A wide variety of industrial gas products can be categorized into two main types: general industrial gases and special gases. General industrial gases have high production and sales volumes but do not require high purity. Special gases, although with lower production and sales, have stringent requirements for purity or composition, allowable content of harmful impurities, and product packaging and storage, making them high-tech, high-value-added products. Typically, special gases can be divided into three categories: high-purity or pure gases, standard calibration gases, and mixed gases with specific compositions. As a crucial raw material for modern industry, gas products have a broad range of applications, including metallurgy, steel, petroleum, chemicals, machinery, electronics, glass, ceramics, building materials, construction, and food processing, where both common and special gases are extensively used.
The applications of industrial gases involve the concept of an ideal gas, which assumes that gas molecules have no intermolecular forces and no volume. When the actual pressure of the gas is low and the average distance between molecules is large, the volume of the gas molecules themselves can be disregarded. Additionally, if the temperature is not too low, the average kinetic energy of the molecules is high, and the attractive forces between them are negligible compared to this. In such cases, the behavior of real gases is very similar to that of ideal gases, and they can be treated as ideal gases. The following content discusses ideal gases, but it should be remembered that real gases differ from them. The conclusions drawn from discussions using ideal gases only apply to real gases under conditions of moderate pressure and temperature.
Industrial mixed gases are a new variety that has emerged in the past two decades, with a wide range of applications, but there is no unified standard for their classification. Industrial mixed gases are divided into two categories: naturally synthesized and pure product formulations. They can be categorized as gaseous mixed gases, liquid mixed gases, and Shenqi gas-liquid mixed gases based on their state. According to their main hazardous components, they are generally divided into flammable mixed gases, spontaneous combustion mixed gases, highly toxic mixed gases, and corrosive mixed gases. The newly emerged gas-liquid mixed gases, when used for cutting, demonstrate significant advantages over other mixed gases in terms of stability, mixing degree, and application effectiveness.
Common physical properties of industrial gases can be summarized as compressibility and expansibility. When a certain amount of gas is subjected to increasing pressure while the temperature remains relatively constant, its volume decreases. If pressure continues to rise, the gas can be compressed into a liquid, demonstrating its compressibility. Industrial gases are typically stored in cylinders in a compressed or liquefied state. Upon exposure to light or heat, the temperature of the gas rises, causing an intensification of thermal motion between molecules, leading to an increase in volume. If confined within a container, the higher the temperature to which the gas is exposed, the greater the pressure it will exert upon expansion, illustrating its heat-induced expansibility. Compressed and liquefied gases stored in containers are prone to expansion when exposed to high temperatures or sunlight, which can generate significant pressure. If this pressure exceeds the container's strength, it can result in injury. Therefore, industrial gases are inherently hazardous.
