Classification of explosive substances
China has the same requirements as the IEC standard to classify explosive substances into three categories (referred to as "Group" in English):
- Type I: Mine Mine;
- Class Ⅱ: Explosive gas mixture (containing vapor and mist);
- Class III: Explosive dust and fibers.
- North American countries classify explosive substances into three categories (English is represented by "Class", which can be translated as "grade"):
- Class I: Explosive gas;
- ClassⅡ: Explosive dust;
- Class III: Fiber.
The Class I explosive substances referred to in our country refer to mine methane, commonly known as "gas" gas. The main cause of coal mine explosion is that the concentration of methane gas in the mine has reached the explosion limit, and the explosion caused by the ignition source. Due to the special underground environment of coal mines, methane is specifically classified as Class I. Mine explosion-proof electrical equipment is mainly to prevent methane explosion, other flammable gases are very little in the mine, and no special consideration is given to electrical explosion-proof performance. Therefore, mine explosion-proof electrical equipment is not applicable in other hazardous locations.
Class II explosive substances include explosive gases and explosive vapors. The so-called explosive gas refers to a combustible gas, that is, a mixture of gases when hydrogen, carbon monoxide, ethylene oxide, etc. are mixed with air and the concentration reaches the explosive limit. The so-called explosive vapor refers to a gas mixture or mist with the vapor or fine droplets of a flammable liquid (acetone, gasoline, etc.) mixed with air to reach the explosive limit.
It should be pointed out that gases and vapors that can automatically explode when in contact with each other are not included in this list. For example, explosive gases formed by fluorine and hydrogen, chlorine and acetylene, ozone and ethanol vapor are not classified as type II, because the reason for the explosion caused by the encounter of these explosive gases is different from the foregoing.
Class III explosive substances include explosive dust and explosive fibers. It refers to a mixture of dust and fibers that can produce an explosion, including combustible dust or fibers (such as cotton fibers) that are mixed with air to reach the explosive limit. Because conductive dust has greater danger, explosive dust is divided into conductive dust (such as aluminum powder) and non-conductive dust (such as starch) according to its conductive properties.
Explosive dust (or fiber) is very powerful when it explodes, and electrical equipment needs to have sufficient strength so as not to be damaged. Therefore, explosives do not fall into the category of explosive dust and fibers. Electrical equipment for explosive dust environments is not suitable for explosive production sites. Mystone 's explosion-proof products are SC910N and SC910 combustible gas detectors. Different gases can be used for gas detection by replacing sensors.