servo valve and solenoid valave

What is the difference between servo valve and solenoid valave?
What is the difference between hydraulic and pneumonic?

What is the difference between servo valve and solenoid valave?


I really dont know how to answer this one but I will try. A "servo valve" is just that servo. Is a device used to provide mechanical control at a distance.

A "solenoid valave" A solenoid valve is an electromechanically operated valve. The valve is controlled by an electric current through a solenoid Coil.

What is the difference between hydraulic and pneumonic? Hydraulic using Fluid. "
Pneumatic " how it is spelled is using air.

Pneumatic

:nodi:

Normally the therm solenoid valve is used for a digital valve (on-off), servo valve could be analog (4-20 mA,-10..+10 vdc) or digital if driven by a fieldbus.

A servo valve is a valve that has closed loop control of its position. Servo valves come in a variety of forms, including ones with solenoids.

A proportional valve is a valve that has a proportional solenoid that allows one to vary the power to the solenoid coil to vary the position of the valve from closed to 100% open. A proportional valve that has closed loop control of the position can be called a servo valve, but not all servo valves will use proportional solenoids as their driver. Some use a nozzle/flapper driven by a torque motor, some actually use a rotary motor. What makes it servo is the closed loop feedback. The closed loop feedback is not always electrical, it could be mechanical. For example one kind of hydraulic servo valve uses a stiff straight wire as a spring to apply force against a flapper.

Creative engineers have even made tradtional on/off type hydraulic valves work as a servo valve with fast sophisticated time proportioning closed loop control.