JP4570148B2 - Gas detector - Google Patents

Description

  The present invention relates to a gas detection device that detects the concentration of a gas to be detected as a change in optical density by the reaction between the gas to be detected and a reagent, and more particularly to a gas detection device that can deal with a gas to be detected that includes interference components.

A gas detection device using a color reaction between a gas to be detected and a reagent includes a means for introducing a gas to be detected into a gas detection material configured by impregnating or applying a reagent to a base material, and an optical of the gas detection material. It is comprised by the means to detect a density | concentration, and it can respond to the detection of the wide density | concentration range from a very low density | concentration to a high density | concentration by adjusting the contact time of a gas detection material and to-be-tested gas.
By the way, when such a gas detection material is taken as an example in which hydrogen cyanide (HCN) is a detection target, a monovalent copper hydrate hydrate that produces hydrogen cyanide to be detected in the reagent is used. By reacting with the copper ion of

The optical density is detected as a change in the molecular structure of the redox indicator in the reagent.
For this reason, when an attempt is made to detect each gas (chlorine, hydrogen cyanide) in an atmosphere containing an oxidizing gas, for example, chlorine (Cl2) and hydrogen cyanide, the gas detection material for hydrogen cyanide also reacts with chlorine to increase the concentration of hydrogen cyanide. There is a problem that a measurement error occurs.
In order to solve such a problem, it is conceivable to use a filter, but there is a problem that not only chlorine but also hydrogen cyanide, which is a gas to be detected, is removed, resulting in a detection error.

  The present invention has been made in view of such problems, and the object thereof is to detect hydrogen cyanide using a color reaction that can selectively remove chlorine and measure hydrogen cyanide with high accuracy. To provide a chlorine gas removal filter suitable for an apparatus.

  In order to achieve such a problem, the invention of claim 1 is a filter of a hydrogen cyanide detection device that detects hydrogen cyanide as an optical density with a reagent by reacting hydrogen cyanide with a hydrate of copper (II) acetate. The impregnating material having N.I. The impregnation material is accommodated in a container impregnated with N-diethyl-P-phenylenediamine sulfate and having a connection port formed at a position where a flow passing through the impregnation material is generated.

  According to a second aspect of the present invention, the impregnating material is constituted by a granular material made of pulp.

  In the invention of claim 3, the impregnating material is accommodated in a tubular body from which the impregnating material can be visually recognized.

  According to a fourth aspect of the present invention, the impregnating material contains a hygroscopic agent.

  According to the invention of claim 1, N.I. N-diethyl-P-phenylenediamine sulfate reacts with chlorine and is fixed to the impregnating material, but is insensitive to hydrogen cyanide as a gas to be detected. Can be detected.

  According to invention of Claim 2, a contact area with sampling gas can be ensured easily and chlorine gas can be removed reliably.

  According to the invention of claim 3, the breakthrough time of the filter can be easily known.

  According to the invention of claim 4, since the impregnating material can be maintained in a wet state, N.I. N-diethyl-P-phenylenediamine sulfate can react efficiently with chlorine and reliably remove chlorine.

Therefore, details of the present invention will be described below based on the illustrated embodiment.
FIG. 1 shows an embodiment of a gas detection device using a chlorine removal filter of the present invention. The detection paper type gas detection device 1 includes a light emitting element 2 and a light receiving element 3. In response to the negative pressure from the sampling pump 7 and the tape transport mechanism 6 that transports the detection paper 5 processed into a tape shape to the measurement head 4 at regular intervals, the detection paper 5 is jointed with the measurement head 4. The suction head 8 is in contact with the test gas.

  A chlorine removal filter 10 characterized by the present invention is detachably connected to the gas inflow side of the measuring head 4 via a connector 8.

  As shown in FIG. 2, the chlorine removal filter 10 has a gas inlet 11 at one end and a gas outlet 12 at the other end, and is inert to a test gas such as glass or a polymer material. Preferably, a tubular body 13 formed of a material whose color change can be visually recognized from the outside contains a granular material, for example, a chlorine gas absorbent 14 in which granular pulp is impregnated with an agent that absorbs chlorine.

  Chlorine gas absorbers are easy to dispose of and have a water-absorbing granular material such as granular pulp obtained by shaping pulp into a granular form (registered trademark “Visco Pearl” of Rengo Co., Ltd.). It is constituted by impregnating N-diethyl-P-phenylenediamine sulfate (C2H5) 2NC6H4NH2 · H2SO4 and volatilizing the solvent. Preferably, it is desirable to keep the pulp always wet by mixing a hygroscopic agent, for example, a polyhydric alcohol such as glycerin.

  In addition, the hydrogen cyanide detection material is applied to the base material with copper (II) acetate, an antioxidant, a humectant, and a color developing agent that changes color due to the oxidizing power of copper cyanide as disclosed in JP 2001-013076. It is constructed by impregnation.

