# Is it possible to build something that can measure water and oil in a tank with out being in the tank?

Say you have water and oil in tank....Is there any thing out there that can tell me how much water is in the tank and how much oil is in the tank???

• What's the tank made of? Is it transparent? – Oli Glaser Aug 13 '12 at 7:03
• Without you going in the tank? I would say, send your brother in :-). (Sorry, couldn't resist) – stevenvh Aug 13 '12 at 7:04
• Do you have a tank with both water and oil, and you want to know both how much water and how much oil? And how big a tank, and to which accuracy? – Wouter van Ooijen Aug 13 '12 at 7:20
• Please provide a clear and more detailed description of what you mean by "water & oil". Do you simply want the total combined amount? Are they mixed together (an emulsion) or in 2 layers? Water on top or oil on top? - depends on oil SG. What sort of oil is it. – Russell McMahon Aug 13 '12 at 7:39
• If we know the type of oil, we can think of something. – Ktc Aug 13 '12 at 8:12

Since water will eventually separate from the oil if the fluid in the tank is kept still, then it is easy to use ultrasonic sensor.

E.g. You have a tank, that has water and oil already separated after some amount of time:

|          |
|   water  |
|__________|
|          |
|    oil   |
|__________|


In this case You'd clearly see a reflection of sound wave from the conjunction of water and oil. Knowing the speed of sound in the oil and water You can measure the height and finally find the numbers You need.

• Actually, you have live preview right below the text box where you type the answer. – AndrejaKo Aug 13 '12 at 8:01
• If you take a moment to read the markdown help you'll know how to get ASCII art like I inserted into your answer. – stevenvh Aug 13 '12 at 8:07
• Interesting approach. I wonder if we can use conductivity in a similar way. – Ktc Aug 13 '12 at 8:13
• Unless it's crude oil it's more likely that the oil will be on top. – stevenvh Aug 13 '12 at 8:16
• True, more likely oil will be on the top, but anyway, got the idea. – Socrates Aug 13 '12 at 8:51