Restriction Orifice Sizing This is a sample of the Restriction Orifice Sizing calculator. To access the working calculator, please sign up for free membership trial. Restriction Orifice for single phase flow. Mass flowrate kg/hr Density kg/m3 Cp kcal/kmol-0C Cp/Cv (γ) Adiabatic Index Inlet Pressure barg Outlet Pressure barg Critical Pressure bara Coefficient K Orifice diameter inches Orifice area sq. inch Login Username or Email: Password: signup now | forgot password? Remember Me Sign up for free if you are not a member already.