Working principle of flame arrester

There are mainly two views on the working principle of flame arresters: one is based on heat transfer; One is based on the wall effect.

Heat transfer effect

One of the necessary conditions for combustion is to reach a certain temperature, that is, ignition point. Below the ignition point, the combustion will stop. According to this principle, the spread of flame can be prevented as long as the temperature of the burning substance is reduced below its ignition point. When the flame passes through many small channels of the fire arresting element, it will become several small flames. When designing the fire arresting element inside the flame arrester, expand the contact area between the small flame and the channel wall as much as possible, strengthen heat transfer, and reduce the flame temperature below the ignition point, so as to prevent the flame from spreading.

Wall effect

Combustion and explosion are not direct reactions between molecules, but are excited by external energy. Molecular bonds are destroyed to produce activated molecules. The activated molecules split in o short-lived but very active free radicals. The free radicals collide with other molecules to produce new products. At the same time, they also produce new free radicals and continue to react with other molecules. When the combustible gas passes through the narrow channel of the fire retardant element, the collision probability between free radicals and the channel wall increases, and the free radicals participating in the reaction decrease. When the channel of the flame arrester is narrow to a certain extent, the collision between free radicals and the channel wall is dominant. Due to the sharp reduction of the number of free radicals, the reaction cannot continue, that is, the combustion reaction cannot continue to spread through the flame arrester.

With the reduction of the size of the flame arrester channel, the collision probability between free radicals and reactive molecules decreases, while the collision probability between free radicals and the channel wall increases, which promotes the reduction of free radical reaction. When the channel size is reduced to a certain value, this wall effect causes the condition that the flame cannot continue to propagate, and the flame is stopped. Therefore, the wall effect is the main mechanism to prevent flame