what is difference between Servo valve & propotionalcontrol valve
A servo valve is one type of proportional control valve where a servo motor is used to control the how far the valve is open and closed. I its simplest form there are mechanically controlled proportional valves like that standard multi-turn valve on your sink.
Niel Leon
community developer – engineering.com
i think the proportional valve you are referring to would operate of an anolgue signal, say 4 – 20 mA, 4 being fully closed and 20 being fully open and anywhere inbetween giving a proportional flow.
a servo valve will employ negative feedback to a servo controller which will interpret this as an error signal of actual flow to required flow, the controller will then either open the valve more or less to achieve the required flow, this is a continuous process which achieves highly accurate results as the valve is now self modulating.