Water Level Monitor Sensor - Hydrostatic Pressure

Hi Everyone! Thanks for stopping by!

I'm relatively new to the electrical engineering and instruments and controls world, though I have 5 years experience as a mechanical engineer, so a little extra explanation is appreciated!

The question: I am trying to build a proof-of-concept circuit using an Arduino UNO that measures water level in an open container. What sensor would be best for this circuit? Ideally, the sensor should be able to be in direct contact with the working fluid (tap water) on one side - my intent is to measure the hydrostatic pressure of the water via a port and tube at the bottom of the container. The tube will be filled with water and attached directly to the sensor port. The operating pressure range is 0-1 psig. I am familiar with analog and I2C protocol but I can learn a different communication protocol if necessary.

I have spent hours filtering pressure sensors on Digi-Key and have tried a few options, most recently the NXP MPVZ4006GW7U. This sensor is nearly perfect, except the datasheet says "for dry gas" despite the datasheet also saying possible applications include water level detection, so I'm hesitant to hook up a hose full of water to it. I figure I'd reach out to the community to see if anyone else has experience with this topic.

Side note: if someone knows of a breakout board or similar assembly that already does this, please let me know. I don't need to reinvent the wheel.

If I can provide any additional information please let me know!

Thanks for your time! I appreciate any and all input!

Search for “bubbler level sensor”.
For a hobby project you would use an aquarium air pump and a one way valve. Switch on the pump, monitor the pressure until it stops rising, switch off the pump, wait a couple of seconds then take a reading.

If you want simple, quick and economical I would be looking at, as suggested, a bubbler system.

Ron

Most low pressure sensors have the sensor element open to the measuring fluid rather than a stainless steel wetted diaphragm - which is what you need .
( the diaphragm adds some stiction to the reading unless a large area ( ie expensive) transducer is used) .

The bubbler uses dry air so overcomes that issue and worth a punt , I would come up with a system that didn’t leave the sensor ( when not bubbling ) exposed to damp air , which will still shorten its life . The NRV sounds a good idea as mentioned or a solenoid valve

As an aside some early car fuel gauges used this principal where you had a little hand pump and pumped away every so often.

Search for “DS1603L Ultrasonic Liquid Level Sensor”
Installed on the outside bottom of the container, shooting through and up to measure the liquid surface level.
Resolution is 1 mm, but has a blind spot at the transducer of 50 mm.
I paid Cdn $25 on Amazon Jan 28, delayed from China until March 29 (still holding breath).

Using a ESP8266 based D1 Mini Pro, with RS232 to 3v3 signal conditioning on Rx input only; initially it will alert me when my boat fuel tank is full during refueling.
Once calibrated, it will correlate with my YS-401 Fluid Flow sensor which measures the engines fuel consumption (fwiw).

Adafruit sells a few interesting sensors which are immersed in the liquid and produce a resistive output proportional to the liquid level. These would not require any porting of the tank and they would be child's play to interface. But you would be limited to a depth of 12" or less.

These are apparently also available at Digi-Key.

S.

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