DE1067691B - Breathing filter to protect against carbon dioxide - Google Patents

Description

GERMAN

The invention relates to respiratory filters for protection against carbon oxide. With the known filters of this type the filtering of the breathing air to render the carbon oxide harmless is effected by the Air is passed through a catalyst layer consisting of manganese and copper oxides, which is known in respiratory protection technology under the name "Hopkalite". The catalytic filter media after Type of Hopkalite have a very long catalytic effect, which only thereby weakened and finally becomes ineffective if it absorbs a certain amount of water vapor from the air sent through it to have. In order to keep the filter operational for a long time, it is necessary to use the catalytic Upstream of the filter material, a filter layer in which the water vapor in the air is bound. To the In most cases, the water-binding prefilter layers are calcium chloride of coarser or finer grain size been used. Such a calcium chloride dry layer does not prove itself in those cases where the Air contains a lot of water vapor because the grains melt and bake in the absorbed water of hydration and thus impermissibly increase the flow resistance of the filter after a certain time. In some cases, however, the fact of the increase in breathing resistance also became an indication made use of the approaching exhaustion of the filter.

It is also known to use silica gel as the desiccant, but in the same amount does not have as high a capacity for water vapor as calcium chloride, but very energetic is an effective drying agent. It is also known to use activated carbon together with silica gel as a separate layer to use, which has the advantage that it also has a certain drying effect Foreign matter from the air, d. H. Gas components removed by the catalyst through their chemical action could possibly be harmful. Such foreign gases would be z. B. Acid fumes and also Hydrogen sulfide gas, which convert the oxides of the catalyst into salts of the acids in question and this would destroy the catalytic effect prematurely.

For carbon oxide filters that are to be used in places with particularly high humidity, such as B. in the well-known filter self-rescuers used in the mine, which compared to the other carbon oxide filters have significantly smaller dimensions, a silica gel was used as the desiccant layer, that is loaded with calcium chloride. This dry matter is characterized by the fact that it is next to a high absorption capacity also offers the advantage that their grains do not bake and the patency Breathing filter to protect against carbon dioxide

Applicant:

Auergesellschaft Aktiengesellschaft,
Berlin N 65, Friedrich-Krause-Ufer 24

Dipl.-Chem. Dr. Karl-Heinz Schulte-Schrepping,
Berlin-Charlottenburg,
and Dipl.-Chem. Günter Koh, Berlin,
have been named as inventors

the desiccant layer for the breathing air is maintained for a relatively long time. the The resistance time of the desiccant layer is now responsible for the service life and ability to work of the entire filter. As I said before, the catalytic filter layer works properly as long as it does is not poisoned by the ingested water.

The invention has therefore set itself the task for carbon oxide filters of the type described in which Due to the small dimensions of the filter, only very short residence times are available for the filter effect stand to create desiccants for the air breathed through, which have an even higher absorption capacity for water vapor in these short residence times and retain the absorbed water vapor, so that it also occurs when the filter layers are heated, which occurs when high carbon oxide concentrations are oxidized can occur, is not made free again from the desiccant layer and thereby can optionally enter the catalyst layer. This object is achieved according to the invention achieved that activated carbon is connected upstream of the catalyst mass, which in a known manner with 15 to 50%, preferably 30%, calcium and / or lithium halides is impregnated.

Furthermore, it has been found according to the invention that by the impregnation described Desiccants manufactured using conventional gas mask carbons do not achieve the highest performance, but prefer those that are referred to as "overactivated" in the practice of coal production. Such overactive

909 639/188

Claims (1)

3 4 fourth coals are made for gas adsorption, how to filter CO with desiccant they must aim for gas mask filters, not suitable. unimpregnated silica gel 33 minutes But they have for impregnation with dry silica gel impregnated with 30% CaCl ₀ 66 minutes provide a particularly cheap normal gas mask carbon for drying purposes, imprä ^: Structure in terms of distribution between roughly 5 gnated with 30 ° / »CaCl ₂ 79 minutes and fine capillaries. overactivated carbon impregnated with For applying and loading the activated carbon with 30% CaCl ₂ 97 minutes Gas mask charcoal with 30% Li Cl IOO minutes goes to the abovementioned water-binding agents one before that the coal particles in a hot Lö- over activated coal with 30% Li Cl. . 108 minutes solution of the water-binding substances soaked and 10 can then be dried between 120 to 250 ° C. The invention results in an essential drying agent layer with an even better effect of technical progress. This consists in the fact that it cannot be achieved if the loading of the coal only takes place in a vacuum with the same filter size. The loading is so pre-filter is extended, but that even a hearing that the usable coal between 15 lengthening of the working capacity with lower filter 15 and 50%, preferably 30%. water-binding dimensions is achieved. The scaled-down and lightweight chemical contains. The design of the filter is very important To explain the opposite by the invention for the scope both in readiness and above the state of the art in the use of the filter in the event of a disaster in which reference is made to the following experiments: 20 the filter is used. Various desiccants were used as a filter _p Self-rescuer trained CO filters, whose Oxyda- claims = tion catalyst consists of hopcalite, introduced. In 1. Serving as protection against carbon oxide the filter vessels used for the experiments contain a respiratory filter, the one with oxidation catalysts, such as 140 cm ^{3 of} hopcalite were found. each 185 cm ^{3 of} 25 hopcalite is charged, the desiccant and Desiccant was connected upstream. if necessary, activated carbon is connected upstream so that The filters were on the artificial lung (pul- characterized by the fact that active- sizing) with an air flow of 30 1 / min., which is connected upstream with coal, which is known per se 16 g water / m ^{3 was} loaded and 0.1 volume percent CO was tested with 15 to 50%, preferably 30%, cal, up to the breakthrough of 0.01% CO. 30 is impregnated with cium and / or lithium halides. The resulting resistance times of the filter against the 2nd respiratory filter according to claim 1, characterized in-CO are a measure of the drying properties which indicates that-an overactivated various desiccant and thus for the decoal is used as the starting carbon. catching capacity of the filter. The filter tests showed the following results in 35 publications considered: with regard to the resistance time of the filter to Koh- German patents No. 820 892, 746 302, lenoxvd: 620 387. © 909 639/188 10.59