How to Calculate Nitrogen Purge Velocity in Fixed Volume Tanks?

[bluesman4509]

This is not homework, but a problem from work.

If 4 tanks with fixed 90m^3 volume contained Nitrogen gas at 701.3 kPag were purged to 131.3 kPag through a 100mm pipe how would I work out the velocity/volumetric flow rate of the output?

Thanks

 

[Mech_Engineer]

As in similar threads, this problem is more difficult to solve than you might first think...

Here's a discussion on the subject of a pressure vessel depressurizing through an orifice:
https://www.physicsforums.com/showthread.php?t=363205

 

[mugaliens]

The velocity isn't dependent only upon the fluid (pressure, viscosity, density), and not just on the diameter of the 100mm pipe, either, but also the length of the tube, it's roughness, and the entry geometry (exit, not so much provided its flush or free air). Is the tube's entrance flush with the interior of the tank, or in free air?

 

[bluesman4509]

Thanks all for the pointers,

mugsliens I've completed a subject in fluid mechanics that only looked at incompressible fluids so would I be correct in saying that major (friction) and minor (inlet/outlet exspansions) head losses relate smilarly in compressible fluids?

I will receive data from some flow meters soon, since I read in another post that I would need to consider the change in temp. through the pipe I guess introducing measured data would make the theoretical calc useless anyways.