Resources, Tools and Basic Information for Engineering and Design of Technical Applications!
mobile - visible on handheld devices - alternatively go to www.engineeringtoolbox.com!
Engineering ToolBox > Valve Authority

The valve authority can be expressed as
N = dpv / (dpv + dpc) (1)
where
N = valve authority
dpv = pressure drop across a full open control valve (psi, Pa, bar)
dpc = pressure drop across the circuit (psi, Pa, bar)
The valve authority should in general be in the range 0.2 to 0.5.