Why industrial hazardous area requires explosion proof sensors?

The formation of the explosion needs to meet three conditions, 
It’s oxygen, explosive gas, and detonation source.

In a flammable and explosive industrial environment, the installed transmitter may cause serious damage due to electrical sparks or hot surfaces, resulting in fire or explosion. Such as high-pressure flammable gas storage environment, flammable liquid vapor environment, flammable gas and other substances retention environment, etc., the transmitter used in these places should have an explosion-proof structure.

In the area where hazardous areas of explosion-proof Transmitter are installed, engineers must consider the following items:
1. Leakage concentration 2, ventilation state 3, lower explosion limit 4, flash point 5, release rate of explosive gas (release amount per unit time) 6, release rate 7, boiling point of flammable liquid 8, relative density 9, obstacle

The so-called explosion-proof structure means that the electric spark or the high-surface temperature  of the machine can be prevented from being an ignition source and protected by the casing, and the explosion is limited to the inside of the casing to achieve the purpose of explosion-proof.