  More specifically, copper acetate (II) [(CH 3 COO) 2 Cu H 2 O] hydrate 0.05 wt%, antioxidants such as butylhydroxyl toluene 0.2 wt%, color formers such as tetramethyldiaminodiphenylmethane 0.15 wt% And a humectant, for example, 15 ml of a polyhydric alcohol such as glycerin or ethylene glycol, is dissolved in an easily evaporable organic solvent such as methanol so that the total amount becomes 100 ml. For example, a filter paper made of cellulose is impregnated, and the organic solvent is volatilized while heating as necessary.

  In order to promote the reaction with the test gas, a sheet material in which fine powders such as silica gel and alumina are mixed in advance is used, or fine powders such as silica gel and alumina are mixed in the coloring solution and supported on the sheet material. Is desirable.

  In this embodiment, when the sampling pump 7 is operated, the chlorine gas contained in the test gas flowing into the chlorine removal filter 10 is N.P. It reacts selectively with N-diethyl-P-phenylenediamine sulfate and is fixed to the chlorine gas absorbent 14 so that it cannot flow downstream.

  On the other hand, the hydrogen cyanide that is the detection target in the test gas that has flowed into the chlorine removal filter 10 passes through the filter material and moves to the gas detection material to generate copper cyanide. Color reaction is caused to tetramethyldiaminodiphenylmethane which is an indicator. As a result, a blue reaction mark proportional to the concentration of hydrogen cyanide or the accumulated time is formed on the tape 1, and the concentration of hydrogen cyanide is measured by detecting the relative optical density of the reaction mark with the light emitting element 4 and the light receiving element 5. can do.

  Of course, since chlorine in the gas to be detected has been removed, the optical density of the reaction trace on the tape 1 is related only to hydrogen cyanide, and the concentration of hydrogen cyanide can be detected with high accuracy.

  On the other hand, the chlorine gas absorbing material 14 which is a granular material accommodated in the tubular body 13 reacts with chlorine in order from the inflow side and discolors. Therefore, it indicates the standard of the timing for replacing the chlorine removal filter 10 or replacing the chlorine gas absorbent 14.

  FIG. Prepare a solution of N-diethyl-P-phenylenediamine sulfate 0.5 wt%, glycerin 15 vol%, and methanol 85 vol%, and immerse the granular pulp in this for 5 minutes to fully impregnate, and then remove the granular pulp. A chlorine gas removing filter in which 3 g of a chlorine gas absorbing material 14 from which methanol has been volatilized by natural drying for about 1 hour is housed in a tubular body having an inner diameter of 22 mm and a length of 70 mm is formed. It shows the change of the indicated value when chlorine gas with a concentration of 2 ppm is sucked at 450 ml / min. It can be seen that the influence of chlorine can be removed up to about 5 minutes in this example.

Needless to say, the filter life, that is, the time until breakthrough is N.P. Since it is proportional to the amount of N-diethyl-P-phenylenediamine sulfate, this amount can be adjusted.
That is, N.I. When the amount of N-diethyl-P-phenylenediamine sulfate is, for example, 5 times and the concentration of chlorine is 2.5 times, the lifetime is 2 ppm as shown in FIG. It is 5 times that in terms of chlorine.

  In the above-described embodiment, N.I. Since the granular body is impregnated with N-diethyl-P-phenylenediamine sulfate and accommodated in the tubular body 13, the breakthrough state can be determined as a detection tube. When the amount is known in advance, the breakthrough time is clear, so a sheet having air permeability, such as filter paper, is used as the impregnating material, and a connection port is formed at a position where a flow passing through the sheet is generated. It is clear that the same effect can be obtained even if it is housed in a separate container and formed into a membrane filter shape.

  Moreover, although the tape-shaped detection material is used in the above-mentioned embodiment, it is clear that the same effect can be obtained even if the detection material is cut into pieces and configured as a tab accommodated in an openable container. .

It is a figure which shows one Example of the gas detection apparatus using the chlorine gas removal filter of this invention. It is sectional drawing which shows one Example of the chlorine gas removal filter of this invention. FIGS. 1A and 1B are diagrams showing the effect of removing chlorine gas, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Detection paper type gas detection apparatus 7 Sampling pump 10 Chlorine gas removal filter 11 Gas inlet 12 Gas outlet 13 Container 14 Chlorine gas absorber

Claims (4)

A hydrogen cyanide detection device filter that reacts hydrogen cyanide with a hydrate of copper (II) acetate and detects the optical density with a reagent,
N. Chlorine gas removal for a hydrogen cyanide detector constructed by impregnating N-diethyl-P-phenylenediamine sulfate and containing the impregnating material in a container having a connection port formed at a position where a flow passing through the impregnating material is generated filter.   The chlorine gas removal filter for a hydrogen cyanide detector according to claim 1, wherein the impregnating material is constituted by a granular material made of pulp.   The chlorine gas removal filter for a hydrogen cyanide detector according to claim 2, wherein the impregnating material is accommodated in a tubular body from which the impregnating material can be visually recognized.   The chlorine gas removal filter for a hydrogen cyanide detector according to any one of claims 1 to 3, wherein the impregnating material contains a hygroscopic agent.

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