Rigid piston valve incorporating a solenoid

A flush valve for a plumbing fixture comprising:

• a) a fluid inlet in fluid communication with a fluid source;
• b) a fluid outlet in fluid communication with a plumbing fixture;
• c) a cap positioned at an end opposite the fluid outlet;
• and
• d) a piston valve for regulating fluid flow between the fluid inlet and the fluid outlet, the piston valve comprising:
• a rigid piston comprising a disc shaped member having a central opening, an elongated hollow member that is attached to and extends down from the disc shaped member, and a piston seal;
• and
• e) a solenoid connected to the cap,
• wherein the piston seal is formed from a single article comprising a disc shaped body with a central opening and an annular skirt that is adapted to expand out toward the cap connected to the valve body and form a seal with the cap,
• wherein the annular skirt extends around an outside perimeter of both the piston seal and the disc shaped member of the rigid piston,
• wherein the rigid piston includes a by-pass orifice defined in the disc shaped member,
• wherein the rigid piston further comprises guide members that maintain an alignment of the rigid piston within the valve during operation,
• wherein the guide members extend down the length of the elongated hollow member of the rigid piston,
• wherein the rigid piston further comprises a flow ring that gauges the amount of water to be flushed during operation,
• wherein the flow ring is attached to an outer surface of the elongated hollow member of the rigid piston,
• wherein the flow ring is attached to the guide members, and
• wherein the flow ring is scallop shaped.