# Pressure and Flow in a pipeline

1. May 30, 2015

### Anika

I have a 4inch pipe and I know the pressure at the start of the pipe is 4 bar. How do you calculate the flow rate?

2. May 30, 2015

### SteamKing

Staff Emeritus
You're going to need to know something about the pressure in the pipe downstream. It also makes a difference what is flowing within the pipe.

3. May 30, 2015

### Anika

Thank you. That is what I thought. I know it is water and that the pipe is connected to a 4bar line that supplies the water to this pipe system. The tie-in between the two lines is at a height of 4m.

4. May 30, 2015

### SteamKing

Staff Emeritus
Still not enough information.

Look, you could take an isolated pipe and pressurize it to 4 bar. There would be no flow, but the pressure inside the pipe would still be 4 bar.

If you are not familiar with the Bernoulli equation, perhaps this will help:

http://www.princeton.edu/~asmits/Bicycle_web/Bernoulli.html

Because this is water in a pipe, there will be friction, which the Bernoulli equation can be modified to include.

5. Jun 2, 2015