Air Bubbles to Measure Water Level

[opie]

There is an open thread on water level measurement, but this is a bit off topic as a different method.

Have you seen the ad occasionally in the back of a boating magazine for tank level indication without wires?

This video of mine shows how it works. I used the bubbler method in my industrial engineering career.
An application for use on our boats would work as well.

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[Idiotfool]

A few questions - first, does the system need to be air tight, or no? How high above the water level can the magnahelic be and still read accurately?

[opie]

There is no need for air tightness of tank. For example, you could measure depth of an open well or pond.
The tubing from the restrictor to the tank must be air tight. The restrictor is also a pneumatic diode, not allowing air back, so the tubing from restrictor to air source can have slow leak. For example, my old air bulb I squeeze has cracks in it.
The tubing from tank can be high or low, it doesn't care. The sensor could be 20 feet or more above tank or below tank. And the tubing could be 50 feet away from tank.
Also, an electronic sensor like the MXP could be used with an Arduino or other microprocessor instead of the Magnahelic. Note: sensor is differental pressure. You could use non-differential (gage) but I find dp to be more accurate in such small measurements. But, there are so many ranges to choose from if you want electronic. [url]https://www.nxp.com/products/sensors/pr ... 0KPA#/[url]

[Russ]

Very interesting! Seems so simple also.

Thanks for the video explaination.

[Jimmyt]

Very nice! Thanks for posting.

[opie]

I was thinking that a small aquarium air pump might work as air supply. Since the pneumatic restrictor/diode locks air in for a while, the pump could be on a program to cycle on for a few seconds several times an hour when viewing is necessary.

[Inquisitor]

Using Arduino type electronics and an absolute pressure sensor (say BMP280... IF it could be water proofed) could be put into the bottom of the tank and depth calculated. In any of these methods (ultrasonic sonar, Bubbler, digital pressure gauge) we're determining only the depth. Still some calibration/conversion would be required to convert to how many gallons/liters are in the tank. Or in the case of the Bubbler, a chart or simply using a Sharpie and writing the equivalent volume on the meter face. Many ways to tackle this problem. Certainly this Bubbler method is academically interesting, and requires no electricity. Just hand pump, take a reading and convert to gallons. Plenty good enough!