BME280 Outside

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Harry48
 
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BME280 Outside

Post by Harry48 »

I bought 2 bme280. One is installed inside my motorhome. The other will be installed outside the van in a box with small ventilation holes. Now I read that these sensors are quite sensible for moisture. Is it wise to embed the sensor in teflon tape? See http://makezine.com/projects/bees-senso ... ve-health/
Are there any other recommandations (I read the datasheet but it was not really helpfull). Thanks

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adafruit_support_rick
 
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Re: BME280 Outside

Post by adafruit_support_rick »

I would think that teflon tape could just as easily trap moisture inside. I don't know how it would affect the barometric pressure reading.
Do you actually need the humidity reading?

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Harry48
 
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Re: BME280 Outside

Post by Harry48 »

Yes I do.
The good thing of teflon tape is that it is semi-permeable. It passes air and water vapor but it stops plain water from entering the sensor-enclosure. The readings of the sensor should therefore be OK. At first sight thats looks good. However, there is one problem. If there is water vapor inside the sensor-enclosure AND the humidity is high AND the temperature quickly drops down then the vapor will condens. And there is no way out because the tape will not allow the condensed water to pass through.
The only thing I can come up with is to build some heating inside the box using a resistor. So if the humidity inside the sensor-box is high (say 90%) the Arduino sends a little current through the resistor generating enough heat to prevent condensation. The temperature reading will be wrong of course. But is seems a small price to pay for these rare occasions that it is needed to protect the sensor from condensed water.
For the moment this is my solution. But maybe there are better ones.

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kennethm4
 
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Re: BME280 Outside

Post by kennethm4 »

3M used to sell a silicone laced tape I used a lot years ago to seal microwave connections outside. Kept the water out and the connectors looking brand new, could get easy access also. If you could find this tape you could water proof your enclosure with it along the seams etc. It does compress and can be reapplied if necessary.

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