Safety Technology Exchange Edition: Daily Question (2016.5.3)

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bg10.png Type: Fill-in-the-blank question. Question: [Safety Technology] The safe distance between acetylene cylinders and oxygen cylinders refers to the fact that, during construction work, oxygen cylinders and acetylene cylinders must be kept at a distance of ____ meters from the point where welding or burning takes place; moreover, the distance between an oxygen cylinder and an acetylene cylinder should be at least ____ meters. Answer: 10 ； 5. Reason: During the production process, acetylene cylinders (hereinafter referred to as acetylene tanks) and oxygen cylinders are widely used in welding and cutting, and are often used simultaneously. Oxygen acts as a combustion aid, while acetylene is a flammable gas. Both types of cylinders are stored in portable pressure vessels. During use, various problems arise to varying degrees, such as the acetylene tank and oxygen cylinder being placed in the same location without sufficient safety distance; the oxygen cylinder coming into contact with oils; the acetylene tank being rolled horizontally and then used without being set upright; the surface temperature of the acetylene tank exceeding 40°C, especially during outdoor operations in summer without any protection; and the oxygen and acetylene cylinders not having the required residual pressure. These problems have led to some casualties. Since it is dissolved acetylene, propane is present in the gas cylinder; if the inclination angle is below 30 degrees, opening the valve (during use) may cause propane to leak out and mix with air, forming an explosive mixture. The explosive limit is 2.55%–12.8% (by volume). Oxygen cylinders contain high-pressure oxygen, which presents physical and chemical safety hazards: Physical hazard: When oxygen is compressed and the pressure increases, it tends to reach equilibrium with the surrounding ambient pressure; the greater the pressure difference between it and the ambient pressure, the stronger this tendency becomes. When a very large pressure difference rapidly reaches this equilibrium over a considerable distance in an extremely short time, what is commonly referred to as a \"blowout\" occurs. If this equilibrium is reached over a relatively long period of time through smaller pores, a \"jet\" is formed. Both can lead to serious consequences. Chemical factors. Since oxygen is an oxidizing agent, it can cause intense combustion as soon as it comes into contact with flammable materials and an ignition source, potentially leading to explosive fires. 1. Article 50 of the \"Safety Inspection Regulations for Dissolved Acetylene Cylinders\" issued by the Labor Ministry under document No. 81 Guozi 10, which outlines the rules for using acetylene cylinders, states that \"when using both oxygen cylinders and acetylene cylinders simultaneously, it is necessary to avoid placing them together; the distance from open flames should generally be at least 10 meters.\" However, the distance between the two cylinders is not specified in this regulation. 2. GB9448-1999 \"Safety in Welding and Cutting\": When in use, the distance from open flames should be more than 10 meters; however, the distance required between oxygen and acetylene cylinders is not specified as clearly in China. 3. According to Standard GB26164.1-2010, which was issued on January 14, 2011 and came into effect on December 1, 2011, Article 14.4.9 of the \"Safety Regulations for Electric Power Work (Thermal and Mechanical Systems)\” stipulates that: \"Oxygen cylinders and acetylene cylinders in use should be placed vertically and secured; the distance between an oxygen cylinder and an acetylene cylinder must be at least 5 meters.\" " 4. Article 2 of the \"Safety Operating Procedures for Gas Welding (Cutting)\\" states that \"oxygen cylinders and acetylene cylinders should be stored separately, with a distance of at least 5 meters between them.\" "