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Assume I have a 1m3 tank of air at 100 psi, they are going to release to a 1m3 tank which has air at 5 psi. There is a meter long pipe connect between two tanks.

How to calculate the flow speed ratio if the pipe is 1" diameter & connection at 5psi tank is also 1" and the pipe is 1" diameter and the connection at 5 psi tank is only 0.25" ??

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up vote 2 down vote accepted

It sounds as if you are describing flow through an orifice plate. In that case see this Wikipedia article for how to calculate the flow rate or Google for something like "gas flow orifice". There are various web sites with flow rate calculators e.g. this one.

We're not supposed to just give links as an answer, but the formulae for calculating the flow are quite complicated and I'm not sure what would be achieved by copying and pasting them here.

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Thanks. This is what I need. – Marco Apr 10 '13 at 14:18

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