Why is an explosion-proof design needed for the valve position transmitter?
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Everyone, why is explosion protection required for mechanical on/off valve position indicators? ? Secondly, is this DI contact a dry contact or a wet contact? Is the DO output to the solenoid valve dry or wet?
Whether it is intrinsically safe or flameproof is determined by the electrical classification of the explosive hazard area; if it is flameproof, then flameproof instruments are naturally used. The 2DI point is a dry node. The 3.DO output to the solenoid valve is a wet node and requires power supply
1. In accordance with explosion-proof requirements, instruments in explosion-proof areas must be explosion-proof; when choosing mechanical valve feedback devices, is the use of explosion-proof types based on considerations related to the circuit? 2. Whether the DI terminals are dry contacts depends on the input signal – they could be wet contacts (you can request that they be dry contacts). 3. The DO output to solenoid valves is a wet contact, and power supply is required
Does a mechanical switch need to be explosion-proof even when it has no energy? Don’t understand
When the mechanical switch is connected to the system card, voltage is applied – so how is it possible that there is no energy? Sparks may still be generated when it is disconnected or closed.
I’ve never seen the signal from a dry contact in any device produce sparks.....
Think about the uses of explosion-proof thermoresistors and thermocouples
Reply to 6# nihaocarter: The sparks I’m referring to are not necessarily those visible to the naked eye; what I mean is that the energy generated in an instant by such actions can potentially cause flammable gases to catch fire and lead to an explosion. Therefore, explosion-proof or intrinsically safe designs are necessary. It’s not necessary unless the area where the switch is located is not a explosion-proof area.
Reply to 8#: What’s a pidcontroller like? Our company uses P+F’s contactless type for this purpose; you can give it a try
Reply to 7# dowan: It seems like their working principles are different, so what do you think? ?