Patent ID: 7694934

Claim:
A diaphragm valve comprising: a valve body having an inlet passage and an outlet passage; a diaphragm positioned between the inlet passage and the outlet passage, the diaphragm having a closed position where fluid flow from the inlet passage to the outlet passage is blocked and an open position where fluid flow from the inlet passage to the outlet passage is permitted; a control chamber disposed on one side of the diaphragm; a control chamber entrance passage extending from the inlet passage of the valve body to the control chamber to permit fluid to flow from the inlet passage of the valve body into the control chamber; a control chamber exit passage extending from the control chamber to permit fluid flow from the control chamber; a valve positioned to selectively permit fluid flow through the control chamber exit passage from the control chamber to the outlet passage of the valve body to control the fluid pressure in the control chamber; a screen positioned to restrict debris from passing through the inlet passage to the control chamber; a scrubber rotatable relative to the screen to remove debris from the screen; and a brake associated with the scrubber and configured for limiting the acceleration of the scrubber at or above certain speeds in order to reduce the potential for harm due to friction between the scrubber and the screen.