FS20 Liquid Level Sensor

FS20 Liquid Level Sensor

In home automation environments there is also the need to measure the liquid level left in a barrel (i.e. rain barrels) and have a notification when the barrel level reaches a critical level.

A research in the internet showed that the following technologies exist for liquid level (maily water level) measurement:

• resistive measurement by having a series of wires at diferent level placed and if the resistance is nearly 0 Ohm for a given electrode, so this level is flooded.

For this kind of measurement, a series of electrodes are necessary and the level may only be estimated for a range (10%, 20%, 30%, ...)

• capacitative measurement by having two wires in a specific distance to each other will be put into the liquid and the change of the capacity between this wires will indicate the liquid level.
• ultra sonic liquid surface measurement will measure the time between sending of specific ultra sonic waves and it's reflection. There is a promising out of the box sensor SRF02 from Devantech providing all functionality by an I2C / RS232 interface. Also the SRF05 is promising and maybe better suitable. useful information about USB and I2C

In additional a floating switcher (Schwimmerschalter) will ensure that a water level below a minimal level will be monitored safely. This is important to use the lowest level switch as a pump turn off switch for avoiding damages to the pump.

Controller / radio module

The controller will be the CPM module from busware. It communicates with the ultra sonic sensor using I2C and will report the sensor values very similar to GardenaBodenfeuchteSensorFS20Modul.

Schaltplan