Structure and principle of flame arresters

　A flame arrester is designed and manufactured based on the principle that a flame is extinguished due to heat loss when it passes through the narrow pores of a heat conductor.

Inside the flame arrester there is a fine mesh of steel wires. When the flame reaches this area, heat is transferred to the wires; due to their rapid heat dissipation ability and the way they disperse the flame, the temperature drops below its ignition point, thus achieving the effect of extinguishing the flame. It’s just a simple opinion, haha

A flame arrester mainly consists of a housing and a filter element. The housing must have sufficient strength to withstand the shock pressure generated by an explosion. The filter element is the main component that prevents the spread of flames; the commonly used types are metal mesh filters and corrugated filters. Metal mesh filters are composed of multiple layers of stainless steel or copper mesh with a diameter of 0.23~0.315 mm, stacked on top of each other. Currently, fire arrestors used in China typically employ metal mesh with a mesh size of 16–22, consisting of 4–12 layers. 　　Wavy filter elements are supported by stainless steel, copper-nickel alloys, aluminum, or aluminum alloys. Wavy-type flame arresters can contain the intense flames of deflagration, withstand corresponding mechanical and thermal stresses, have low flow resistance, and are easy to clean and replace. Regarding the working principle of flame arresters, there are currently two main views: one is based on heat transfer, and the other is based on the wall effect. 1 Heat transfer One of the necessary conditions for combustion is to reach a certain temperature, namely the ignition point. Below the ignition point, combustion will stop. According to this principle, the spread of flames can be prevented by lowering the temperature of the burning material below its ignition point. When the flame passes through the many small channels of the flame arrestor, it becomes several small flames. When designing the flame-arresting elements inside a flame arrester, it is necessary to maximize the contact area between the small flames and the wall of the channels, thereby enhancing heat transfer and reducing the flame temperature below its ignition point, and so preventing the spread of the flame. 2 Wall Effect Combustion and explosion are not direct reactions between molecules; rather, they are triggered by external energy, which breaks molecular bonds and generates activated molecules. These activated molecules then split into free radicals that have a short lifespan but are highly reactive. The free radicals collide with other molecules, resulting in new products, while simultaneously generating more free radicals that continue to react with other molecules. When the burning combustible gas passes through the narrow channels of the flame arrestor, the probability of collisions between free radicals and the channel walls increases, resulting in a decrease in the number of free radicals participating in the reaction. When the passage of the flame arrester becomes narrow enough, collisions between radicals and the wall of the passage become dominant. As the number of radicals decreases sharply, the reaction cannot proceed any further; in other words, the combustion reaction cannot continue to spread through the flame arrester.

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