Sunday, 22 July 2012

Head And Pressure Losses In Pipes

When a fluid flows through a pipe its energy is decreasing under the influence of the following factors:
  1.  Friction against the pipe walls. 
  2.  Viscous dissipation due to the internal friction of the flow.
So, with this freeware tool you can calculate these losses by using the Darcy and Weisbach formula, as well as the Colebrook and White equation.  In the workbook there are a lot of pipe materials to choose (aluminum, cast iron, polyethylene, PVC, etc.) and many working fluids (acetaldehyde, ethyl alcohol, heptane, water etc.). Furthermore, apart from the main sheet there is an auxiliary sheet that will help you calculate various unknown parameters (i.e. internal pipe diameter, fluid velocity and fluid viscosity).

How to do it

Step 1: Choose a pipe material from the dropdown list (yellow cell). Right below the list a recommended pipe roughness value will appear. You can accept it by pressing the button or you can fill your own value on the green cell.

Step 2: Insert the value of the internal pipe diameter. There is a button that will lead you to the auxiliary sheet, where you can calculate it in mm if the nominal pipe size (inch) and the pipe schedule are known.

Step 3: Fill the value of the pipe length in m.

Step 4: Insert the value of average fluid velocity. If fluid velocity is unknown you can use the auxiliary sheet to calculate it from the flow discharge.

Step 5: Fill the value of fluid kinematic viscosity. You can use two buttons depending on your working fluid. If the working fluid is water, you can use the auxiliary sheet to calculate water density and kinematic viscosity from its temperature. If the fluid is other than water, you can choose its properties from the dropdown list.

Step 6: Depending on the type of flow in the pipe you might have to press another button. So, if the flow is turbulent you will have to press the Solve Equation button.

If you have successfully filled all the necessary input values, at the second page of the main sheet the head and pressure losses will be calculated. At the end of the main sheet there are four units converters in case you need to convert some values from one unit to another. Moreover, if you press the Clear All Inputs button every input you inserted will be deleted.

Download it from here

This file can be opened with Office 2007 or newer. For best results, go to File -> Options -> Formulas tab and put a small value to the maximum iteration calculation change value. Please, remember to enable macros before using this file.

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Mechanical Engineer (Ph.D. cand.), M.Sc. Cranfield University, Dipl.-Ing. Aristotle University, Thessaloniki - Greece.
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