Explosion protection requirements for Zone 1
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Summary of the situation: The environmental requirements dictate an explosion-proof classification of Zone 1. When the plant was built, the power supply lines for the motors of all pumps, as well as those for the control panels on site and various instrument terminals, were connected using plastic-coated metal hoses along with explosion-proof connectors before being fed into the wiring boxes. Problem-solving: Does this type of connection meet the explosion-proof requirements for Zone 1? Is it necessary to replace it with an explosion-proof hose and explosion-proof connector before connecting it to the junction box? Are there any requirements? Since the workload is very large in this case, I’m seeking solutions. Thank you!
Explosion-proof flexible connection pipes are suitable for use in areas classified as Zones 20, 21, and 22 with flammable dusts, as well as in areas with explosive mixtures of categories II B II C and groups T1–T6. They are used for connecting the incoming and outgoing wires of explosion-proof electrical equipment, or in situations where it is difficult to bend steel pipes for wiring purposes. ①At the power inlet of electrical equipment, when it is difficult to connect using steel pipes, explosion-proof flexible connectors can be installed. ②For electrical equipment with vibration, such as explosion-proof motors, although it is easy to connect them using steel pipes, the joints in steel pipe wiring tend to loosen due to the vibrations generated during operation; therefore, flexible connection tubes must be installed at the power inlet of explosion-proof motors. Since replacing the lamp tube or starter in explosion-proof fluorescent lamps requires removing one end of the lamp to do so, when using steel pipes for wiring, an explosion-proof flexible connection tube must also be installed at the power inlet. Explosion-proof flexible connection pipes need to be installed when the steel pipe line has complex bends, or when the steel pipe passes through expansion joints or settlement joints in buildings. Before installing the explosion-proof flexible connection tube, a visual inspection should be carried out to ensure there are no cracks, holes, mechanical damage, or deformation; moreover, the installation location should have a temperature not exceeding 40°C. When in use, its bending radius should not be less than 5 times its outer diameter, and the number of meshing turns of its flame-retardant thread must be at least 6.