I mean, it should be close to pure water, right? Why would some condensation short electronics?

  • @litchralee@sh.itjust.works
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    2 days ago

    If water vapor was the only thing airborne, then this would be mostly plausible. But the reality in any typical environment is for small particles of dust, soot, microplastics, VOCs, etc to be in the air, in addition to the usual suspects of oxygen, nitrogen, carbon dioxide, etc. Some of those will increase the conductance of water, when condensed upon a cool surface. Think of water vapor as a lint filter that floats around the room until it lands on something.

    But even in a hermetically sealed environment with only the typical atmospheric mix of oxygen and nitrogen and other trace elemental gases, and then water vapor, there’s still a problem. Air has a conductivity – measured in Siemens, the inverted unit of Ohms which is resistance – of 3-8 x 10^-15, meaning it will not conduct much at all. But compared to condensation upon a PCB in this sealed environment, DI water has a conductance of 5.5 x 10^-6. That is 1,000,000,000x times more conductive, although it’s still a tiny amount.

    The reality is that all circuits and electronics leak small currents here and there, even through the air or through their PCB substrates. But the sum total of these leakage and creepage currents will be negligible in all but high-voltage circuits. Though that’s only under the rated environmental conditions.

    When air is fully saturated at 100% humidity, some of those currents become noticeable. And for high-voltage switchgear, it can become an issue very quickly. But outright water on most circuits would be disastrous due to arcing or shorting or both, even for low voltage things.

      • @litchralee@sh.itjust.works
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        1 day ago

        Wireless water, coming right up: https://www.youtube.com/watch?v=j_QfX0SYCE8

        In all seriousness, not all particulate sticks to water vapor consistently, sometimes if said particulate is non-polar – the lipid envelope of one SARS-CoV2 comes to mind. It would be more effective to clean the air using a furnace filter taped to a box fan, and it’s only up from there: electrostatic filters or actual air cleaners with a filter.

        That said, some console humidifiers push air through essentially a large sponge, and that can already be effective at trapping larger particulate, although not effective for tiny virus-sized particles.