Water pipe flow rate for drainage ditch

[skleen]

Hello

Can anyone help me with the calculation for maximum flow rate for a 300mm that will be used as a culvert to convert an open water course into this piped culvert.

I expect that the pipe will only be half full.
The fall is 1 in 100 and I need the result in litres/second to comply with our councils drainage engineers request.

Thanks in advance

 

[EightyTwo]

I searched Google and found this:

http://www.brighthubengineering.com...te-water-flow-rates-for-different-pipe-sizes/

so the sum is:

Q=0.278x100x0.3^2.63x(1/100)^0.54

where 100 is for a concrete pipe, 0.3 is the diameter in metres and (1/100) is the fall.

I get an answer of Q=0.09747m^3/S or 97.47 litres/second
That would give you a velocity in the pipe of about 1.4m/s (or 3 mph) which feels about right.

I have no idea if I am right about this - I'm an alarm engineer! The sums look good and, if you mention the Hazen Williams formula, I'm sure that the council engineer will think that you know what you're talking about! [/b]

 

[EightyTwo]

What is the world coming to? - you spend an hour and a half helping someone with a problem and you don't even get a reply, let alone a thank you!

 

[coopersim]

I appreciate this response as it's exactly the problem I'm having!