FI78172C - SAETT ATT TILLSAETTA LUKTAEMNE TILL OXYGENGAS. - Google Patents

Description

1 78172

It is an object of the present invention to provide a method for improving the method for adding perfumes to oxygen gas delivered to a site of use to draw the attention of the environment to the high risk of fire or explosion in the event of unintentional enrichment of oxygen in the air; this is achieved by eliminating the on-site handling of toxic substances and eliminating the risk of explosion associated with the addition of perfume.

More and more attention is being paid to the dangers of using oxygen. This is primarily a fire hazard due to the enrichment of clothing or air with oxygen in enclosed spaces. Several serious accidents have also occurred during the year, for example when working with leaking welding and cutting torches and working on gas pipelines in cramped or poorly ventilated spaces. The increasing oxygen content of the air facilitates ignition and makes combustion faster and hotter.

The physical explanation is that when the normal oxygen content of the air rises to 21-56%, the ignition risks of many materials are greatly increased, and combustion occurs very strongly. When the oxygen content of the air rises to 30%, ignition occurs very easily and there may be enough inductively generated electrical sparks. The combustion of many materials, such as fabric, is essentially explosive. This is because oxygen is most often present throughout the volume of the fabric so that combustion occurs simultaneously throughout. This phenomenon also makes the fire very difficult to extinguish.

For example, some shipyards have attempted to reduce the risk of oxygen enrichment through oxygen scenting. Special 2 78172 Dosing devices are connected to the yard's piping, and a malodorous sulfur compound is introduced into the oxygen. This technique has long been used to perfume propane, natural gas and city gas.

However, the advantages and disadvantages of oxygen scenting have been debated. Advocates for oxygen scent include professional representatives of companies who are actively pursuing the issue with a view to increasing workplace safety. Disadvantages include safety concerns with the use of available dosing equipment. These work by dispensing a concentrated fragrance, which is highly toxic, and ask whether one can be trusted that the dose will not grow too high. Another disadvantage is that the perfume-oxygen mixture is explosive at certain concentrations.

There are also certain requirements for the perfume itself.

It must have a strong and obvious smell. It must remain unchanged for long periods of time and it must be flammable. After combustion, the combustion product must be odorless. It must not react with oxygen and must not adversely affect welding and cutting processes. It must, of course, be: available enough.

Dimethyl sulfide has heretofore been used as a suitable fragrance.

- This fragrance is conducted at the point of oxygen application. Oxygen is usually distributed to the user in two ways, either in high pressure tanks or directly through low pressure piping. So far, only low-pressure oxygen has been able to be perfumed. During the perfuming of oxygen, there is a danger of poison when handling the perfume, and in addition to this, mixing the perfume with oxygen creates a process that can cause an explosion hazard. Thus, there are two dangerous situations: the risk of toxicity when handling perfume and the risk of explosion when perfuming oxygen. This has led to an inverse scenting method according to the invention, the purpose of which is to reduce the risk of fire and explosion which exists in the event of a leak in the form of unintentional oxygen enrichment.

3,78172

The object of the present invention is to eliminate the treatment of the fragrance at the place of use and to enable the smelling of both low and high pressure oxygen. The invention is characterized in that in specially suitable spaces a concentrated gas, a so-called model gas, is produced by adding a perfume having a concentration of 1000-10000 ppm to pure oxygen gas, and the resulting sample gas is added to the oxygen gas in a space separate from the above spaces. the amount of perfume in the working gas has a concentration of 5-50 ppm.

The invention is further characterized in that when distributing oxygen to the user through a direct low-pressure pipeline, the sample gas is added to the oxygen before it is introduced into the pipe, wherein the product in the pipe contains a gas mixture of oxygen and perfume. In addition, the invention is characterized in that when distributing oxygen gas to the user in high-pressure tanks, the sample gas is introduced into the tank before the tank is filled with compressed oxygen gas, whereby the tank contains a gas mixture of oxygen and perfume.

The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 shows a schematic diagram of a distribution system according to the invention and Figure 2 shows a plant in which perfume is added to oxygen.

