Sensors for dust explosion protection

With the implementation of Atex94/9/EG standards, the scope of dust explosion has also expanded accordingly. For a long time, the regulations for areas 10 and 11 that have been used as hazardous areas for combustible gas explosions have now changed, with the addition of a regional scale and the provision of new names. This also requires that the redistribution of the explosion-proof zone is consistent with the required inspection and control equipment, and that the same method can be used for security protection in the new and old explosion-proof areas.

Although the physical classification and safety protection of flammable gas mixtures and dusts are obviously different, it is very important to use the same standards and methods as the IEC and CENELEC organizations to solve the safety protection of two different types of substances. meaningful. This two-pronged approach has many advantages for explosion-proof equipment and equipment manufacturers. For example: reliable technology, rapid product development time, lower new product development costs and so on. At the same time, the certification method and certification process of new products are also well-known processes. On the other hand, users of these safety protection instruments and equipment can also easily select explosion-proof equipment and equipment in different application areas based on their existing experience. This is exactly the business principle of Pepperl+Fuchs: The spectrum of the explosion-proof sensor is not classified according to the gas sensor and the dust sensor, but is classified according to the application purpose. In this way, when a large number of certification licenses are obtained, the famous products on the market will not cause confusion between gas and powder when they are used. There are two major advantages: on the one hand, the procurement costs can be reduced, and the cost of logistics inventory can be reduced. On the other hand, , has a higher use of security.

Comparing the two explosion-proof safety codes EN50020 (explosion-proof type, internal safety "I" gas explosion-proof) and PrEN61241-11 (explosion-proof type, internal safety "iD" dust explosion-proof), people will see almost no difference between the two. Correspondingly, for example, the cylindrical, square and conical explosion-proof sensors manufactured by Pepperl+Fuchs, which have been certified, have different reaction times and sensors with different interface technologies are suitable for gas explosion-proof and dust explosion-proof applications. After adopting the method of multiple naming of the same product, it can be completely prevented from being mixed with other different products. In this way, not only when the sensor is selected for use, but also in the production process of the integrated circuit board, products that are familiar to them can be used without introducing new technologies.

From the aspect of performance evaluation, the three contents stipulated in the ATEX safety and explosion protection technical specification are not only in terms of users, but also in the classification catalogue of test instruments in production plants, and in the field of dust explosion-proof, all are in accordance with DIN EN 50281-1-2 (Easy Electrical tools for fire, explosive, and dust applications (Section 1-2: Electrical tools protected with enclosures) There are certain differences in the safety protection of flammable gases in the 22nd zone. The main difference is that flammable and explosive dust is no longer judged only by the probability and range of occurrence, but also by electrical performance. When there is an indicator below the prescribed boundary value, the electrical tool can be assigned to the 3D level, otherwise it should be attributed to Zone 22. Taking into account the habits of the home, relatively safe protective measures were chosen for normal working conditions. Such electrical tools should also be attributed to the 2D class. The required certifications and requirements for the names of electrical appliances are all part of the field of combustible gas explosion protection.

Pepperl+Fuchs company belongs to this level of security protection products, classified as 3D grade products, the advantage of this classification is that: Compared with the iD level of self-protection sensors, no special disconnect switch is needed, because in the ordinary Under working conditions, 2-wire, 3-wire, or 4-wire electrical tools can be used. The operating voltage can be up to 60V DC and the output current can reach 200mA. When there is a suitable product name in the product catalog: With the product manual available to the user, the originally used product with a large market share can still be used in principle.