01 left spring stiffness, N/mm 600 spring force at zero displacement, N 30 coefficient of viscous friction, N/(m/s) 1000 right spring rate, N/m 300000 piston diameter, mm 10 rod diameter, mm 3 left equivalent orifice
diameter, mm 1.
Vortex meters for example, can produce a pressure drop of anywhere between low tens to low hundreds of millibars for a similar measurement system, while the pressure drop across an equivalent orifice
plate can be even higher.
If this hydraulic force were unopposed, the element would shift to wide open position and fluid would flow through the control valve with very low pressure drop -- just the equivalent orifice
drop across the valve flow path.