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I need to know the consumption of a water tap in Liters.

I'm able to know the cross-sectional area of the pipe and how long the tap is open. With these data, how can I know the consumption/volume of water that pass through the water tap?

It can be rough estimation. I can assume a maximum volume of water...

Thanks in advance!

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You're missing one variable to determine volume, e.g. velocity, or mean velocity or something like that. – Bernhard Dec 13 '12 at 11:27
You need to know the pressure of water in the pipe, and how fast water flows through the tap at that pressure. Also, it makes a difference if the pipe is long or short, narrow or large, because a long narrow pipe with water moving through it will have a pressure drop, so the pressure at the tap will be lower than at the source. – Mike Dunlavey Dec 13 '12 at 13:48

Put a 1-liter container under the tap, open the tap, and measure how long it takes to fill it.

Then divide the total time the tap will be open by the time it took to fill the 1-liter container. That tells you how many liters came out of the tap.

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moreover, there's a knob to control the tap aperture!! Your calculation will yield correct result provided the aperture is same... – Vineet Menon Dec 13 '12 at 14:29

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