One mistake: explosion-proof electrical equipment can be waterproof

Many people believe that the reason why explosion-proof electrical equipment can be explosion-proof is that its shell can prevent the dangerous gas from entering its interior, its sealing performance must be very good, can prevent rain from entering, and it should be installed in the outdoor use. In fact, this is to confuse the explosion-proof form of explosion-proof electrical equipment and the two concepts of shell protection level.

Explosion-proof electrical equipment is divided into different explosion-proof forms according to its different explosion-proof principles. Explosion-proof electrical equipment is an electrical equipment with an enclosure that can withstand the explosive pressure of the explosive gas mixture inside and prevent the explosion inside the enclosure from propagating to the explosive mixture around the enclosure. Obviously, its explosion-proof performance has nothing to do with the protection level of the shell, the standard has no special requirements for the protection level of the shell, as long as it meets the requirements of the protection level of the motor and low-voltage electrical appliance, but the material and mechanical strength of the shell are strictly stipulated. Increased safety type explosion-proof electrical equipment is electrical equipment that does not produce arc, spark or high temperature equipment structure that may ignite explosive mixtures under normal operating conditions, and takes measures to improve the degree of safety to avoid these phenomena under normal and approved overload conditions. The intrinsically safe explosion-proof electrical equipment (mostly seen in small weak current equipment) is an electrical equipment whose electrical sparks and thermal effects generated by all circuits under the specified fault state cannot ignite the specified explosive mixture. These two types of explosion-proof electrical equipment either do not produce sparks and high temperatures, or produce sparks and thermal effects are not enough to ignite explosive mixtures, obviously its explosion-proof performance is also unrelated to the shell protection level, so the standard has no special requirements for its shell protection level.

It can be seen that the vast majority of explosion-proof electrical equipment can not prevent gas or water from entering its interior, so these explosion-proof electrical equipment can not be directly installed in the outdoor open place, and can not wash its shell with water. In fact, the waterproof performance of the equipment is completely determined by its shell protection level, usually used for outdoor rain-proof electrical equipment shell protection level should reach IPX5 (that is, can withstand water from all directions without water), so in the purchase of explosion-proof electrical equipment must also put forward the shell protection level requirements. Another point to note is that the explosion-proof electrical equipment used outdoors should be corrosion-resistant.

Misunderstanding two: Gas explosion-proof electrical equipment can be used in dust explosion dangerous places

At present, many people still lack a full understanding of dust explosion-proof and dust explosion-proof electrical equipment. In practical applications, whether it is a dangerous place of gas explosion or a dangerous place of dust explosion, gas explosion-proof electrical equipment is selected. In fact, this is wrong, because from the explosion-proof principle of the explosion-proof electrical equipment, the vast majority of gas explosion-proof electrical equipment shell protection level is lower than dust explosion-proof electrical equipment, if the gas explosion-proof electrical equipment is used in dust explosion dangerous places, the dust will enter the equipment and accumulate, which will prevent the safe operation of explosion-proof electrical equipment. Of course, the shell protection level of gas explosion-proof electrical equipment can also be improved for dust explosion danger places, but this is extremely uneconomical, because the flameproof, increased safety and other functions used for gas explosion-proof are wasted.

Conversely, can dust explosion-proof electrical equipment be used in gas explosion hazardous places? The answer is no. Because the dust explosion-proof electrical equipment is only a higher protection level of the shell, it can not prevent explosive gases from entering the shell, and there is no explosion-proof measures such as flameproof and increased safety, so these two explosion-proof electrical equipment must not be changed.

Misunderstanding 3: Electrical equipment in agricultural products crushing sites does not need to be explosion-proof

This is a common misunderstanding in the vast rural areas. In fact, explosive dust can be divided into the following four types: explosive dust, flammable conductive dust, flammable non-conductive dust and combustible fiber. Agricultural dust belongs to combustible non-conductive dust. Taking highland barley powder as an example, its various explosion risk indexes are comparable to those of red phosphorus powder in metal. Therefore, the explosion-proof problem of agricultural products crushing processing sites must be paid enough attention to, and explosion-proof electrical equipment must be selected.