Can a breather valve be installed on an explosion-proof junction box?
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There is now an explosion-proof junction box with several buttons; both the box and the buttons meet the EExe IIC T6 standard. But the customer wants a vent valve or something similar to remove the condensed water! Here comes the problem: the breathing valve can draw in flammable gases. Is this feasible for boxes with enhanced safety features? What about other types of boxes, such as those with intrinsically safe or flameproof designs? I asked the manufacturer again, and they said that it’s rare to install this on intrinsically safe enclosures, but it has been done before. It is widely used in ordinary junction boxes. The manufacturer also admits that a small amount of flammable gas is drawn in during the suction process, but since the instruments and terminals inside the box are explosion-proof, there will be no problems. What do you all think?
A breather valve should not be installed on an explosion-proof junction box.
Breather valves are generally not installed. If it is necessary to further enhance explosion-proof performance, purified air can be supplied to ensure positive pressure ventilation and prevent combustible gases from entering the junction box.
I also think it shouldn’t be added, but the client (a well-known foreign company) insisted on it, saying that all their boxes are like this.
I have also seen this kind of design, but it was a CO2 compressor disk, with positive pressure inside the disk. According to what your colleague above said, that’s correct
I want to upload the valve manual in PDF format, but I can’t do it. Sigh
If it is positive pressure ventilation, then this question doesn’t arise; the issue is whether it is feasible to install this valve on the intrinsically safe box.
Generally, a breathing valve is not installed; instead, purified air can be supplied to ensure positive pressure ventilation and prevent flammable gases from entering the junction box.
In what climate conditions is the junction box used? How is condensation formed inside the box? If water condensation occurs inside the box, it indicates that the protection rating of the junction box is low, or that the air is humid; when humid air enters the box, water condensation may form as the ambient temperature drops. In such a case, the function of a breather valve is limited; when the breather valve opens, both combustible gases and humid air can enter the tank, causing the aforementioned process to repeat itself. The same problem exists with positive pressure ventilation as well. The best approach is to choose a junction box with a higher protection rating. The corrosion protection rating of the junction box can reach up to IP66. I’m not sure if my understanding is correct.
It’s an IP66 box, but temperature changes will definitely cause condensation water to form. I think it would be good to add a heater.
What was said upstairs makes sense – no protection level can overcome the need for respiration. But the original poster mentioned that the instruments are explosion-proof; then why put explosion-proof instruments in an explosion-proof box? Spent it all on fun?
Well, that makes sense too – the box is designed for enhanced safety, and foreigners require that all instruments be explosion-proof; perhaps this is also one of the reasons why a breathing valve can be installed.
Then just install it for him; after all, he has money. Have him sign it, and install it!
A dehumidifier or moisture-proof bag should be added. Can an electric heater be used? It generates electromagnetic interference (22VAC power supply), which leads to neglecting one aspect while focusing on another. :P
There is absolutely no need to install a \"breather valve\". If foreigners say that’s what they all do, you can confidently tell them that Chinese companies never do such things. Be confident and let foreigners know that the problems they are worried about will not occur with your products – bring honor to the Chinese! If the customer insists on adding it, sure, you can tell them that this product is custom-made, which is why its price is high. It’s like Zhou Yu beating Huang Gai – one is willing to do it and the other is willing to endure it; so why not go ahead?
First of all, for any type of explosion-proof junction box, it is not allowed to modify its enclosure on one’s own, whether it is flameproof or increased safety designed (there is no such thing as an intrinsically safe junction box; intrinsically safety applies to the entire circuit, and if the circuit is intrinsically safe, only the protection level of the junction box is required). Because explosion-proof certification does not guarantee that the modified version still meets the certification requirements. Furthermore, as an explosion-proof ventilation method, simply introducing instrument air is not sufficient; it is necessary to maintain a certain differential pressure, and power must be cut off once this differential pressure falls below a specified value. For detailed regulations, refer to the relevant sections of GB3836. If all the components inside the junction box are explosion-proof, then although the junction box is of an explosion-proof type, it is not necessary for explosion protection purposes, and this can be changed. But after the modification, it can no longer be used as an explosion-proof box. Also, the internal components are explosion-proof, such as buttons and switches. But I’ve never heard of explosion-proof terminal blocks!
It’s not possible; explosion protection requires isolation from the surrounding air