Basic knowledge of Oxygen safety

Oxygen has very strong oxidizability and combustion supporting property. The ignition point of combustible materials in pure oxygen will be reduced, and the oxygen pipeline system itself has high safety requirements. Air conditioning companies use a large amount of oxygen and have many points, which are widely distributed, and the pipe network laying is complex, involving the first to third floors of 502 plant and 504 plant, which is relatively dangerous. In order to let the majority of employees fully grasp the basic knowledge of oxygen, it will be more conducive to the safe management and use of oxygen in our company, and escort the future development and growth of the air conditioning company. The textbook of this chapter is specially compiled.

Section 1 Properties and manufacture of oxygen

1 Properties of oxygen

Oxygen is one of the most widely distributed elements in nature, which is the material that organisms rely on for survival. It exists in the air as a free state and contains 20.93% oxygen by volume. Oxygen also exists in water, minerals and all animals and plants in a combined state. Oxygen is colorless, transparent, tasteless and odorless gas at normal temperature and pressure, which is slightly heavier than air. Under atmospheric pressure, when the temperature is - 182.96 ℃, the oxygen condenses into sky blue, transparent and easy flowing liquid; when the temperature is - 218.4 ℃, it condenses into blue solid crystal.

The chemical property of oxygen is very active. It is a strong oxidant and combustion supporting agent. It can combine with other substances to form oxides except gold, silver and inert gases such as helium, neon, argon, krypton and xenon. The intensity of the oxidation reaction depends on the concentration and pressure of oxygen. If the oxidation reaction is carried out in pure oxygen, the process is very violent and a lot of heat is released at the same time. (for example, the metal reacts in oxygen, if the purity and pressure of oxygen are increased, the oxidation reaction will be significantly intensified, and the ignition point of metal will decrease with the increase of oxygen pressure). When oxygen is mixed with combustible gases (acetylene, hydrogen, methane, etc.) in a certain proportion, it will explode in case of fire. After oxygen is compressed, in the process of transportation, if there are grease, iron oxide chips or small particles of combustibles (pulverized coal, carbon particles or organic fibers), with the air flow movement, there will be friction and impact with the pipe wall or the body, which will produce a lot of friction heat, leading to the combustion of pipes and machines. Or because of the sudden opening of the valve in the pipeline, the temperature of the gas behind the valve is close to the adiabatic compression, which makes the pipeline or valve burn. Clothing and other organic textiles saturated with oxygen will catch fire immediately when they come into contact with the fire. When the porous organic matter impregnated with liquid oxygen is ignited or impacted by a certain force, an explosion accident will occur. After long-term weak discharge, liquid oxygen turns into dark blue liquid ozone, which is easy to explode.

Oxygen molecules can be magnetized and attracted by the magnetic pole. According to the characteristics of oxygen, a magnetic oxygen analyzer can be made to analyze the purity of oxygen.

Under normal pressure, when the concentration of oxygen exceeds 40%, oxygen poisoning may occur. When 40% - 60% oxygen is inhaled, there will be discomfort and light cough behind the sternum, and then chest tightness, burning sensation behind the sternum, dyspnea, and cough aggravation; when severely punished, there will be pulmonary edema, and even respiratory distress syndrome. When the concentration of inhaled oxygen was more than 80%, facial muscle twitch, pale complexion, vertigo, tachycardia, collapse, and then severe convulsions, coma, respiratory failure and death occurred. Long term exposure to oxygen partial pressure of 60-100kpa (equivalent to about 40% of the concentration of inhaled oxygen) can cause eye damage and blindness in severe cases. It is suggested that emergency treatment personnel should wear self-contained positive pressure respirator and general work clothes. Avoid contact with combustibles or combustibles. Cut off the leakage source as much as possible. Reasonable ventilation, strengthen diffusion.

Oxygen is widely used in industrial production, such as liquid oxygen in the national defense industry can be used as rocket combustion supporting agent; moreover, cutting and welding in the mechanical industry; oxygen steelmaking, steel rolling and non-ferrous metal smelting in the metallurgical industry; as well as medical and deep-water operations need to use a lot of oxygen.