Basic principles of protection against the hottest

Basic principle of explosion protection

Zhuhai Sansi Measuring Instrument Co., Ltd; Shao's LX-A rubber hardness tester has a wide variety of combustibles used in industrial production, a large number, and the production process is complex, so it is necessary to take various corresponding protective measures according to different conditions. But in general, the three basic conditions to prevent chemical explosion exist at the same time, which is the basic theory to prevent chemical explosion of combustible substances. From the perspective of the formation of the destructive power of explosion, explosion generally requires five conditions: (1) combustible substances that provide energy (release source); (2) . combustion supporting agent (oxidant) for auxiliary combustion; (3) . uniform mixing of combustible materials and combustion supporting agents; (4) The mixture is placed in a relatively closed space (enclosure); (5) Ignition source with sufficient energy. These five conditions can be vividly described by explosive Pentagon (see Figure). When these five conditions occur at the same time, the destructive power of explosion appears. Explosion proof technology is to take corresponding technical and management measures according to the explosion pentagon to achieve the purpose of preventing accidents. Figure explosion destructive force Pentagon 1. Control of combustible concentration explosion intensity is closely related to the concentration of explosive mixture (see Figure). In the range of concentration C, the relationship between explosion intensity and concentration is similar to the sine curve of positive half cycle. If the concentration exceeds this range, the explosion cannot occur. The theoretical explanation of this phenomenon is that when the concentration of explosive mixture is close to the chemical equivalent concentration of oxidation reaction, the explosive mixture can burn completely, with the maximum heat release and explosion intensity, as shown in point B in Figure 1-2. In the figure, the explosion intensity is represented by the explosion BASF said that ucrete polymer can adsorb the uremic toxin creatinine urethane contained in the blood of patients with renal failure. The concrete system adopts the industrial floor standard explosion overpressure P. the explosion overpressure is the pressure increment generated by the explosion of explosive mixture under normal pressure. If the concentration changes from point B to the low value, as the number of combustibles decreases, the calorific value decreases accordingly, the temperature of combustion exhaust gas is also lower than the normal point, and the pressure increment P caused by temperature rise (the difference between gas temperature and room temperature) also decreases. When the concentration is low to point a, the calorific value of combustible substances is too low to maintain the minimum temperature required for flame propagation in the mixture, so the mixture will not be ignited. If the concentration changes from the ^ point to the high value, the number of combustible substances will certainly increase, but at this time, the concentration of oxygen supporting combustion is lower than the chemical equivalent value, which cannot meet the needs of complete combustion of the mixture. The calorific value of the mixture will be lower than that of the chemical equivalent concentration, and the pressure increment P will also be reduced. Therefore, in section BC, the explosion intensity will weaken with the increase of the concentration of combustible gas. When reaching the concentration of point C, due to the lack of combustion supporting oxygen, The combustion calorific value of the mixture is also too low to maintain the minimum temperature required for flame propagation in the mixture, so the mixture cannot be ignited. Here, a and C are two critical points. The mixture can explode in the concentration range from a to C, and the mixture cannot explode when its concentration is less than a or greater than C. point a is called the lower explosion limit concentration, and point C is called the upper explosion limit concentration. Figure relationship between explosion pressure P and combustible concentration D. therefore, it can be determined by combustible concentration