# Calculation Methods - Known Resistance

For all phase states the pressure loss across an open known resistance is given by: ΔP = 0.5 K ρ v2 where K is entered via the Input Editor. The pressure loss coefficient, K, is independent of fluid properties and so this approach can be used for all fluids and all phase states. For a more detailed discussion and explanation on the universality of loss coefficients see Miller [4]