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WATER TANK LEVEL MONITOR<br />
Projects<br />
MONITORING WATER<br />
>STEP-01<br />
Under pressure<br />
The pressure sensor at the bottom of<br />
the tank is constantly under pressure,<br />
although this varies as the water level<br />
goes up and down.<br />
>STEP-02<br />
Light reading<br />
The Pi Zero reads the voltage levels on the<br />
two outputs with the help of an analogueto-digital<br />
converter. The GPIO cannot<br />
measure it natively.<br />
>STEP-03<br />
Simple geometry<br />
The Pi Zero uses fluid dynamics and the<br />
measurements of the tank to determine the<br />
volume of the water in the tank. This can be<br />
charted to keep track of consumption.<br />
As we live in 2016, computeraided<br />
monitoring was on the<br />
table. Brian’s method was rather<br />
ingenious: instead of measuring<br />
the water level at certain points, he<br />
measured the pressure of the water<br />
at the bottom of the tank. With a<br />
few extra calculations to take into<br />
more comfortable creating the<br />
project, basing it on a similar<br />
solution employing an Arduino<br />
that he’d seen a few years ago. This<br />
way he managed to save money on<br />
proprietary solutions as well.<br />
“It was tricky to build, but not<br />
because of the complexity of the<br />
I wanted to devise a means to<br />
monitor tank levels to know<br />
when things were running low<br />
account atmospheric pressure and<br />
the size of the tank, the volume of<br />
water could be calculated.<br />
“I used a Pi Zero as the<br />
platform to read the pressure<br />
sensor (via an analogue-todigital<br />
converter), calculate the<br />
tank volume, and post the data to<br />
InitialState for dashboarding and<br />
alerting,” Brian tells us.<br />
His experience with Linux<br />
throughout his career made him<br />
solution,” Brian notes. “The box<br />
I chose is rather small, so it took<br />
some time to squeeze it all in<br />
there. The biggest challenge is the<br />
tight space on the ProtoZero board.<br />
I’m not the best at soldering, so<br />
it’s been slow going at times.”<br />
Brian reports that the solution<br />
works well, with only a minor<br />
repair required after he damaged a<br />
connection. In the future he plans<br />
to upgrade these connectors to<br />
Above The whole thing is connected to the<br />
bottom of the tank in a small grey box<br />
make them a little more rugged,<br />
but otherwise it looks like his<br />
project has helped out enormously<br />
with his water supply.<br />
raspberrypi.org/magpi January 2017 39
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