DE2525567C2 - Safety warning device - Google Patents

Description

The invention relates to a safety warning device according to the preamble of claim 1.

Such a device is already known (GB-PS 80 507).

Gas filter breathing devices typically have a filter canister covered with a granular sorbent material, such as e.g. B. activated carbon is filled. Such filter canisters are only suitable for highly toxic gases at a relatively low concentration of, for example, 1% or lower. For this reason, foal in front of the face bearing filter boxes for concentrations of toxic gases below 0, ^r> 's ό ι. At higher Koivjhtr, · lumen .lie l ^: ilterhuchsenfüllim>'^ ivac lie r in relatively κίι / ογ / ei' inter absurd the toxic the only part «· v. Whom ·: (hence in a retnebsunall lethal-poisonous 'Cιase leak. K, r · ■ tie ¹ ' gas mask wearer only determine the saturation of his filter canister when he notices the smell of gas when inhaling. However, he is already breathing in the poisonous gas , which can lead to permanent damage to health 5 or, in severe cases, even death. The wearer may not have enough time to leave the endangered area and go to a place where he can breathe fresh air Inhalation of the toxic gas may be very severe

ι ο can quickly lead to unconsciousness.

Many known filter systems of this type heat up very strong at high concentrations of toxic gases. This warming, which has the consequence that the Air inhaled by the gas mask wearer unange it is already used as a warning sign. at However, this warning sign may come too late for highly toxic gases. In addition, the carrier of the Gas mask in general has to direct all his attention to the execution of his duties, so that he consequently only notices the heating of the filter canister when it is already too late for the leave the endangered area. With filter canisters that are worn on the back of the gas mask wearer it is also essential for the wearer heavier, an increased temperature of the filter canister determine, especially if he is in a stressful situation.

There are many commonly used highly toxic gases that are difficult to determine to be a warning sign deliver. Such gases include the odorless and tasteless methyl bromide, which is used for rubber production and as a smoke gas in food production, as well as that in natural gas and im Hydrogen sulfide and coal mining occurring that found in coal combustion and as Preservatives and sulfur dioxide used as a smoke gas in the food industry.

Up to now there is no warning device which responds immediately to toxic gases released and which can be used under a wide variety of operating conditions such as e.g. B. can be used in chemical factories and plants . who are within listening distance of the warning device and would also be exposed to the toxic gases after a short time,

i <i if you do not leave the endangered area immediately. The invention has for its object to provide a corresponding one of the initially mentioned type safety warning device which acidic gases for a given dosing value is sensitized.

This object is achieved according to the invention by the features of claim 1.

The basic nitrogen-containing polymer of high electrical resistance has a predetermined value Dose value of acidic gases belonging to the group of acids

bO and Lewissituren belong, with the formation of a considerable reduction in the electrical resistance causing amount of electrolytic quaternary Amrrioniumsal '/ prevent reactive. A stick s'offiialuges l'o! \ Me'- therefore learns the l ■■; ■ Yervierlaehung the chemical • Va!.:; .. ii

Mwgln likci: c "/ iir advantageous further Ausgestai ■ iirig der ^! 'In ^1; ii, j' are in the A.iupr ehe;. ' to 7

specified.

The electrically conductive medium can consist of activated carbon, for example. The coating on the Electrode forms a barrier layer which provides electrical contact between the electrode and the medium If the electrical resistance between the electrodes is greatly reduced, the in Set off a signal device connected to the electrodes, an audio signal and / or an optical signal.

The container can be made of metal, for example in the form of a filter canister or a wire basket, and which form one of the two electrodes. If the safety warning device is arranged on a chemical filter breathing apparatus, not only the wearer of the breathing apparatus is unmistakably aware of dangerously high concentrations by the warning signal warned of toxic gases, but this fact can also be reported to other people, This is particularly important if the wearer is unconscious due to inhaled toxic gas should have become.

The invention is described below with reference to the exemplary embodiments shown in the drawings explained in more detail

F i g. 1 shows in the diagram from the front a man who carries a chemical filter respirator with such a safety warning device;

F i g. Fig. 2 shows, on a larger scale and partly in section, a two-electrode embodiment of the warning device;

F i g. 3 is a schematic circuit diagram of an optical and signaling device for the warning device which supplies acoustic signals;

F i g. 4 shows in section an embodiment of the safety warning device which has a single probe electrode;

F i g. 5 is a schematic illustration of a further exemplary embodiment of such a safety warning device with a single probe electrode.

