2) A method of determining the life when a odor or irritation is felt during use. This method cannot be used for odorless or low-concentration highly toxic gases (such as hydrocyanic acid gas).

(3) A method in which the weight of an absorbent can is measured, and the life is determined when the increase amount reaches a certain value. In this method, since the weight of the absorber at the end of its life varies depending on the type of toxic gas and the temperature and humidity, it is not possible to determine the life accurately. In addition, there is also a complication that it is necessary to take out the absorbent can and measure the weight. (4) A method in which a diffusion type detection tube filled with a detection agent is attached to the outlet side of the absorption can to utilize a color change due to a reaction between the toxic gas and the detection agent. In this method, the type of the detecting agent differs depending on the type of toxic gas, and the type of toxic gas
Different detection agents need to be used. Further, there is a problem that the structure of the absorbing can becomes complicated.

At present, the method (1) for determining from the breakthrough curve diagram attached to the absorbent can is practical because it is simple and has relatively high reliability. That is, at present,
When the usage time calculated from the breakthrough card attached to the absorbent can and the environmental gas concentration has been reached, the absorbent can is replaced. However, as described above, even with this method, it cannot be said that the life of the absorber can be reliably determined. In addition, since the type of gas is related to human life depending on the type of gas, it is desired to provide a more accurate and reliable method for determining the life of an absorber.

It is an object of the present invention to provide a new method for reliably and accurately detecting the life of an absorbent such as an absorbent can.

[0008]

SUMMARY OF THE INVENTION The present invention is a method for detecting the absorption limit of a gaseous substance to an absorbent, comprising the steps of: The present invention also relates to a method of detecting the absorption limit of the absorbent from the degree of expansion of the volume of the porous carbon by exposing to the gaseous substance. Hereinafter, the present invention will be described.

The "method of detecting the absorption limit of a gaseous substance to an absorbent" of the present invention is characterized by using "porous carbon which expands in volume when gaseous substance is absorbed". “Porous carbon that expands in volume when absorbing gaseous substances” is described in Activated Carbon Technology Research Group Material No. 102
(1990), pp. 2-9, the ester carbonized porous carbon can be used. Porous carbon obtained by the ester carbonization method is, for example, 4-phenyl-1,
It can be obtained by impregnating silica gel with an organic compound such as 2-dioxybenzene, esterifying, heat-treating and carbonizing to a carbon-coated silica gel, and dissolving and removing the silica from the silica gel with hydrofluoric acid or the like.

The ester carbonized porous carbon varies depending on the production method and type, and also the type and amount of the compound to be adsorbed, but usually about 5% by adsorbing the compound.
It expands in the range of ３０30%. The ester carbonized porous carbon also has a property of rapidly shrinking and returning to its original size by desorbing the adsorbed compound.

The gaseous substances to be used in the present invention include gaseous organic compounds and inorganic compounds. Examples of the organic compound include various compounds used as an organic solvent, for example, benzene, toluene, xylene, chloroform, carbon tetrachloride, butanol, propanol, octane, heptane,
Examples thereof include cyclohexane, ethanol, hexane, pentane, and methanol. Examples of the inorganic compound include halogen (eg, chlorine), acid gas (eg, hydrogen chloride gas), carbon monoxide, ammonia, sulfurous acid, hydrocyanic acid, hydrogen sulfide, methyl bromide, and the like.

The method of the present invention is a method for detecting the absorption limit of the absorbent that has absorbed the gaseous substance. Here, the absorption limit is, for example, a breakthrough state exceeding the maximum permissible limit in the case of an absorbent can. In the method of the present invention, the above "porous carbon which expands in volume when absorbing gaseous substances"
The absorption limit of the absorbent is detected from the degree of expansion of the volume (hereinafter sometimes referred to as porous carbon). As described above, the expansion coefficient of the porous carbon varies depending on the type of the compound to be absorbed. However, the degree of expansion of the porous carbon when the adsorbent provided reaches the absorption limit is determined in advance. Then, by measuring that the porous carbon has expanded to a predetermined extent, the absorption limit of the absorbent is detected.

