Design of Gravity Lines

I need to understand the factors relavent in desigining a gravity fed pipeline. The data is as u/m:-

1. Source of water : River on a hill 120 mt vertical height.
2. Water required at bottom of the hill .
3. Slope of Hill is about 1/30
4. Qty required is about 300 GPM

I have been informed to use Mannings Formulae for designing the pipe. But the Mannings Formulae does not take into consideration the Total Length of the pipeline. In other words, as per Mannings Formulae, When Slope and GPM are Constant, the ID of the Pipeline is independent of the length of the pipeline ( or independent of Friction Lossesz due to any length of Pipeline. ) Is it true? Can I use Mannings formulae to design a Gravity Fed Pipeline? Or are there any other factors to be considered?

I have worked out the above data by applying Hazen Williams Formulae as well as Mannings Formulae. There is a huge difference in the derived results.

Can anyone clarify?

Pawan Agarwal
pagarwal@hallmark.co.in Received on Mon Jul 15 16:20:00 2002