Max Flow through a pipe

[phex]

The easiest things to calculate are often the most difficult to find. i'm feeling rather stupid right now, but can't help asking that question.

I'm in the process of sizing instrumentation for a benzene recovery process. out customer requires a hydrocarbon drain to be present, even though we can't use it due to solvent contamination of hc slop. The Drain header needs to be present nonetheless as well as sized correctly. now i found the remark "to be sized for max gravity flow" on this 4" line.

please help, how am i to calcu´late this "max gravity flow"? thanks for bothering,

chris

 

[phex]

never mind. found the solution to this one.

 

[friartuck]

you need something called the chezy equation. From memory it is something like

v=C x sq.rt M x I

C is a constant depending on the pipe type, typically 55.

M is the hydraulic mean depth and I is the fall i.e. 1 in a 100 etc.

Apologies if this equation is slightly out, but I am recalling it from 20 years ago a t college.

look for Chezy on the web

Drapes

ps. there are drainage tables published by drainage companies which give flow rates for water at particular inclinations, they might be able to assist

ciao

Drapes