Vacuum relief valve

1. A vacuum relief valve, comprising:

a housing with a central cavity, the housing having a system branch, a vacuum branch, a pilot branch, and an exhaust branch, each of the branches in fluid communication with the central cavity and having a respective port;

a piston assembly comprising a first disk located in the pilot branch, a second disk located adjacent the exhaust branch, and a connecting member to which the first and second disks are mounted; and

an actuator attached to a pilot seal, the actuator configured to move the pilot seal between a closed position, in which the pilot seal is positioned on and seals the pilot port, and an open position, in which the pilot seal is spaced from and does not seal the pilot port;

wherein when the pilot seal is in the closed position, the second disk is positioned on and seals the exhaust port, and when the pilot seal is in the open position, the second disk is spaced from and does not seal the exhaust port;

wherein the first disk has a surface that faces the pilot port having a first surface area, and the second disk has a surface that faces away from the exhaust port having a second surface area, and the first surface area exceeds the second surface area.

2. The valve defined in claim 1 , wherein the pilot seal contacts the first disk in moving from the closed position to the open position.

3. The valve defined in claim 1 , wherein the first disk is a lower disk and the second disk is an upper disk.

4. The valve defined in claim 1 , wherein the actuator comprises a solenoid having a sleeve and a rod that retracts into and extends from the sleeve, and wherein the pilot seal is mounted on one end of the rod.

5. The valve defined in claim 1 , wherein the pilot branch has a cavity, the exhaust branch has a cavity, and a diameter of the pilot branch cavity exceeds a diameter of the exhaust branch cavity.

6. The valve defined in claim 1 , in combination with an automated pharmaceutical dispensing machine.

7. The valve defined in claim 1 , wherein the first disk has a diameter that is slightly smaller than a diameter of the pilot cavity, such that movement of the first disk toward the pilot port is dampened.

8. The valve defined in claim 1 , wherein the second disk has a beveled edge and the exhaust port has a beveled edge that mates with the beveled lip.

9. The valve defined in claim 8 , wherein the beveled edge includes at least one metering holes.

10. A vacuum relief valve, comprising:

a housing with a central cavity, the housing having a system branch, a vacuum branch, a pilot branch, and an exhaust branch, each of the branches in fluid communication with the central cavity and having a respective port;

a piston assembly comprising a lower disk located in the pilot branch, an upper disk located adjacent the exhaust branch, and a connecting member to which the lower and upper disks are mounted; and

an actuator attached to a pilot seal, the actuator configured to move the pilot seal between a closed position, in which the pilot seal is positioned on and seals the pilot port, and an open position, in which the pilot seal is spaced from and does not seal the pilot port;

wherein when the pilot seal is in the closed position, the upper disk is positioned on and seals the exhaust port, and when the pilot seal is in the open position, the upper disk is spaced from and does not seal the exhaust port; and

wherein the pilot seal contacts the lower disk in moving from the closed position to the open position;

wherein the pilot branch has a cavity, the exhaust branch has a cavity, and a diameter of the pilot branch cavity exceeds a diameter of the exhaust branch cavity.

11. The valve defined in claim 10 , wherein the first disk has a surface that faces the pilot port having a first surface area, and the second disk has a surface that faces away from the exhaust port having a second surface area, and the first surface area exceeds the second surface area.

12. The valve defined in claim 10 , wherein the actuator comprises a solenoid having a sleeve and a rod that retracts into and extends from the sleeve, and wherein the pilot seal is mounted on one end of the rod.

13. The valve defined in claim 10 , in combination with an automated pharmaceutical dispensing machine.

14. The valve defined in claim 10 , wherein the first disk has a diameter that is slightly smaller than a diameter of the pilot cavity, such that movement of the first disk toward the pilot port is dampened.

15. The valve defined in claim 10 , wherein the second disk has a beveled edge and the exhaust port has a beveled edge that mates with the beveled lip.

16. The valve defined in claim 15 , wherein the beveled edge includes at least one metering holes.

17. A vacuum relief valve, comprising:

a housing with a central cavity, the housing having a system branch, a vacuum branch, a pilot branch, and an exhaust branch, each of the branches in fluid communication with the central cavity and having a respective port;

a piston assembly comprising a first disk located in the pilot branch, a second disk located adjacent the exhaust branch, and a connecting member to which the first and second disks are mounted; and

an actuator attached to a pilot seal, the actuator configured to move the pilot seal between a closed position, in which the pilot seal is positioned on and seals the pilot port, and an open position, in which the pilot seal is spaced from and does not seal the pilot port;

wherein when the pilot seal is in the closed position, the second disk is positioned on and seals the exhaust port, and when the pilot seal is in the open position, the second disk is spaced from and does not seal the exhaust port;

wherein the first disk has a diameter that is slightly smaller than a diameter of the pilot cavity, such that movement of the first disk toward the pilot port is dampened.