Waterproofing the water sensor!

Projects General Guidance
1

Yes, my project has come to this. I need to waterproof a water sensor.

I have the following sensor. Do you think I can cover / spray / tape the bottom section in the photo including the jumper connections and the small LED so that the top section where the parallel wires are just exposed to water, and then submerse this sensor into a deep bucket?

I'm hoping I can use silicone , hot glue, epoxy or conformal coating but how reliable would this be?

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ALSO to protect from corroding in time, how sensible would it be if I limited the amount of time sensor is on? Would it make sense if I turn on the sensor for 5 seconds every 10 minutes? more info on this here: http://www.homautomation.org/2014/06/20/measure-soil-moisture-with-arduino-gardening/

2

Link?

It looks like a resistive "rain sensor".
It relies on the conductivity of water, so if you coat it it won't work anymore.

Only capacitive moisture sensors can be coated.
Leo..

3

sorry I meant to coat only the bottom section in the photo where the pin connections and led is.

4

remove the LED,

  • get liquid tape.

or

  • use hot glue

or

  • cut the board, connect wires, keep the electronical bits out of water.
5

nervusvagus:
http://www.homautomation.org/2014/06/20/measure-soil-moisture-with-arduino-gardening/

this is not a soil moisture device.
you can use pretty much any metals to test for moisture, you do not need to buy a board
and you can put the electronics in an enclosure.
it would be better to provide the details of what you want and we can offer solutions, not band-aid fixes.

6

He said he wants to put it in a bucket. I'm guessing this is to sense the presence or absence of water in a deep bucket.

Well, the thing is, you don't see sensors like this in commercial products. They aren't reliable because they are always subject to corrosion. It might only work for a day or a week. If that's all you need, then glob lots of silicone sealant onto it and have fun with your experiment.

For long term use, you need a way to get the sensor out of the water. The best level sensor is an ultrasonic distance sensor looking down on the water surface. This will have difficulty differentiating between almost-empty and empty. A capacitive sensor is completely insulated from the water and may work. A float type sensor is probably best. There are a lot of float switches available as commercial products.

7

I read somewhere that float Arduino type switches from china arent much reliable because of their mechanical nature. However these rainsensors are awful. You are right.
I used Epoxy to cover the wires and the led on the sensor however the sensor part started corroding after only a day immersed in water.

8

Fancy board with relay to operate e.g. a pump.
But water detection seems the same. Bare wires in water.

Tell us more about your project.
Maybe there is another way.
Leo..

9

I deleted the link I sent, yes that was just a fancy board with relay.

My project is a small propagation Greenhouse made of an IKEA box.

The water sensors are in 2 or 3 locations.

  1. Main Water Bucket

  2. Humidity Steam Cup - It produces humidity, its a car humidifier made of a small cup.
    As seen here:
    http://i00.i.aliimg.com/wsphoto/v0/32244199124/Car-mini-font-b-usb-b-font-humidifier-font-b-cup-b-font-computer-humidifier-air.jpg

  3. havent decided on this one yet but if it works, a Water Heater. To provide heat.

If the water runs out in humidifier (or the water heater) I provide water using a pump and the Main Water Bucket.

10

Sounds good. Float switches will work just fine for that.

11

So the original question was waterproofing the component section of the board.

Try thinning clear silicone with acetone or paint thinner and paint it on with a disposable brush. It'll act like a flexible conformal coat that can be scraped off if needed.

12

If you are serious about using this method i would suggest dip coating, 2 dips with polyurethane or proprietry liquid.

If you use acetone solvents the previous coat can be dissolved away.

Personally i would use a low viscosity 2 part epoxy/strike that , its poly something specifically for the purpose.
Thats purely because i have some.

Transformer varnish may work but that is soluble in acetone.

13

There are many products on the market for waterproofing electronics. Conformal coating is usually the best. I have used a clear rubberized spray, liquid tape, and liquid tape in a spray can and I also have several types of conformal coating in spray cans. All of them make it a pain when it comes to service. Some more than others.

Any time you have probes in water there will be electrolysis taking place and small amounts of the metal will be removed. Some metals will be less prone to electrolysis.