The high surface temperature of any part of the equipment exposed to a potentially explosive environment or capable of forming a dust layer should be lower than the ignition temperature of the explosive gas mixture.
At high ambient temperatures, the local high surface temperature of plastic materials for non-metallic components should be 20K lower than the temperature index TI corresponding to the 20 000h point.
The surface resistance measured at a temperature of (23 ± 2) ℃ and a relative humidity of (50 ± 5)% shall not exceed 1G Ω.
For materials used to manufacture Class I equipment casing components, for Ma and Mb grades, the total content of aluminum, titanium, magnesium, and zirconium is not allowed to exceed 15% by mass percentage, and the total content of titanium, magnesium, and zirconium is not allowed to exceed 7.5%.
The materials used for manufacturing the shell components of Class II or III equipment shall not exceed 10% by mass for Class Ga and Da: the total content of aluminum, titanium, magnesium, and zirconium shall not exceed 7.5%;
For Gb and Db grades: the magnesium content is not allowed to exceed 7.5%;
For Gc and Dc levels: no special requirements.
Non electrical equipment such as pneumatic hoists have the characteristics of no electric sparks, high frequency, and continuously variable speed, and are highly favored by industries such as petroleum, chemical, and mining.
With the widespread application of non electrical equipment in flammable,
explosive, and high dust workplaces, in explosive hazardous environments, in addition to hazardous ignition sources such as sparks and high temperatures generated by electrical equipment,
hot surfaces, open flames, hot gases/liquids, mechanical sparks, adiabatic compression, vibration waves, chemical reaction heat release, aluminothermal reactions, and dust spontaneous combustion generated by non electrical equipment Arc and electrostatic discharge are equally important ignition sources that cannot be ignored.
Therefore, the design, manufacturing, installation, and use of non electrical equipment or mechanical components of electrical equipment used in explosive hazardous environments should be given equal attention to electrical equipment in order to ensure the safe operation of industrial sites.