Selecting the Correct Static Mixer Design

The pressure drop in a static mixer of fixed geometry is expressed as the ratio of the pressure drop through the mixer to the pressure drop through the same diameter and length of open pipe KL for laminar and KT for turbulent flow. 

In Tables 7-5 and 7-6, values of Kl and Kt are given. These values are considered good to about 15%. 

For completeness the standard pressure-drop equation for open pipe is 

Most vendors have more accurate correlations that take into account a slight Reynolds number effect in transitional and turbulent flow, and the volume fraction occupied by the mixer, which varies with mixer diameter and pressure rating. A more detailed approach is necessary for some designs that have the option for variable but similar geometry. For the most accurate pressure drop predictions, the manufacturer should always be consulted. 

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