Before choosing a formula it is worth knowing that in the paper on the Moody chart, Moody stated the accuracy is about ±5% for smooth pipes and ±10% for rough pipes. If more than one formula is applicable in the flow regime under consideration, the choice of formula may be influenced by one or more of the following:
*Required accuracy
*Speed of computation required
*Available computational technology:
**calculator (minimize keystrokes)
**spreadsheet (single-cell formula)
**programming/scripting language (subroutine).