The in Fig. 1 chemical filter respirator shown corresponds to a known face mask design such. B. that from Mine Safety Appliances Company of Pittsburg, Pa., V.St.A. manufactured type GMP.

Due to its limited capacity, the manufacturer recommends this device for breathing protection against toxic gases and vapors if their concentration does not exceed 0.5% by volume. The breathing device is shown here in connection with a safety warning device according to an exemplary embodiment of the invention. It consists of an electrically conductive filter canister 11 in the form of a copper-plated housing made of deep-drawn sheet steel in oval shape 12 with lower and upper cover 13 and 14 at the lower and upper end of the housing 12. The lower cover 13 has a screen opening 16 which when not in use, the filter canister can be closed in a sealed manner. In conventional breathing apparatus there is a filter (not shown here) at the bottom of the filter bushing for filtering out particulate matter such as e.g. B. toxic dust and the like. A pipe or hose gap 17 connects an opening in the top cover 14 with the face mask 18. The filter canister housing 12 allow; unhindered gas passage through the Filtcrliüchse so that accordingly the respiratory tract de ¹ carrier device ties ill.er the lüterbiicl ^ cm :: ί.τ Umgebuiigsiiifi combined seven.

As FIG. 2 shows, there is usually a sorption layer 19 inside the filter canister 11 z. B. from activated charcoal granulate activated charcoal absorbs many different toxic gases including 5 organic vapors such as B. alkyl halogens. aside from that the activated carbon serves as an electrically conductive medium for the safety warning device.

The conventional chemical filter respirator is used in part as an integral part of the

ίο Safety warning device used, for which the following parts are also provided: As Electrodes are, for example, two electrode probes 22 and 23 arranged at a mutual distance of copper embedded in the sorption layer 19 Electrodes are rigidly attached to the container housing 12 like z. B. the container side wall, with each electrode partially over the housing to the outside The probes are attached to the housing by means of an adhesive, load-bearing polymeric attachment by means of 20 such. B. an epoxy resin with electrical insulating properties attached The attachment means 20 encloses the probe electrodes via a short distance inside the filter canister, so that a short circuit between the electrodes and the filter Bush wall is excluded. The sorbent tel 19 is arranged in a layer and forms an electrically conductive path between the two Electrodes 22 and 23. As Fig.2 shows, the two probe electrodes are

so 22 and 23 each with a basic nitrogen containing polymer coating 24 provided. This coating 24 initially forms a barrier layer, which prevents the formation of an electrical connection between the electrodes via the activated carbon granulate, because this barrier layer has a high electrical resistance. In addition, the coating is thereby characterized in that it is able to react with a threshold value dcsis of certain toxic gases and a sufficiently large amount of electrolytic see quaternary ammonium salt groups form in the polymer, so that the electrical resistance is significantly reduced.

The polymer coating is applied to the electrodes by known coating methods, for example by immersing the probes in a solution of the polymer in a volatile solvent and then pulling them out, after which the solvent is allowed to evaporate. Polymers which are suitable for forming the coating 24 and which contain basic nitrogen are polyvinylpyridine, polyvinylamine and substituted amines, aminostyrene polymer, polyvinylpiperidine, aminated polymers and copolymers, as well as mixtures of the aforementioned polymers and with other polymers. Copolymers from monomers,

M contain the basic nitrogen and monomers that contain contain no basic nitrogen, should have a sufficiently high proportion of basic nitrogen containing monomers, so that the electrical resistance is reduced in the desired manner

ho can be. Suitable monomers for copolymerization to the aforementioned polymers are vinyl compounds, dienes such. ß. Butadiene, isoprene and Chloroprene, styrene. Λ Tvlnitril, Vin \ UiceUH. Methacrylic acid and Atliylacryia

l'ie with -.lent basic nitrogen of the coating 24 electronic quanc nare forming ammonium salts Highly toxic gases include organic and inorganic Sau:. ii. in wällr 'er I .ösiiru · Saurer. MIHpnHe (;; ιςρ

and alkyl halogens. The acids include hydrogen sulfide, hydrochloric acid, nitric acid, acetic acid, formic acid, chromic acid, chloroacetic acid, hydrogen selenide and hydrogen cyanide. The gases which form acids in aqueous solution are nitrogen oxides and sulfur · ■; dioxide. The alkyl halogens include ethyl or methyl chloride Λ -bromide.

