Calculation of Pressure Regulators for liquids   Calculating the nominal diameter To keep pressure drop and noise within acceptable limits, certain flow velocities in the pipelines should not be exceeded e.g. suction side of centrifugal pumps 2 m/s suction side of reciprocating pumps 1 m/s delivery side of pumps 5 m/s local drinking water supplies 1 m/s water or fuel trunk pipelines 3 m/s high-viscosity liquids 1 m/s Pipeline diameters can be calculated as follows: d Pipeline Diameter mm Q Volume Flow m³/h w Flow Velocity m/s If in our example we permit a maximum flow velocity of 2 m/s, the required pipeline diameter will be = 35,2 mm In this case we would select a pipe of 40 mm nominal diameter (DN 40). For a given pipeline diameter the flow velocity can be calculated as follows: In our example the flow velocity for a DN 40 pipeline and a flow rate of 7m³/h would be m/s For certain operating conditions a control valve may be selected whose nominal diameter is one or two sizes smaller than the nominal pipeline diameter; this applies especially to valves with sense line. Continue Liquids Gases Steam   Kv-value   Kv-value   Kv-value   Nominal diameter   Nominal diameter   Nominal diameter   Valve selection   Valve selection   Valve selection download the PDF-file: Calculation of pressure regulators / PDF (156 kb)