Seeking help with wiring issues for flameproof pneumatic valves. . .
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There is a project that requires the installation of a batch of pneumatic valves, of the explosion-proof type. However, these valves do not have rubber seals at their wiring ports. Although explosion-proof flexible hoses are used, the absence of rubber seals at the wiring ports means that the internal wiring terminals of the valves are in contact with the external environment – so how can these valves be made explosion-proof? How do flameproof pneumatic valves achieve flame protection? What are the requirements for wiring? Do I need to do sealing for direct wiring? How to do it?
Pneumatic instruments do not have explosion-proof issues. The \"explosion-proof pneumatic valve\" you mentioned likely refers to a valve positioner; since its electrical interface lacks sealing rings, a sealing connector should be installed.
We encountered this issue on site as well; it involved transmitters and cables that were shielded. The EMC flange connectors with protective hoses could not provide explosion protection, while the EMC flange cables without protective hoses achieved a perfect seal. However, some of the project owners failed to understand which elements were more important and insisted that hoses should also be used, resulting in a deadlock. . . . .
Pneumatic valves should not have power cables; I assume you are referring to the signal wires of such valves. Theoretically, it is easier to make signal wires intrinsically safe, and lower sealing requirements are needed for them – no sealing is even necessary in some cases. But since you have chosen an explosion-proof pneumatic valve, the cable entry points must have appropriate sealing measures. Domestic products usually come equipped with cable clamps with sealing joints, while imported products require the user to select the appropriate type of cable clamp with sealing joint based on whether the installation site falls under Zone 1 or Zone 2. For Zone 1 applications, explosion-proof cable clamps with packing seals are required, whereas for Zone 2 applications, those with ordinary rubber seals are sufficient.