The chemical. ~ · Η processes in the formation of quaternary Compounds from the aforementioned nitrogen compounds with toxic gases are known ·. Thereby the basic nitrogen atoms are contained Compounds converted into solid polyelectrolytes. The electrical conductivity of the electrolyte is depending on the type and concentration of the toxic gases, the humidity and the ambient r> temperature. It is also known that the presence of plasticizers such as / .. B. butyl lactate and dibuiyl tartrate in nitrogen compounds such. B. Poly-4-vinylpyridine this conversion into a polyelectrolyte favored. - '"

The initial ohmic resistance of the polymer coating on the electrode is very high and is, for example, more than 1 χ ΙΟ ¹⁰ ohms. After a sufficiently high number of quaternary ammonium groups has formed through contact with threshold levels - "j of toxic gas of the aforementioned type (e.g. at a concentration of 1000 PPM or 1 part to 10 ^J parts) the ohmic resistance drops by several orders of magnitude to, for example, 1 χ 10 * to 1 χ from 10 * ¹ Ohm. After the start of Quartemisierungsre- j ,, action occurs on the unexpected effect that the granular activated carbon particles adhered to the polymer surface, so that a good electrical contact between the activated carbon and the converted polymer electrolyte As explained further below, the circuit of the signaling device is closed at the lower ohmic resistance, with an acoustic and / or an optical signal being triggered the thickness of the polymer coating, the percentage of nitrogen in the polymer and the reactivity of the toxic gas.

The electrically conductive medium located in the filter sleeve between the two electrodes -r. is preferably made of carbon, as this is very effective and also inexpensive. In chemical filter respirators, therefore, activated carbon is generally used as a sorbent layer. Thus, only the two electrodes with the already vrvrhanHpnpn ^ r * rntir \ nccr ~ Hi / * ht in R # »riihnino cr ^ Krar ^ ht need to form an inexpensive warning device. -, - _oo ,

to become.

Surprisingly, it has been found that the quaternization of polyvinylpyridine is catalyzed by reaction with methyl bromide or methyl chloride gas in the presence of activated charcoal granules. This can be seen when comparing the speeds of the drop in electrical resistance with and without activated carbon

The signaling device, generally designated by the reference numeral 25 in the drawing, comprises an electrical circuit which is accommodated in the device housing 26. The circuit is electrically isolated from the housing the built-in electrode probes to the circuit. The signal device 25 can thus be removed from the electrodes, for example when the filter canister filling has been used up or has become unusable. By means of the signaling device, either an acoustic warning signal or a light signal can be emitted by a lamp 27, and both signals can also be generated simultaneously. The drop in resistance required to trigger the acoustic and / or optical alarm signal is obtained by converting the coating into an electrolytic, quaternary ammonium salt in the presence of the aforementioned toxic gases, by creating an electrical between the electrodes 22 and 23 through direct contact with the particles of the activated carbon layer 19 conductive bridge is formed.

A signal device 25 serving to generate an acoustic signal and an optical signal in the event of a dangerously high concentration of toxic gases is shown in FIG. 3 shown. The lines 28 and 29 are in the manner described above with the probe electrodes 22 b / w. 23 connected. If the electrically insulating barrier layer on an electrode is intact, the electrical resistance between lines 28 and 29 has a relatively high value and is, for example, more than 10 ° ohm Resistors R 4, R 5 and the high effective resistance between lines 28 and 29 are very low. The base of the transistor ζ) 3 is thus close to / u on the positive battery potential, so that the transistor is kept in the blocking state. The collector of the transistor Q 3 is connected to a light-emitting diode D I and an oscillator circuit, which consists of the transistors Q \ and Q 2, the resistors R 1, R 2 and R 3 and the capacitor C 1.

When the nitrogen in coating 24 forms a significant number of quaternary ammonium salt groups by reacting with a dangerously high concentration of toxic gases, the resistance between lines 28 and 29 drops. As soon as this resistance has reached a certain value of e.g. B. 20,000 ohms has dropped. the switching transistor Q 3 is turned on, so that the voltage at which serves as a visual warning light emitting diode D 1, and these lights. At the same time, the oscillator is activated via the resistor R 3 by means of the base of the transistor Q 1, so that it oscillates with a sound frequency, which by means of an electromechanical converter such. B. a loudspeaker connected between Ci and R 1 via line 30 is converted into an audible warning signal with a frequency of sound. If the user of the warning device should overlook the optical signal , he will in any case be warned by the acoustic signal

According to the embodiment shown in Figure 2 Both probe electrodes are each provided with a cover. It should be noted that only one of the two electrodes needs to be provided with an upper layer, as this already means a higher one Resistance is achieved which closes the electrical circuit between the electrodes In addition, the electrically insulating cover only needs in the area of the activated carbon, i.e. the to be provided electrically conductive medium.

