Liquid depth or height sensor

Hardware
1

Is there either a

  1. liquid (water) depth sensor
  2. distance sensor I could statically affix to a location to get rising water levels
that communicates via I2C? My ground is wet at specific times of the year and my sump goes off every 4-5 minutes. Other times of the year it'll go off once a month. I'd like to measure the depth of the water from the bottom (there's always some standing water) or the height to the lid with a distance sensor where I would calculate

depth = Hoverall - Hwater_surface.

The sump depth is maybe 20"/50cm.

I would post the results to a MySQL DB to generate nice graphs, but I’d also like to save the results to an SD card, if possible, for backup purposes.

2

I’ve used the JSN-SR04T waterproof ultrasonic range detector. It has a resolution of about 0.5 cm, but it’s really cheap on eBay or Aliexpress (under US$8.00). It outputs a pulse you measure the length of. The most annoying thing in my opinion is the minimum distance of 24 cm. Thus is must be mounted fairly high above the water surface. The maximum ranges is 4.5 m, so that’s usually fine.

3 Likes
3

I’d use Vl53l0x sensor for that. Breakout boards are available for few bucks on eBay and there are already available drivers for Particle devices. I myself using two of them on i2c bus for obstacle detection on a robot. They are accurate to the mm and measure distance from ~2 meters down to few mm with default settings.

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4

The problem with the ToF sensors like the VL53L0X to detect liquids (esp. water) is the low reflectance of the surface.

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5

@rgould,
I use maxbotix sensors for water level measurement. The ones I’m using are expensive($100-ish), but made for exposed locations, and have filters especially for sensing tank levels. I know that they have i2c, but I don’t use that. I’ve found them very reliable, pretty simple, and robust.
J

3 Likes
6

Also the VL53L0X is a pain to calibrate. I think there is a newer model coming out this year that should be a lot better.

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8

I have some custom made pressure sensors. It sits on the bottom and translates the head pressure of the water into the height of the water column above it. They are accurate within a quarter inch of water and have a stainless diaphragm so they won’t corrode sitting in the water. i2c interface.

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9

Have you run into this thread?
Measure Oil Level (or any liquid) and alert - hardware + firmware/code

2 Likes
10

Ran into this, have not read it though.

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12

Get a sealed pressure sensor. The MS5803-xx sensors are great for this kind of thing. You can stick the sensor somewhere dry and protected, and then connect it via a hose to the bottom of the sump. Just make sure the sensor is at the same height as the bottom of your sump.