This multi-purpose, direct acting, 3-way positioning pilot is actuated by a pressure responsive diaphragm, which tends to reach equilibrium with the set spring force. The pilot directs flow and pressure between its ports:
When sensed pressure is above set point, it connects port “C” to “0″.
When sensed pressure is equal to set point, it blocks connections between all ports.
When sensed pressure is below set point, it connects port “C” with “A” and “Z”.
An integral needle valve restricts flow through port “Z”.