External tank level sensing via density ?

I stumbled across an interesting sensor that I cant seem to find any information on. The way I understand it is that this strip sensor is applied tithe outside of a tank and the resistance changes as the level changes inside the tank... It says the resistance increases as level increases from 50 - 500 ohms. Somehow it can tell the difference in density inside the tank, supposedly works on propane as well...

Does anyone know anything more about this ?

I found another system I suspect uses the same method... Looks to be more like a capacitance type system than a density based system as I had read in an article...

http://www.sailorssolutions.com/index.asp?page=ProductDetails&Item=TM03

So indeed it is capacitance... A simple 555 circuit may work well here ! :slight_smile:

The density of water does not change.

density of water does not change

True.. within the context of the discussion...

But I bet water on the other side of the tank wall changes the capacitative environment at that point on the sensor... perhaps because(?) of the density of the substance there, water, rather than air. Or some other property of the two, but, bottom line, idea for sensing level MIGHT work...

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The OP may have heard of level sensor which work based on the OPTICAL density of fluids, and their effect on beams of light bouncing... or not bouncing... around inside prisms. This is used in ink jet cartridges, Canon for one. But the prism has to be in direct contact with the contents of the tank.

hotshotharry:
I stumbled across an interesting sensor that I cant seem to find any information on. The way I understand it is that this strip sensor is applied tithe outside of a tank and the resistance changes as the level changes inside the tank... It says the resistance increases as level increases from 50 - 500 ohms. Somehow it can tell the difference in density inside the tank, supposedly works on propane as well...

Holding Tanks Solution - Garnet Instruments

Does anyone know anything more about this ?

it can not see thru metal dude