# Pressure and flow rate relationship

1. Oct 26, 2013

### mfholbac

If I 8000 gpm flowing in a pipe, and know that pressure of the water is 55psig, will the pressure be 27.5psig if the flow rate through the same pipe drops to 4000gpm.

2. Oct 26, 2013

### Staff: Mentor

Hi mfholbac. Welcome to Physics Forums.

I assume you mean that the inlet pressure is 55 psig, and the outlet is into the atmosphere at 0 psig. If the flow is turbulent, which I assume will be the case in your system, then the pressure will drop more that just half-way, but a little less than 3/4 of the way.

Chet

3. Dec 8, 2015

### MANPREET SINGH

Sir, Kindly let me know how to calculate flow rate (cfm or Litre/m) of air flowing through a pipe of 12 mm dia from a reservoir at pressure 7 kg/cm2 to atmosphere.

i.e ;- how much volume of compressed air could pass within a minute through a "X" mm dia pipe from a constant pressure (7 kg/cm2)

4. Dec 8, 2015

### Staff: Mentor

This thread is over 2 years old, with no new responses. Please start a new thread. I am closing this one.

Please put your new thread in one of the homework forums, and use the template. Also, please do some literature search on your own before posting, to get an idea how to address a problem like this. The homework template will ask you to show your thinking and effort so far.

Chet