Numerical simulations were conducted to investigate three non-standard design or non-ideal situations that may arise in the design, fabrication, and usage of PPD laminar flow elements. For the non-standard design with different numbers of capillaries in two branches, in which the numerical simulations were conducted, the pressure drop curves and differential pressure-flow relationships obtained showed minimal differences compared to the standard structure. The relative deviation between the calculated flow rate and the accurate flow rate, as determined by the pressure drop calculations, was within ±0. 4%. Additionally, the experimental data from flow rate measurements confirmed the simulation results, further demonstrating the applicability of the PPD principle to structural designs with varying numbers of capillaries in the two channels. Regarding the potential occurrence of blockages at the capillary inlets or outlets during fabrication or usage, calculations revealed the presence of nonlinear deviations in the differential pressure. Depending on the location of the blockage, either positive or negative deviations may occur. Furthermore, when there is a deviation in the capillary diameter between the two branches, the impedance characteristics of the two branches become dissimilar. This dissimilarity in flow rates and velocities within the capillaries of the two branches leads to incomplete compensation of local resistances at the inlets and outlets, causing the differential pressure-flow curve to deviate from the ideal curve. The aforementioned research findings hold valuable insights for the practical application of PPD laminar flow sensing technology.