pipe velocities

[bloudup008]

I am busy with fire pump design
what velocities do you recomend for:
-suction pipe (1.5m/s)
-suction manifold(1.5m/s)
-discharge piping (2m/s)
-discharge manifold(2m/s)?

 

[itdepends]

It will depend on the size of the piping to some extent. Being firewater you won't have to worry about erosion unless you really go hard with velocities.

The bigger the pipe- the faster the average velocity you can tolerate. The limitations on flow through a pipe are generally erosion and pressure loss- as you go up in pipe diameter you have a larger "core" of faster moving material and lower wall velocities.

I'd suggest trying some programs to calculate pressure loss over a conceptual piping run. Play with the pipe size and velocity until you get a feel for what flow is acceptable at different pipe sizes. Remember to include fittings in the piping run.

But as a start anyway- I'd suggest you could run your discharge velocities up to 2.5-3.0m/s with no real problems- as long as it's 200NB or larger

Cheers.

 

[BigInch]

Itdepends, is on the right track. 3m/s should be fine and even a bit low for firewater service. I could suggest you go higher, if your overall pressure drops remains within acceptable ranges AND you complement the steady state analysis with a transient surge "water hammer" study.

http://virtualpipeline.spaces.msn.com