The pipe friction coefficient look-up table (viz. HW/DW Roughness Coefficient Table) - a list of typical HW/DW coefficients for pipes of a certain diameter range, material and age - is accessible from the System tab of the Model Settings box.
In order to select a specific pipe friction coefficient, the procedure is as follows:
1. Place the cursor on the coefficient to be selected.
2. Click on OK, and the appropriate coefficient will be selected and entered into the Hazen-Williams (HW) or Darcy-Weisbach (DW) Coeff field.
See also Appendix B for more information on pipe roughness coefficients.