velocity in force main

[vodeni]

In your opinion is 3 ft/s for an extended periods of time in a force main "good enough" velocity to prevent settling of sewage with an average solids content of about 120 mg/l?

 

[jgailla]

10 States Standards says minimum velocity in a force main to prevent solids depostion should be at least 2 ft/s (42.38, 48.1). Considerations of abnormal fluid characteristics or local regulations may make this higher.

 

[Artisi]

Sure it's "good enough", but remember, increased velocity means increased friction loss - more head against the pump or increased fall if a gravity system.
When selecting the right velocity for a pipeline "good enough" shouldn't enter the equation - in your case you need to consider solids settlement and the total head loss or fall of the pipeline.