external fuel level sensor

i am looking for an external fuel level sensor or the methodology to make such sensor.
kindly respond to the email with any creative ideas

Give more information on the tank setup.



Fuel tank? Vehicle? Domestic kerosene heating oil tank? Petrol is a no-no for all the obvious reasons. In UK, regulations forbid more than 10-litres stored.
Assuming heating oil tank, have a look at commercial wireless tank contents kit - might not be worth doing it from scratch.
However, large commercial tanks might use ultrasonic head (no-contact); external sight glass with some sort of optical or magnetic sensors - a lot depends on the accuracy and resolution you need i.e. full or empty? 99.9-litres? ; immersible float switches; pressure tube; optical (reflection off surface or floating reflector - I have used bike reflectors to IR detectors well over 4-metres); very old and well-tried method of float in tank, steel wire rope over pulley to weighted indicator on the outside - possible lever crank to potentiometer?

Use the forum if you want a reply, not e-mail

The photograph in the attachment shows a capacitor made out of metal plates.the width of the plate is 120mm and the height is 150mm,length is 120mm.
The metal plate actually encloses a plastic container.
Can this type of system exist?
If so kindly tell me the value of voltage if the plastic container contains gasoline/petrol.

It's not clear to me what the system you're describing is, nor what parameter you're asking about...

I can't imagine anything like what you described that would act as a practical capacitor. I mean, it sounds like you're describing 2 metal plates 120mm x 150mm, 120mm apart. That's going to have negligible capacitance, because the plates are so far apart...

Are you looking at a real device and trying to figure out what it is? If so, got a picture?

This is a joke, right? You have a voltage E, a resistance R, no dimensions for the plates in terms of their size or distance apart, and you want to know what the voltage is?

I am presuming this is related to http://forum.arduino.cc/index.php?topic=307757

Why don't you just say you are trying to measure fuel level rather than this sort of question?

The photograph in the attachment shows a capacitor made out of metal plates ...

It shows no such thing. It shows a bit of paper with a diagram on it.

This might clear things up.

Can you measure fuel level like that...? Cars use float sensors (like the ones in toilet tanks), however crude that sounds.

Man in a rowing boat in the middle of a lake throws a stone overboard.
Will the lake level rise or fall.

Seems your teacher wants you to solve a similar problem.

Two plates with something in between is a capacitor.
Same thing with something else in between is a different value capacitor.

If capacitance changes (and nothing else changes), the voltage on that cap changes.
I know someone who helped developing a flow sensor with that principle.

The metal plate actually encloses a plastic container.

Then it’s not a capacitor. It’s a short circuit.

Yes, that would work, subject to a couple of limitations.

Firstly, the actual capacitance is quite small, in the order of picofarads. Nevertheless, the Arduino is capable of discerning such values using the "capsense" library.

Secondly, any disturbance nearby, including manually handling the container in any way, or an adjacent container or in fact any object within about 30cm, would invalidate the reading unless you had a shield (metal mesh) immovably fixed and completely surrounding at least 10 cm clear of the container.

Do you want to do that?

I see that a Google search for "capacitive fuel level sensor" is quite rewarding. :slight_smile:

Somewhere in this forum not long ago there was a similar request to this, I pointed out that Ford in Australia back in 1983 were using capacitive fuel level senders in their cars.

So try google...

Tom... :slight_smile:

Man in a rowing boat in the middle of a lake throws a stone overboard.
Will the lake level rise or fall.

Is it a pummice stone?


Depends on the density of the rock.

Rock in boat, boat displacement and lake height depends on MASS of rock.

Rock in lake and out of boat, lake height depends on loss of rock MASS in boat, and increase in rock VOLUME in lake.

That is if rock is denser than water.

Tom..... :slight_smile:
Go on shoot me down, first coffee of the day....

Haha, I though eveyone knew that science question.

10 points for TomGeorge.
And 5 points for smartass MarkT.

Lake level will fall, because 'volume of displaced water' was more than 'volume of rock'.

level sensor - http://www.sparkfun.com/products/10221 - check datasheet for fuel resistance