Diaphragm valve with electronic pressure detection

1. A flush valve for a waste water system, comprising:

a valve body comprising a fluid inlet, a fluid outlet, and a main valve element extending between the fluid inlet and the fluid outlet, the main valve element adapted for movement to allow fluid flow between the fluid inlet and the fluid outlet based on a pressure differential across a portion of the main valve element;

a vent system comprising a control chamber in flow communication with the fluid inlet of the valve body and a vent outlet in flow communication with the fluid outlet of the valve body;

an electronically operated solenoid valve adapted to operate in a first mode to establish flow communication between the control chamber and the vent outlet so as to selectively vent fluid from the control chamber to the fluid outlet to establish a pressure differential across a portion of the main valve element to permit the main valve element to open for fluid flow between the fluid inlet and the fluid outlet of the valve body, and to close to prevent fluid communication between the control chamber and the vent outlet to close the main valve element, the electronically operated solenoid valve adapted to operate in a second mode to vent the control chamber to reduce the fluid pressure within the control chamber without permitting the fluid pressure within the control chamber to drop below a required pressure threshold to maintain the main valve element closed, thereby reducing build up of fluid pressure within the valve body while preventing operation of the valve;

a pressure sensor adapted to sense the fluid pressure of fluid within the vent system and produce an output signal based on the sensed pressure, wherein a high voltage threshold output signal corresponding to a predetermined pressure threshold is defined; and

a microprocessor adapted to energize the solenoid to operate in the first mode and in the second mode, wherein the microprocessor energizes the solenoid to operate in the second mode in response to the high voltage threshold sensed produced by the pressure sensor, thereby energizing the solenoid for only a limited predetermined period of time to vent the control chamber to reduce the fluid pressure within the control chamber without permitting the fluid pressure within the control chamber to drop below a required pressure threshold to maintain the main valve element closed.

2. A flush valve as in claim 1 , wherein at least a portion of the valve body is constructed of a plastic material.

3. A flush valve as in claim 1 , wherein the vent system further comprises a vent chamber in flow communication with the control chamber through a vent inlet passage extending between the control chamber and the vent chamber, and wherein the vent outlet is in flow communication with the vent chamber.

4. A flush valve as in claim 1 , wherein the pressure sensor comprises a pressure transducer.

5. A flush valve as in claim 4 , wherein the pressure transducer is connected to a control board comprising a pressure transducer control and the microprocessor.

6. A flush valve as in claim 5 , where in the control board is located on the solenoid.

7. A flush valve as in claim 5 , wherein the pressure transducer control includes a voltage amplifier.

8. A flush valve as in claim 1 , wherein the solenoid comprises a core tube in which a piston is slidable, with the core tube in flow communication with the vent system.

9. A flush valve as in claim 8 , wherein the pressure sensor extends into the core tube.

10. A flush valve as in claim 8 , including an actuator coil around at least a portion of the core tube.

11. A flush valve as in claim 10 , wherein the actuator coil comprises a first coil section and a second coil section.