DFRobot KIT0139 Industrial Stainless Steel Submersible Pressure Level Sensor

An industrial depth sensor, not a hobby float switch. Drop the 316L stainless probe into a tank, a well or a cistern and it reports how deep the liquid is, up to 5 metres, to within half a percent. It speaks 4-20 mA - the format industry uses because the reading survives a long cable run that would ruin a voltage signal - so it needs a 12-36 V supply, not the 5 V from your board. The kit includes DFRobot's converter, which turns that loop current into a 0-3 V signal any analogue pin can read.

Key features

• Measures 0-5 m of liquid depth to +/-0.5%, with 5 m of cable
• 316L stainless probe, IP68 - built to stay submerged permanently
• 4-20 mA current loop: unaffected by voltage drop down a long cable
• Needs a separate 12-36 V supply; your board only reads the signal
• Includes the Gravity converter board (0-25 mA in, 0-3 V out)
• Under 4 mA or over 20 mA reads as a fault, so a broken cable is detectable rather than silently wrong
• Thin red is V+, black is V-, and the THICK red tube is an air vent - keep it dry and unblocked or the readings drift with the weather