[0013]

EXAMPLES The method of the present invention will be further described below with reference to examples.

For example, as the simplest method, the absorption limit of the absorbent can be detected by visually measuring the degree of expansion of the volume of the porous carbon. For example, FIG.
And 2, the absorbent 1 and the porous carbon 2 are arranged so that the end 20 of the porous carbon 2 can be seen from the outside.
Is stored in an absorption can (not shown). And absorbent 1
The extent to which the porous carbon expands when reaches the absorption limit is measured in advance, and a mark (absorption limit mark 3) is attached to the position where the end 20 of the porous carbon 2 reaches at that time. . Gas absorption starts from the state of (1) in FIG. 1 or 2. Then, the absorption of the gas proceeds, and the end portion 20 of the porous carbon 2 reaches the absorption limit mark 3 in the state (2). At this point, it can be detected that the absorbent has reached the absorption limit.

However, the degree of expansion of the porous carbon when the absorbent reaches the absorption limit differs between the embodiment of FIG. 1 and the embodiment of FIG. This is because, in the embodiment of FIG. 1, the gaseous substance reaching the porous carbon is relatively low in concentration since the gaseous substance reaches the porous carbon after passing through the absorbent. On the other hand, in the embodiment of FIG. 2, the gaseous substance passes through the porous carbon simultaneously with the absorbent, so that the concentration of the gaseous substance passing through the porous carbon is high. Therefore, in the embodiment of FIG. 1 and the embodiment of FIG.
The degree of expansion of the porous carbon when the absorbent reaches the absorption limit is different, and accordingly, according to each embodiment, the position of the mark when the absorbent reaches the absorption limit needs to be determined.

The degree of expansion of the volume of the porous carbon is as follows:
In addition to vision, it can also be measured using physical or chemical methods. For example, the physical method includes an electrical method. For example, as shown in FIG. 3, electrodes 4 and 4 ′ are provided so as to be adjacent to the porous carbon 2.
The electrode 4 is fixed to the porous carbon 2 and moves as the porous carbon 2 expands. The electrode 4 ′ is fixed at a position facing the electrode 4. The gas absorption starts from the state (1) in FIG. 3 and the gas absorption proceeds, and the electrodes 4 and 4 ′ are brought into contact and energized in the state (2) to detect the absorption limit of the absorbent. be able to. By energization, for example, an alarm can be used to emit a warning sound or an alarm lamp can emit light.

Further, as another physical method, there is a method of measuring a change in pressure caused by expansion of the volume of porous carbon. As shown in FIG. 4, when the absorbent reaches the absorption limit, a pressure sensor 6 is provided at a position where the end portion 20 of the porous carbon 2 is located, and when the absorbent 1 reaches the absorption limit, the pressure sensor 6 Emits an electrical signal so that the absorbent can detect the absorption limit. The electrical signal is
Similar to the above, it can be sent to an alarm or a warning light.

As a method for chemically measuring the degree of expansion of the volume of the porous carbon, for example, as shown in FIG. 5, instead of the above-mentioned electric pressure sensor, for example, a pressure-sensitive paper 7 which causes a chemical change by pressure is used. Can be used. The pressure-sensitive paper 7 is colored by being pressed by the end portion 20 of the porous carbon 2, and the absorbent can detect the absorption limit.

That is, in the present invention, porous carbon having a characteristic of expanding in volume when gas is adsorbed is filled in an absorption can for a gas mask, and the absorption of toxic gas is performed by utilizing the volume expansion when the toxic gas is absorbed. The life of the can can be determined. (1) The electrodes of the electric circuit having the alarm are connected by utilizing the volume expansion when the gas is absorbed. (2) Discoloration of pressure-sensitive paper is caused by utilizing volume expansion when gas is absorbed. (3) The change in volume is measured electrically or visually by utilizing the volume expansion when the gas is absorbed. (4) Pressure is applied to the pressure sensor using volume expansion when gas is absorbed.

