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I am new to finding sensors and not familiar with good resources to find what I need, so the answer may be simple.

I have a small tank that I am controlling the water level in. However, the depth only varies between 0-2 inches. Most sensors I have found don't have fine enough resolution to find measure changes in water level in this small of a tank. Any suggestions would be a big help.

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    \$\begingroup\$ How big is the tank exactly? You may be better off weighing the tank to determine how much volume is in it... You could use a pressure transducer, but finding one that is low range (sub 1 PSI) is difficult. What accuracy do you need? \$\endgroup\$ – Ron Beyer Aug 29 at 3:53
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    \$\begingroup\$ Do you need to measure the volume, or just determine whether it has reached a set point? For the latter, magnet+reed switch based float switches are simple and reliable. \$\endgroup\$ – Dave Tweed Aug 29 at 4:12
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    \$\begingroup\$ You can use an ultrasonic transducer mounted to the top of the tank that measures to the surface of the water, you would need a high-accuracy transducer though, like this one but it is required to be mounted about a foot off the closest measurement point. I'm not sure if that one will detect water, but I've used ultrasonics in industrial systems to measure tank volumes as long as the surface is still it works well. \$\endgroup\$ – Ron Beyer Aug 29 at 4:14
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    \$\begingroup\$ you are not measuring the height then ... you are only detecting specific levels ... use a toilet tank as your inspiration \$\endgroup\$ – jsotola Aug 29 at 4:31
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    \$\begingroup\$ You could make your own reed relays. Buy two glass read contacts and two tiny magnets. Glue the magnets to a piece of plastic/wood. If it is not a metal tank you could put the magnets+floats inside an the contacts outside so all electric parts are outside the water. \$\endgroup\$ – Oldfart Aug 29 at 4:50
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I'd suggest that if you are willing to use a small MCU you could use any of the breakouts using the ST VL6180 TOF sensor. Very cheap at around $3-4.
It uses an I2C interface and can measure from 10mm out to around 150mm. The Laser of course will penetrate water ....but you could float a target on the surface to provide a good reflector.

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