In the embodiment shown in Figure 4 of the safety warning device, the electrodes are designed differently

again designed as in the embodiment according to FIG. The electrode 42 protrudes into the activated carbon layer 41 into it and is attached to the Filterbüchsc 40 by means of an electrically insulating fastening means 47 such as, for. B. held epoxy resin. The electrode 42 protrudes to the outside of the filter canister and is at its outer end with the circuit of Signal device connectable. The second electrode consists of the housing wall 43 of the filter sleeve 40. which consists of an electrically conductive metal, The signal device 44 is electrically connected to the housing wall 43 via an electrically conductive pin 45 The pin 45 is connected in the same way as a of the K-iden electrode probes 22 and 23 in the Embodiment according to FIG. 2 with the sound of the Signal device connected. A coating 46 of the type described above is on the Surface of the electrode 42 applied.

The Filierbüchse itself can serve to accommodate the signal device, including just a hole in the Γ Filter canister wall drilled and at least one Electrode is inserted into the activated carbon filling. Instead of activated charcoal you can of course also other electrically conductive media such as B. untreated carbon granules or metal particles use. With such substances, however, there is the disadvantage that the above-described No sorption function.

The one or both electrodes do not necessarily need to go through the filter canister side wall to be introduced, but can also be carried out at the point of the filter canister housing, it is only necessary that an electrically conductive medium such as. B. activated carbon between the Electrodes.

The safety warning device is applicable not only to chemical filter breathing apparatus with a filter canister to be worn in front of the face, but also to breathing apparatus of larger design which are carried on the chest or on the back. The possibility of generating an acoustic warning signal is particularly interesting when the filter canister is worn in front of the face or on the back, since it is generally difficult for the gas mask wearer in these designs to recognize an optical warning signal.

When the safety warning device is used in conjunction with a chemical filter breathing device, it warns the wearer effectively of dangerously high concentrations of toxic gases which exceed the capabilities of the breathing device.

The invention is an embodiment of compact design, which is generally the one shown in FIG The illustrated embodiment corresponds and is particularly good for use in limited space such as B. in exhaust ducts and the like. Is suitable. The device comprises a perforated one tubular-cylindrical container 50 made of an electrically conductive material such as. B. a Copper wire screen. The electrode 51 is embedded in the activated carbon layer 52 and electrically insulating fastening means 53 such. B. epoxy resin rigidly connected to the container 50. The container 50 forms the second electrode. The signaling device corresponds to the embodiment described above and is housed in a housing 54. Electrical leads 56 and 57 connect the electrode 51 and the Housing 54 with the circuit of the signaling device located in housing 54. The electrode 51 is provided with a coating 58 of the type described above.

The embodiment according to Figure 5 is suitable for installation in channels or pipelines through which a gas is passed. The signaling device is at a location remote from the channel or from the pipeline, e.g. B. arranged on a control panel. Since the container 50 consists of wire mesh, the electrode is in closer contact with the gas than in the event that it is located in a largely closed filter canister. In addition, the container can be made in very small dimensions (z. B. 2.5 cm in diameter and 15 cm in length), so that it can be accommodated in the smallest of spaces.

An independent embodiment of the safety warning device designed in the manner described above can be used wherever where there is a risk of toxic gas leakage and especially with the presence of People is to be expected, so that there is a serious risk to health or life. In this case, the warning device indicates a sudden escape or formation of toxic gases and warns people in the vicinity so that they leave the endangered area in good time can. Possible applications of the safety warning devices are in exhaust ducts, chemical Mills and plants, coal mines, paper and pulp mills, and the like. In these applications are Acoustic warning signals are particularly suitable. The warning device can also be installed in the driver's cab from Tank trucks are installed, which are used to transport toxic liquids and gases. When occurring

according to mine »ocr ciCKUiivncn uiici wai icici ixuu uuci if

Circuit and also by the type and thickness of the polymer coating.

The signal device does not need to be connected directly to the filter sleeve of a chemical filter breathing apparatus and can also be independent of such a can be used. In this case, of course, the face mask and the connection to the filter canister are not required. The filter sleeve of a breathing device can also be used without the same in connection with the Signal device are used. The container can also differ from the filter sleeve and for example, as shown in FIG. 5 be designed as described. The mode of operation of the safety warning device remains unchanged

In the case of FIG. 5 illustrated embodiment

goes, the driver is informed by the acoustic signal Warning device warned

Compared to using the warning device in conjunction with a chemical filter respirator is either a longer period of time or an higher concentration of toxic gases required. This is due to the fact that the breathing air together with the toxic gases in the breathing apparatus is quickly sucked through the Sorptionsschkht and heat is generated in the process. At a independent, fixed container, for example on the wall of a chemical plant is attached, there is a relatively small air movement, so that accordingly only one

low throughput of possibly existing toxic gases takes place through the device.

