What is the appropriate method to calculate new friction loss?

The appropriate method to calculate new friction loss is based on the relationship between flow rate and friction loss in a pipe or duct system. The formula that utilizes the square of the ratio of the two flow rates provides an accurate way to account for how friction loss varies with changing flow rates.

When the flow rate through a pipe changes, the friction loss does not change linearly; instead, it changes with the square of the flow rates. This means if you have an initial flow rate (Q1) and a new flow rate (Q2), the new friction loss can be calculated by multiplying the existing friction loss by the square of the ratio of the new flow rate to the original flow rate ((Q2/Q1)^2).

This reflects how fluid dynamics principles dictate that friction loss increases as flow increases due to factors such as turbulence and viscosity. Therefore, if the flow rate doubles, for example, the friction loss will increase by a factor of four, illustrating the squared relationship.

Understanding this principle is crucial for accurate calculations in industrial hygiene contexts, ensuring that systems are designed and operated safely and effectively, taking into account how variations in flow can significantly impact pressure drops and associated hazards.