Valve actuator system

1. Valve actuator system, comprising:

a valve that has a valve housing at least one inlet, at least one outlet, a valve regulating element for controlling flow through the valve and that is mechanical connected to a valve actuator having at least one piston that is movable in a housing by a pressurized liquid medium in at least one direction and that is connected to the valve regulation element, the housing of the valve actuator comprising a first cavity chamber and a second cavity chamber which are separated by said at least one movable piston, which first and second chambers are connected through connecting lines and a valve arrangement to a pressure line and to a return line, the pressure line being connected to a pump, the return line being connected to a tank, and the pressurized liquid medium being a primarily incompressible medium comprised primarily of water,

wherein the valve arrangement has a magnetic coil and a slider that is movable by the magnetic coil,

wherein the at least one piston is lockable in the housing by blocking connection of the connecting lines to the pressure line and the return line by movement of the slider of the valve arrangement by said magnetic coil, whereby the piston and the valve regulating element are locked in a given position that prevents pressure fluctuations in a drug or food in said flow from moving the valve regulation element and the piston in any direction as a result of the pressurized liquid in the blocked connecting lines being essentially incompressible, and wherein the valve is a hygienic sanitary valve connected in a flow of fluid food or drug for regulating of said flow, at least surfaces of the valve in contact with the food or drug being formed of a hygienic material, which material prevents growth of bacteria or fungus.

2. Valve actuator system according to claim 1 , whereby the valve actuator is movable linearly in relation to a linear operating valve closing element.

3. Valve actuator system according to claim 1 , whereby the valve actuator is movable in relation to a rotationally operating valve closing element.

4. Valve actuator system according to claim 1 , whereby the pressure of the liquid media is mostly below 50 Bar.

5. Valve actuator system according to the claim 4 , whereby the valve actuator is adapted to open the valve when the pressurized liquid flows into the first cavity chamber, where opening the valve also activates a return spring for closing the valve when the amount of pressurized liquid in the first cavity chamber is reduced.

6. Valve actuator system according to the claim 4 , wherein at least a first actuator is adapted to perform regulation of a first valve closing element in the valve, wherein at least a second actuator is adapted to perform regulation of a second valve closing element in the valve.

7. Valve actuator system according to the claim 4 , whereby the valve actuator comprises the first cavity chamber for closing the valve when a pressurised liquid is supplied to the first cavity chamber, and the second cavity chamber for opening the valve when a pressurised liquid is supplied to the second cavity chamber, and where said at least one movable piston separates the first and second cavity chamber.

8. Valve actuator system according to the claim 7 , whereby the magnetic coil is electrically activated for moving the slider between a first position where flow to and from the valve actuator is closed, a second position for pressurising the first cavity chamber and reducing the pressure in the second cavity in the valve actuator, and a third position for pressurising the second cavity and reducing the pressure in the first cavity chamber.

9. Valve actuator system according to the claim 8 , whereby the magnetic coil is electrically activated by pulse-width modulation.

10. Valve actuator system according to the claim 7 , wherein the valve actuator piston is lockable by discontinuing the flow of pressurised liquid into and out of the first and second chambers.

11. Method for operating a sanitary valve positioned in a flow of drug or food, which valve at least performs regulation of the flow from an inlet to an outlet of the valve by a valve regulating element,

which valve regulating element is operated by at least one actuator, which actuator comprises a first and a second chamber, which chambers are separated by a valve actuator piston,

which valve actuating piston is activated by a pressurized liquid supplied from a pressure source into the first and second chambers, via liquid lines and valve arrangement having a magnetic coil and a slider that is movable by the magnetic coil,

wherein pressure in the first and second chambers is regulated through the valve arrangement regulating the flow from a pressure line and to a return line, which pressure line is connected to a pump, and which return line is connected to a tank,

wherein the pressurized liquid is an essentially incompressible liquid comprising mostly water,

wherein the method comprises the step operating the magnetic coil so as to move the slider into a position blocking the liquid lines towards the first and second chambers at both sides of the piston in order to lock the position of the piston and the valve regulating element,

wherein the valve regulating element is locked in a manner which prevents pressure fluctuations in the drug or food from influencing the position of the valve regulating element as a result of the pressurized liquid in the blocked liquid lines being essentially incompressible, and

wherein at least surfaces of the valve in contact with food or drug in said flow being formed of a hygienic material that prevents growth of bacteria or fungus inside the valve.