To reduce the response time of a stationary safety warning device in one A room with relatively little air movement can> the ambient air, which may contain toxic gas continuously circulated through the container by means of a fan, blower or pump will. Using a small four-cylinder electric pump, for example, an air throughput of 4 Achieve liters per minute through the container, with the toxic gas for example 1% of the gas-air mixture matters.

The safety warning device is extremely economical as it is used for filter canisters on conventional Gas masks such as B. the before. types manufactured by Mine Safety Appliances Company is. In the case of versions with two probe electrodes, these are attached to the wall of the filter canister and are electrical connected to the signaling device. For versions with a single probe electrode, this is in the Filter canister wall attached, the filter canister wall forming the other electrode at the same time. at both embodiments, d. H. with independent use of the warning device or also with Use of the same in conjunction with a chemical filter respirator allows the signaling device Attach directly to a filter canister or filter container. Also containers of other designs such as, for example, made of wire mesh in the above n> described execution are inexpensive to manufacture. The signaling device can after Alarm triggering of a warning signal removed from the used container and connected again is reused with an unused container will.

For a better understanding of the safety warning device according to the invention, this is described below illustrated with the aid of several illustrative exemplary embodiments.

example 1

Checking the suitability of the safety warning device to determine the presence of threshold concentrations of sulfur dioxide. The electrode "5 consisted of a conventional copper probe with was provided with a polyvinylpyridine coating. To do this, the probe was immersed in a chloroform solution, which 10 wt .-% polyvinylpyridine and 5 wt .-% lightly crosslinked, finely divided polyvinylpyridine so (of 0.150 mm particle size). The cross-linked particles were used to form a rough one Surface structure of the upper part. Activated carbon granulate with a grain size between 1.65 and 236 mm was in an electrically conductive metal cylinder in the form of a layer with a height of about 10 cm and The coated electrode probe was placed in the center with a diameter of about 24 cm embedded in the activated carbon layer The rough surface structure of the probe resulted in a good » physical contact between the top sheet and the granulate material

An air stream containing 1000 PPM anhydrous sulfur dioxide was fed at a rate of approximately 4 Liters of air per minute at room temperature passed through the bed in Table 1 below is the change in electrical resistance between the filter canister ground electrode and the Copper probe electrode shown in the activated carbon bed for two different series of experiments.

Table 1

Attempt 1 resistance Attempt 2 resistance Line (Ohm) Time (Ohm) (min) 1.0X 10 "' (min) 1.0X 10 "' 0.0 1, OX 10 "' 0.0 3, OX 10 ⁵ 4.0 2.0 X 10 ⁴ 3.0 9.0 X 10 * 4.5 1.3 X 10 " 5.0 2.0X 10 " 6.5 l, 0x 10 ⁴ 8.0 1.5 X 10 " 7.0 10.0

As can be seen from the table, the electrical resistance drops in the course of 3 to 10 minutes several orders of magnitude, which is due to the fact that by chemical reaction of the coating formed with the sulfur dioxide quaternary ammonium salts at the nitrogen points of the coating will.

Example 2

A copper probe was coated in polyvinylpyridine as described above and then from above into a commercially available gas mask filter canister of the GMA type containing activated carbon from Mine Safety Appliances Company so that they are embedded in the upper layer of activated carbon was. The filter canister served as a ground electrode for the electrical circuit.

Air containing 1000 PPM sulfur dioxide at 75% relative humidity was used in the respiratory flow rate of 25 liters of air per minute at room temperature passed through the filter canister. The ohmic one Resistance as a function of time is given in Table 2 below.

Table 2 Resistance (ohms) Time (min) 1.0X 10 '° 0.0 1.0X 10 '° 10.0 3.0 x 10 ⁷ 11.5 4.0 X 10 ⁶ 13.0 L5 x 10 " 15.0 1.0X 10 ⁶ 16.0 6.0 x 10 ⁵ 17.0 1.0 X 10 ⁵ 18.0 4.0 X 10 " 19.0 3.0 X 10 " 20.0

Example 3

A copper probe was coated by immersing it twice in a chloroform solution containing 10 % By weight of polyvinylpyridine and 10% by weight of crosslinked polyvinylpyridine particles having a particle size of 0.074 mm. In a container made of copper wire mesh with a diameter of 24 cm, a layer of Activated carbon granules with a particle size of 1.65 to

2.36 mm at a height of 12.7 cm. The coated probe was placed in the middle of the charcoal bed embedded. The copper probe electrode and the cylindrical copper wire mesh which is the other Electrode were made with the battery-powered, transistorized signaling device for optical and connected acoustic warning signals of the embodiment described above.

