Placing a water leak detector on cotton
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Hi
I need to place a water leak detector on a surface which is very uneven (a badly laid concrete underfloor). In its current condition, water running along the surface does not set off the sensor, however if I place the sensor on a small sheet of cotton wool, when a leak occurs the cotton wool absorbs the water and swells up enough to complete a circuit (therefore triggering the sensor) using the 2 metal probes on the underside of the device.
Obviously cotton is not conductive, and I understand that it has an ignition point of ~200c, however does this seem risky i.e. is there any chance that it could ignite somehow? It runs off a 3v battery, and the model is DY-SQ100B (I'm not posting a link to a retail site, as this may be viewed as spamming).
Thanks!
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@celestial it’s safe. 3.3V won’t ignite anything.
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@mfalkvidd - I thought as much, but the confirmation is reassuring. Thanks!
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@celestial I've done several water detectors using these units:
https://www.amazon.com/dp/B01FDGUHBM/The cotton is a good idea.. but might be a hard time drying out. I might switch to a synthetic... like stuffed animal stuffing that won't rot like cotton. Also.. to increase conductivity you can sprinkle in some table salt that greatly increases the sensor reliability.. especially if you're measuring things like AC condensate (which is non conductive alone).
T.Weeks
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Another thing to try, which I think might be better, would be to use tinned wire, with no insulation on it, and run two closely parallel tracks of it back to your electronic detector to extend the water detection range. When water joins the two wires, it will create a detectable event. It won't rot, and it should be easier to keep clean. It should also detect a leak faster. Not sure what the range limit would be, but probably further than you might guess without actually trying it.
If you decide to try it, please report back as to how it went!
In a sense, it is what my leak detector already does, except wrapped around its perimeter: https://www.openhardware.io/view/534/Extremely-Simple-Arduino-Pro-Mini-LoRa-Water-Leak-Detector
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Funnily enough I saw an ad for water detecting bed protectors for incontinent people at the hospital just yesterday. They seem to run a material like aluminium foil under the sheet in a pattern. Maybe worth looing into as these seem to fit the bill for what you need.
The ones I saw fit to a system to alert a call centre via the phone if the person wets the bed. I didn't see the price though as no need for one (not yet anyway!).