The plant includes a tank 1 located outside the building, which contains liquid oxygen with an oxygen pressure of about 8 bar. Oxygen is led from the tank through a low-pressure evaporator 2 to a gas mixer 5 located in the filling building. The gas pressure is now about 12 bar. Also connected to the gas mixer is a tank 7 containing a so-called sample gas and a pressure equalization tank 6. The sample gas in the tank 7 is manufactured in a special plant specially built for the handling of toxic and explosive substances. The sample gas is a concentrated gas mixture in which a fragrance with a concentration of 1000-10000 ppm 4 78172 is added to oxygen gas. In the gas mixer 5, so much sample gas is added to the oxygen gas that the operating gas supplied to the user via the pipeline 10 contains a fragrance with a concentration of about 5-50 ppm.

From the tank 1 containing liquid oxygen, oxygen is led through a pipe to a high-pressure pump 3. From here, the gas is led through a heating plant 4 to a mixing panel 8. The gas pressure is now about 200 bar. In addition, a pressure vessel 9 and a sample gas tank 7 are connected to the mixer panel. After the mixer panel, the gas is a compressed gas containing a perfume having a concentration of 5-50 ppm. The compressed gas is led through filling ramps 11 and connectors 12 to oxygen tanks. The high pressure vessels are then transported to the user.

Figure 2 shows a sketch of a plant in which the model gas is added partly to low pressure (approx. 12 bar) and partly to high pressure (approx. 200 bar) oxygen. The symbols are the same as in the diagram of Figure 1. The liquid oxygen tank 1, the low-pressure evaporator 2, the pump 3 and the heating device 4 are all located outside the building to which the sample gas is led. Model gas tanks 7 are located in a special room in the building. Likewise, the pressure equalization tanks 6 and the pressure vessels 9 are placed in a special room. The gas mixer 5 and the mixer panel 8 are located in the room where the high-pressure filling of the oxygen tanks takes place by means of filling ramps 11 and connectors 12. A line 10 is drawn from the gas mixer 5 to distribute the perfumed low pressure oxygen to the user. The gas mixer 5 and the control panel 8 for mixing the sample gas are already known of the type.

With the method described above, on-site safety has been significantly increased and on-site handling of toxic and explosive perfumes has been eliminated. The tanks produce both low- and high-pressure perfumed oxygen gas with a guaranteed fragrance content. Thus, all types of oxygen gases can be perfumed.

5,78172

As a suitable perfume added to oxygen gas, an organic sulfur compound can be mentioned. Of these, the aforementioned dimethyl sulfide is best suited for oxygen scenting. This is because dimethyl sulfide has a low Odor Threshold, high vapor pressure, it does not react with 200 bar oxygen at normal temperature, it is non-toxic at low concentrations and its combustion product is odorless. Dimethyl sulfide at a concentration of 5-50 ppm is malodorous, but does not cause disease-like nuisances or other damage, does not explode on contact with oxygen, and has been shown by long-term experiments to remain unchanged both qualitatively and quantitatively and does not cause corrosion of gas tanks. Indeed, dimethyl sulfide has been used as a fragrance in the past, but not at the same degrees of concentration and has not been derived in the ways described in the description of the invention above.

Claims (5)

6 78172 Claims. A method for adding perfume to an oxygen gas delivered to a site to draw environmental attention to the risk of explosion after oxygen has been enriched so as to eliminate the handling of toxic substances at the site and minimize the risk of explosion due to the addition of perfume, characterized in that that a perfume having a concentration of 1000-1000 0 ppm is added to pure oxygen gas; the formed sample gas is added to the oxygen gas distributed to the user in a space <5, 8) separate from the above-mentioned space (7) so that the concentration of the fragrance in the working gas is 5-50 ppm. A method according to claim 1, wherein the oxygen gas is distributed to the user via a low pressure pipeline <10>, characterized in that the sample gas is added to the oxygen gas before it is introduced into the pipeline <10), the line containing a gas mixture containing gas and perfume. A method according to claim 1, wherein the oxygen gas is distributed <11, 12) to the user in a high pressure tank, characterized in that the sample gas is added to the tank <8) before the tank is filled with <1, 3, 4) compressed oxygen gas so that the tank <8> has a gas mixture containing oxygen gas and perfume. Process according to Claim 1, characterized in that the perfume consists of an organic sulfur compound. Process according to Claim 4, characterized in that the organosulfur compound is dimethyl sulfide.