In a pressure reducing valve, the two upper operating chambers are separated by which component?

• A. Flexible, reinforced diaphragm
• B. Rigid metal plate
• C. Elastomeric gasket
• D. Piston and Cylinder

Answer: (A)

A flexible, reinforced diaphragm separates the two upper chambers. This diaphragm acts as a pressure‑sensitive barrier, transmitting the upstream pressure signal to the valve actuator while keeping the downstream side isolated, so the downstream pressure can be regulated. Its flexibility allows it to deflect with pressure changes and move the valve stem to adjust opening, maintaining the desired set downstream pressure; the reinforcement provides the strength to withstand system pressures. A rigid metal plate wouldn’t permit the required movement, an elastomeric gasket is used for sealing rather than forming the pressure-sensing barrier, and a piston and cylinder describes a different actuator design.