Pulasitiki Yopangira Zida Zamagetsi Zophulika

Mu gawo la zomangamanga zomangamanga zida, makamaka ndi mapulasitiki a engineering, it’s crucial to assess not just their mechanical and electrical characteristics, komanso kukhazikika kwawo kwamafuta komanso kuthekera kokana magetsi osasunthika.

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) pazida zamagetsi zomwe sizingaphulike. 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
Ine	Ine	10000	10000	10000
II	Hazardous areas	Zone 0	Zone 1	Zone 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
Ine	Ine	20	20	20	2	2	2
II	Hazardous areas	Zone 0	Zone 1	Zone 2	Zone 0	Zone 1	Zone 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

Komanso, plastics used for making casings (or components) of explosion-proof electrical devices should also exhibit excellent lawi resistance and pass various tests like heat and cold resistance, and photoaging.