A stream of air containing 1.5% by weight of sulfur dioxide was passed at a rate of 15 liters per minute through a square duct with a ^{cross-sectional area of 929 cm 2} , in which the activated carbon bed was located. The ohmic resistance of the sensor probe was measured as a function of time and is given in Table 3 below.

Table 3 resistance Attempt 2 resistance Attempt I. (Ohm) Time (Ohm) Time 1.0X 10 ¹⁰ (min) 1.0X 10 '" (min) l, 0x 10 " 0.0 1.0X 10 ⁸ 0.0 3.0X 10 ⁵ 4.0 7.0 X 10 '' 3.0 1.0X 10 ⁵ 5.0 1.0X 10 ⁵ 4.0 2.0 X 10 " 6.0 6.0 x 10 * 5.0 7.0 2.0 X 10 " 6.0 8.0

Attempt I. Resistance Attempt 2 resistance Line (Ohm) Line (Ohm) (min) (min)

22.0
23.0
24.0
26.0

4.0 X \ 0 ^f
6.0 x 10 "
5.0x ΙΟ ³
2.0x 10 ^J.

25.0 26.0 26.5

5.0 x 10 "l, 0x 10 ⁵ 3.0 x 10 '

Example 5

A copper probe was coated with polyvinylpyridine in the manner described in Example 1, the crosslinked polyvinylpyridine particles corresponding to a proportion of 5% by weight. Any polymer coated The probe was placed in a breathing filter canister of the type GMC-SS-I from Mine Safety Appliances 2 «. Company used.

Room temperature air containing about 1% by volume of anhydrous hydrogen sulfide gas was passed through the filter canister at a breathing rate of about 30 liters per minute. The 2 ^r i ohmic resistance between the probe and the filter can mass was measured as a function of the exposure time.

The formed in the manner described above warning device has also been studied at the same flow rate of the gas mixture with a temperature of 110 ⁰ C. The ohmic resistance decreased from about 1. OxIO ⁹ ohms to about 4.0 OxIO ⁴ ohms after the bed was exposed to the hot, sulfur dioxide-containing air for about 2 minutes.

Example 4

A copper probe electrode was made accordingly Example 3, and then the polymer-coated probe was inserted from above into a commercially available gas mask filter canister from Mine Safety Appliances Company and inserted into the Upper activated carbon layer embedded The signaling device was attached to the as shown in the drawing Filter canister attached, but to the top cover of the same.

Air with 1.5% sulfur dioxide content and a relative humidity of 50% was in one Breathing flow rate of about 25 liters per minute at room temperature passed through the filter canister The ohmic resistance between the probe and the filter canister became a function of the time

Table 5 Resistance (ohms) Line (min) 1, OX 10 ¹⁰ 0.0 9.0 X 10 ⁸ 45.0 1, Ox 10 ⁵ 46.0 4.0 X 10 * 47.0 4.0 X 10 * 48.0 2.7 X 10 " 49.0 2.5 X 10 " 55.0 Example 6

A copper probe was coated with polyvinylpyridine in the manner described in Example 5 and from the side into a breathing filter canister with activated carbon layer of the type GMC-SS-I from Mine Safety Appliances Company used.

Air with 1% hydrogen sulfide content and 50% relative humidity was measured by a respiration flow rate of about 30 liters of ⁿ ro minute through the activated carbon in the filter canister passed through. The ohmic resistance as a function of time was measured and is shown in Table 6

measured and is in
specified.
Table 4 the following Table 4
60 Table 6 Resistance (ohms) Attempt 2
Time
(min) resistance
(Ohm)
65 Time (min) Attempt 1
Time resistance
(min) (Ohm) 0.0
20.0 1.0 X 10 '°
1.0 X 10 ¹⁰ 0.0
15.0
16.0
17.0
19.0
21.0 1.0 X 10 ¹⁰
9.0 X 10 "
8.0 X 10 *
6.5 X 10 *
5.0 X 10 *
1.0 X 10 * 0.0 1.0 X 10 ¹⁰
20.0 1.0 X 10 ¹⁰

