Hydraulic Calcs for Storm Pipe Profile Label - Part 1

Well today was a pretty good day. My favorite team Notre Dame lost but at least my Texas Longhorns won :) Anyways, I was playing around with pipe labels today and notice a few new features for pipe label expression. Now you have an option to add items such as: flow rate, Darcy Weisbach factor, Hazen William Coefficient, energy grade lines, hydraulic grade lines, manning coefficien,...etc. So I decide to try to create a pipe profile label that would give my pipe capacity, velocity, depth of flow, friction slope and velocity head.

In this post I will show you how to create a profile pipe label that will calculate pipe capacity for you. First you will need to create 5 new expression. (PipeArea, WettedPerimeter, K (conveyance factor), HydRadius and PipeCapacity. Below are the 5 expressions I created and formulas I used to create this label. (You can named these expression to whatever you like or makes sense to you) After I created my label, I started changing the pipe slope and size to varify that I got the same information that FlowMaster gave me, which it did.

1. PipeArea = (pipe radius)^2 * pi (3.14)
2. Wetted Perimeter = pipe dia. * pi (3.14)
3. HydRadius = PipeArea / Wetted Perimeter
4. K = 1.48/n * PipeArea * HydRadius^0.66  (With some rounding, I used 114.3 for my (1.486/n) n = pipe coefficien which is 0.13
5. PipeCapacity = K * (pipe slope)^0.5
6. Then I created a simple pipe label style that would display the pipe capacity based of the expression we just created. See images below.

It's important the direction of the your pipe flow. If you get question ???? switch the pipe flow direction in the pipe properties.

 RCP Pipe Area 

RCP Wetted Perimeter

RCP Flowrate

RCP Full Flow Velocity

RCP K

RCP Hydraulic Radius

RCP Pipe Capacity

RCP Friction Slope

Once you finish creating the pipe expressions then created a pipe label that uses these expressions.