Reference Example Method for Preparing Porous Carbon Microbead Silica Gel 4B by Fuji Devison Chemical
(Particle size: 100-200 mesh, surface area: 473 m
² / g, pore volume 0.86 cm ³ / g, average pore diameter:
(7.3 nm) was mainly used as a raw material, and porous carbon was prepared by an ester carbonization method. Silica gel impregnated with 4-phenyl-1,2-dioxybenzene (weight percentage: 5
(0%) was heat-treated at 300 ° C. for 1 hour in a nitrogen stream to cause an esterification reaction on the surface, and unreacted organic compounds were removed by washing with acetone. The esterified silica gel was heat-treated at 700 to 1000 ° C. under reduced pressure (<5 Pa) to carbonize the organic compound chemically bonded to the silica gel surface to obtain a carbon-coated silica gel. Furthermore, the silica gel is dissolved and removed by treating it with hydrofluoric acid,
After washing with water, air drying was performed at 120 ° C. to obtain porous carbon.

The results of measuring the expansion rate (maximum expansion rate) of the volume of the porous carbon upon adsorption of the substance for various substances are shown below. Benzene: 31% Toluene: 32% Xylene: 32% Chloroform: 31% Carbon tetrachloride: 29% Butanol: 27% Propanol: 26% Octane: 26% Heptane: 25% Cyclohexane: 24% Ethanol: 24% Hexane: 23% Pentane: 21% Methanol: 20%

[0022]

The method of the present invention has the following advantages. (A) It can be used in an apparatus having a relatively simple structure. (B) There are many types of gases that can be handled. (C) It is hardly affected by temperature and humidity. (D) The life of the absorber can be determined without removing the mask.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a method for detecting an absorption limit of an absorbent according to the present invention.

FIG. 2 is a schematic explanatory view of a method for detecting an absorption limit of an absorbent according to the present invention.

FIG. 3 is a schematic explanatory view of a method for detecting an absorption limit of an absorbent according to the present invention.

FIG. 4 is a schematic explanatory view of a method for detecting an absorption limit of an absorbent according to the present invention.

FIG. 5 is a schematic explanatory view of a method for detecting an absorption limit of an absorbent according to the present invention.

Continuation of the front page (56) References JP-A-57-166172 (JP, A) JP-A-56-89056 (JP, A) JP-A-60-217205 (JP, A) JP-A-57-125760 (JP, A) JP-A-2-150758 (JP, A) JP-A-55-147123 (JP, A) JP-A-4-80554 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB G01N 19/10 A62B 18/02 G01N 7/04 JICST file (JOIS)

Claims (8)

(57) [Claims] 1. A method for detecting an absorption limit of a gaseous substance to an absorbent, the method comprising: exposing porous carbon, which expands in volume when absorbing the gaseous substance, to the gaseous substance together with the absorbent; A method of detecting the absorption limit of the absorbent from the degree of expansion of the volume of the porous carbon. 2. The method according to claim 1, wherein the porous carbon that expands in volume when absorbing a gaseous substance is an ester carbonized porous carbon. 3. The method according to claim 1, wherein the gaseous substance is a gaseous organic or inorganic compound. 4. The method according to claim 1, wherein the degree of expansion of the volume of the porous carbon is measured physically or chemically. 5. The method according to claim 4, wherein the physical measurement of the degree of expansion of the volume of the porous carbon is performed by opening and closing electrical contacts. 6. The method according to claim 4, wherein the physical measurement of the degree of expansion of the volume of the porous carbon is performed using a pressure sensor. 7. The method according to claim 4, wherein the chemical measurement of the degree of expansion of the volume of the porous carbon is performed using pressure-sensitive paper. 8. The method of claim 1, wherein the degree of volume expansion of the porous carbon is visually sensed.