13 14

Table 9 Example 7

Time (min) Resistance (ohms) 0.0 1, OX 10 '° 15.0 1, OX 10 '° 20.0 6.0 x 10 " 22.0 1.5 X 1O ⁵ 23.0 8.0 X 10 " 24.0 1, OX 10 " ? 5.0 3.3 X 10 '

A copper probe was with polyvinylamine in time (min) resistance (ohms)

10% solution in a volatile organic

Solvent, chloroiorm, coated and then in a s qq lOxiO ¹⁰ Filter canister of the design described in example 6 ''

inserted ¹⁸ '° ^{lfi x 10}

Air with 1% by volume hydrogen sulfide and 50% 23.0 2.0 x 10 ⁶

relative humidity was 24.0 2.0 x 10 ^{5 in a respiratory average}

of 30 liters per minute through the filter canister io ^^ q / n _{x 10} 4

passed through The probe resistance as a function of the ''

Time is given in Table 7 below. 28.0 3.0X10

τ u Μ -i Example 10

Table 7 ^v

A copper probe was immersed once in a coating solution containing 10% by weight of poly-4-vinylpyridine, 5% by weight of crosslinked polyvinylpyridine and 5% by weight % By weight of a high molecular weight polyester benzoate plasticizer in chloroform at room temperature The probe, which was coated with plasticizer, was inserted from above into a filter sleeve of the GMA type Mine Safety Appliances Company, which only contained activated carbon.

Air with 500 PPM methyl bromide at 70% relative humidity was used in a respiratory flow rate of about 20 Liters per Minu.c passed through the filter canister Example 8 measured the probe resistance as a function of time. The resistance values are in Table 10

specified.

A copper probe was made with a linear copolymer of 4-vinylpyridine and styrene in the ratio of 75 Coated by weight to 25% by weight in a chloroform solution at room temperature. The probe coated with poly-4-vinylpyridine-styrene was inserted into the activated carbon layer of the filter canister described in Example 6 used

Air with 1% by volume of hydrogen sulfide at 50% relative humidity was passed through the filter canister at a rate of 32 liters per minute. The probe resistance as a function of time is given in Table 8.

^Tabelie8 example 11

A polymer coating was produced with the coating solution given in Example 10, wherein however, the plasticizer has been omitted. Through a filter canister of the same type, 1% by volume Methyl bromide in a higher respiratory flow rate of 32 liters per minute passed through. During the As the gas-air mixture was passed through, the filter sleeve was knocked lightly every now and then, so as to make one to ensure good electrical contact between the activated carbon granulate and the probe. Of the Resistance as a function of time is shown in Table 11 below

Example 9

Using the same experimental setup as in Example 8, the polymer coating was produced in such a way that t * a copper probe was coated in a 10% strength by weight solution of linear poly-paraaminostyrene in chloroform at room temperature. Air with 1 vol .-% of hydrogen sulfide at 50% relative humidity was passed in a respiration flow rate of about 30 liters h ^r> per minute through the filter canister. The probe resistance as a function of time is given in Table 9 below.

Table 10 Resistance (ohms) Time (min) 1.0X 10 '" 0.0 l, 0x 10 '" 15.0 3.0X 10 ⁸ 16.0 l, 0x 10 " 18.0 l, 0x 10 ⁷ 25.0 7.5 x 10 " 30.0

Time (min) Resistance (ohms) 0.0 1.0X 10 '" 16.0 1.0X 10 '" 17.0 80X 10 ^s 20.0 3.0 X 10 * 22.0 4.0 X 10 " 24.0 1.9 X 10 " 28.0 0.9 x 10 "

Table 11 Resistance (Ohml /.eil (min) 1, OX 10 '" 0.0 1, OX 10 " 10.0 LOx 10 " 14.0 1.5 x 10 " 19.0 1.0 χ io ^J 25.0 4.0 XIO ¹ 28.0

Example 12 Example 13

A copper probe was immersed in a chloroform solution containing 10% linear-4-poly-vinylpyridine, however contained no plasticizer. The coated probe was inserted from above into a respirator filter canister of the type GMA from Mine Safety Appliances Company used in the activated carbon filling, the Container wall was used as a ground electrode.

Air with 2% methyl chloride was at a breathing rate of about 25 liters per minute through the Filter canister passed through. This was gently bumped to ensure good electrical contact between the Aktivkohteteilchen and the polymer coating to guarantee. The ohmic resistance as a function of time is given in Table 12 below.

