Without the HI manual, you might use outdated roughness or ignore temperature effects on viscosity, leading to a 20% error.
Beyond raw physics, the manual played a pivotal role in the economic design of piping systems. The relationship between pipe size and cost is inverse regarding capital expenditure and operational expenditure. A smaller pipe is cheaper to purchase and install, but the higher velocity causes greater friction loss, requiring a more powerful, expensive pump and higher energy bills. A larger pipe has a higher upfront cost but lower operational costs.