PaulS:
You definitely need a flow meter. It would be far easier for you to choose one that fits the application (that is, that actually could be installed and measures the volume of liquid that passes through it) and that you can get, at a fair price.We don't know what kind of liquid you are talking about, or what the flow rate is. There is a difference between measuring 100 gallons of water per week, flowing through a 2 centimeter pipe and measuring 100000 gallons of liquid propane flowing through a 20 centimeter pipe.
All flow meters operate in the same way, though, outputting a pulse after some volume of material passes through. Connect the output to an interrupt pin on an Arduino, and each time the interrupt handler is called, one unit of material has poured into the tank. The differences are what kinds of material they can handle being exposed to and what the unit of measure is.
Thank you for the quick reply PaulS, I was not expecting help this quickly so I jumped the details.
The liquid(s) in question are Water, Ethanol and/or Gasoline (petrol or benzine for the euro guys i think).
If you guessed by my nickname that its for my Dune Buggy (its not exactly a dune buggy but its as slow as one in terms of speed, but its more of a prototype) you are right.
The standalone Fuel Injection system gives me the information on how much fuel its consuming and calculates the mileage, i would "combine" that with this simple device that measures exactly how much fuel is poured into the tank.. so i could know precisely how much fuel was refueled and if any evaporated or was somehow lost in the fuel system!
I cant provide pictures or too many specific details of now because im still doing the bodywork and there are some other clever things im working on that i dont want to show it in public and risk have it copied before im even done, but i would gladly do so and credits those that helped me specially after i get the paint and livery done, great stuff for a portfolio thought.
So i now its clear that i need a Digital type of Flow Meter that can measure from very little flow as of someone slowly dropping fuel with a canister to as much as a high flow fuel pump from a Fuel Station, i dont know exactly how much flow is that but i will try to measure it today and update this info with a reply.