Shenhai odolný proti výbuchu
V oblasti inžinierskych konštrukčných materiálov, najmä s technickými plastmi, it’s crucial to assess not just their mechanical and electrical characteristics, ale aj ich tepelná stabilita a schopnosť odolávať statickej elektrine.
Thermal Stability
For explosion-proof electrical equipment, the plastic materials used in casings are required to demonstrate superior thermal stability. In specified testing conditions, the maximum temperature decrease should be 20K compared to the Temperature Index (TI) at 20000 hours on the heat resistance curve.
Anti-static Capabilities
Plastic materials must possess effective anti-static properties, which include measures to avert the generation and accumulation of static electricity. This can be achieved by adding appropriate conductive additives to lower the material’s volume and surface resistivity. When tested under specified conditions (10mm electrode distance), if the surface insulation resistance of modified plastic components does not exceed 10Ω, the material is deemed effective in preventing static build-up.
Beyond modifying the plastic material, static fire hazards can also be mitigated by limiting the exposed surface area of plastic casings (or parts) v elektrických zariadeniach odolných voči výbuchu. Table 1 details the limits on the maximum surface area of plastic casings (or parts), while Table 2 specifies the diameter or width of elongated plastic parts, and the thickness of plastic coatings on metal surfaces.
Maximum Surface Area for Plastic Casings (or Parts)
| Equipment category and level | Equipment category and level | Maximum area S/m ² | Maximum area S/m ² | Maximum area S/m ² |
|---|---|---|---|---|
| ja | ja | 10000 | 10000 | 10000 |
| II | Hazardous areas | Zóna 0 | Zóna 1 | Zóna 2 |
| II | IIA level | 5000 | 10000 | 10000 |
| II | IIB level | 2500 | 10000 | 10000 |
| II | IIC level | 400 | 2000 | 2000 |
Maximum Restricted Dimensions for Special Plastic Parts
| Equipment category and level | Equipment category and level | The diameter or width of a long strip/mm | The diameter or width of a long strip/mm | The diameter or width of a long strip/mm | Metal surface plastic coating thickness/mm | Metal surface plastic coating thickness/mm | Metal surface plastic coating thickness/mm |
|---|---|---|---|---|---|---|---|
| ja | ja | 20 | 20 | 20 | 2 | 2 | 2 |
| II | Hazardous areas | Zóna 0 | Zóna 1 | Zóna 2 | Zóna 0 | Zóna 1 | Zóna 2 |
| II | IIA level | 3 | 30 | 30 | 2 | 2 | 2 |
| II | IIB level | 3 | 30 | 30 | 2 | 2 | 2 |
| II | IIC level | 1 | 20 | 20 | 0.2 | 0.2 | 0.2 |
Ďalej, plastics used for making casings (or components) of explosion-proof electrical devices should also exhibit excellent plameň resistance and pass various tests like heat and cold resistance, and photoaging.