The Darcy-Weisbach equation: can still be used to determine the head loss due to friction but f now depends upon the Reynolds number (Re) and the relative roughness (e/D); see the MOODY DIAGRAM
Example
Determine the head loss due to flow of 100 litres/s of glycerine at 20C through a 100m length of 20cm diameter pipe made of cast iron. Rework the problem for the case when the working fluid is water.
(see Table A2, p.759, Text)
(see Fig. A.2, p.763, Text)
(see Handout)
can still be used to determine the head loss due to friction but f now depends upon the Reynolds number (Re) and the relative roughness (e/D); 
see 
(see Table A2, p.759, Text)
(see Fig. A.2, p.763, Text)
(see Handout) 
