In this work, we present a set of rules that transforms the model of Inverse Response Second Order Plus Dead Time Process (IRSODT) and reduces it to a First Order Plus Dead Time (FOPDT) model. We describe the design process for the proposed rules, where we use Dimensional Analysis Techniques and Design of Experiments (DOE). We analyze and compare our rules with those proposed by Taylor, and those proposed by Skogestad. Finally, we use our rules to tune a Sliding Mode Control (SMC) that uses a FOPDT model and we presented some performance indexes. © 2020 IEEE.