How to select instruments when both gas explosion protection and dust explosion protection are required
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When a gas explosion hazard area and a dust explosion hazard area coexist and overlap, how should the explosion protection rating of the relevant instrumentation be selected? Can a gauge for use underground in mines be selected? Or is it possible to use a higher-grade protective enclosure for the intrinsically safe instruments used in gas explosion-proof areas? Furthermore, since GB50058 does not provide any guidelines for such composite explosion-proof areas, which standard should be referred to?
Just select it according to the gas explosion protection requirements
Can intrinsically safe gas systems also achieve intrinsically safety in areas at risk of dust explosions?
If you don’t understand something, don’t speak recklessly; otherwise it’s easy to lead others to make mistakes! Inertial instruments must also have a dust intrinsically safe certification of type E*aD in order to be used in areas prone to dust explosions, while flameproof instruments need to have a flameproof dust certification of type Ex tD to be used in such areas ； Additionally, attention should be paid to the surface temperature requirements; the explosion-proof certificate specifies the allowable surface temperature, which must not be exceeded, otherwise it is not suitable for use.
GB 3836 Explosive atmospheres GB 12476 Electrical equipment for use in flammable dust environments
According to IEC60079 or GB3836, explosion-proof equipment is divided into 3 categories: Category I is for use in mines, Category II is for gas protection, and Category III is for dust protection； Obviously, the explosion-proof equipment that needs to be chosen is one that meets both Category II and Category III requirements; Category I mining equipment must never be used. Many explosion-proof devices these days meet both gas explosion prevention and dust explosion prevention requirements; you can find out by checking the selection catalogs of various manufacturers ； The specific type of explosion protection to be used depends on whether the hazardous area is classified as Zone 1 or Zone 2, the properties of the gas/dust, and the accumulation of dust, among other factors.
Gases and dust are two different categories; it is impossible to determine which one is higher or lower!
Since explosion-proof instruments can all pass dust explosion protection certification, then dust explosion protection must be a trivial matter, right? ..., the protection rating of the instrument’s casing is estimated to be IP65; preventing dust entry is as simple as dipping it in a duck’s urine, right? ! Don’t make a big deal out of such a trivial matter. Intrinsic safety circuit + IP65 protection level; explosion-proof – no problem at all. . . .
It is recommended to consider the protection level; one should not focus solely on the explosion-proof rating. The selection process itself involves a combination of protection and explosion-proof features, as there is a presence of both gas and powder media. It is advised to opt for a higher level of gas explosion protection. This is just my personal opinion for reference only
Then choose the one with dual markings, that is, one that has both a gas explosion protection marking and a dust explosion protection marking. Definitely do not choose the mining version, as these two types are designed for different application environments