Table 12 Resistance (ohms) Time (min) 1.0X 10 "' 0.0 l, 0x 10 " 15.0 4.0 x 10 " 21.0 3.0 x 10 " 26.0 1.0X 10 * 30.0 Example 14

Table 13

In this experiment, that in Example 11 The filter canister described was used, but not only was the copper probe with the polymer coating coated, but also a copper wire mesh intermediate layer, which served to create different activated carbon sorption layers inside the filter canister to separate from each other. The length of the wire mesh was 16.5 cm and the width 83 cm. The polymer-coated wire mesh was wrapped around its periphery with electrically insulating cotton, to avoid a short circuit to the metal filter sleeve a

When a gas mixture was passed through the system as described above, corresponding Results obtained, however, with the resistance values somewhat higher throughout the experiment lay.

Time (days)

Resistance (ohms)

A copper probe was coated with polyvinylpyridine in the manner described in Example 1. The coated probe was laterally inserted into the wall of a breathing device filter canister filled with activated charcoal of the type GMA from Mine Safety Appliances Company.

Air with 1 vol .-% methylbnMiiid and 50% relative Moisture was then dui'chgelitet through the filter canister for about 20 minutes.

The ohmic resistance of the probe over the course of three days following the experiment is in the Table 13 below.

0 1.0 x 10 ¹⁰ 1 9.0 x 10 ⁶ 2 2.0 x 10 ⁶ 3 5.0 x 10 ⁵

20th

25th

JO

Y-, This experiment showed that the resistance of the probe decreases with the storage time of the filter canister, ie the dwell time of the methyl bromide absorbed by the activated carbon. The methyl bromide tends to desorption and migrates through the activated carbon layer inside the filter canister.

Example 15

A probe coated with polyvinylpyridine was embedded in an activated carbon layer as described in Example 1. In successive experiments, the probe was exposed to high concentrations of sulfur dioxide, methyl bromide, ethyl bromide and hydrogen sulfide in moist air of about 50% relative humidity at room temperature.In all cases, the electrical resistance fell within about 6 minutes by several orders of magnitude from 10 ¹⁰ ohms to about 10 ³ ohms.

When the same experiments were repeated with vapors heated to 80 ° C, the resistance still fell faster. It is believed that this is due to an acceleration of the quaternization reaction at higher Temperatures is due.

The aforementioned test results were also obtained at the same high concentration when the Polymer coating instead of polyvinylpyridine from polyvinylamines, copolymers of 4-vinyl-pyridine and -styrene, poly-para-aminostyrene and poly-4-vinyl-piperidine duration.

Example 16

An electrode probe of the design described in Example 1 was used for several experiments, their polymer coating made of polyvinylpyridine, poly-4-aminostyrene or polyvinylamine existed. The gas passed through contained 0.5 to 2.5% by volume of a gaseous one Acid in air at 50% relative humidity. The acids were formic acid, chromic acid, acetic acid, Chloroacetic acid, hydrogen cyanide, hydrogen fluoride and hydrochloric acid.

In all cases, the electrical resistance dropped after several minutes at room temperature at least 2 to 3 orders of magnitude (i.e. to at least 1/100 to 1/1000). This became a rapid quarternization reaction demonstrated, which shows that the aforementioned coatings also for Use for warning against the presence of the aforementioned acid gases.

For this purpose I sheet drawings

Claims (7)

Patent claims: 1. Safety warning device to indicate the presence of a predetermined dose value certain toxic gases with a container, two spaced apart Electrodes, a coating formed on at least one electrode, the electrical resistance of which is considerably reduced by the action of the toxic gases to be detected, and one connected in series with the electrodes and reducing the electrical resistance Signaling device serving to generate a signal, characterized in that the electrically conductive coating made of a basic nitrogen-containing polymer electrical resistance. ?. Safety warning device according to claim 1, characterized in that the polymer is selected from the group consisting of polyvinylpyridine, polyvinylamine and substituted amines, Aminostyrene polymers, polyvinylpiperidine, as well as copolymers, mixtures thereof and mixtures with other monomers. 3. Safety warning device according to claim 1 or 2, characterized in that the electrical conductive medium (19, 41, 52) consists of a granulate layer located in the container. 4. Safety warning device according to claim 3, characterized in that the medium consists of Activated carbon granulate consists 5. Safety warning device according to claim 1, characterized in that the electrode (22, 42, 51) is designed as a probe which is embedded in the electrically conductive medium. 6. Safety warning device according to one of claims 1 to 4, characterized in that the one electrode is embedded in the electrically conductive medium and the other electrode is made of a Wire mesh. 7. Safety warning device according to one of claims 1 to 4, characterized in that both electrodes (22,23) designed as probes and at a mutual distance into the electrical conductive medium are embedded.