If your process logic requires the positioner output to decrease as the input signal increases: Loosen the beam pivot assemblies.
The manual includes a troubleshooting guide to help users diagnose and resolve common issues:
Unlike digital positioners, the 3590 requires periodic mechanical maintenance. fisher 3590 valve positioner manual
| Component | Function | |-----------|----------| | | Nozzle-flapper mechanism to convert small signal changes to pressure. | | Nozzle | Receives supply air; backpressure changes move the pilot relay. | | Range spring | Provides force balance against the input signal diaphragm. | | Feedback spring | Connects to the valve stem via a cam/arm; closes the loop. | | Pilot relay | Amplifies nozzle pressure to high flow output. | | Proportional cam | Defines the relationship between travel and feedback. | | Zero adjustment screw | Sets the starting point (signal vs. position). | | Span adjustment screw | Sets the travel range for a given input span. |
The 3590 series typically includes the standard , 3590S , and 3590ST models. Input Signal: 4 to 20 mA DC. Internal Resistance: Approximately 300 Ohms. Supply Pressure: Maximum 50 psig. If your process logic requires the positioner output
Because zero and span adjustments are interactive, changing the span will shift the zero point. Repeat steps 1 and 2 iteratively until the valve stroke precisely matches the 0% and 100% signal marks. Reversing the Positioner Action
The Fisher 3590 series consists of pneumatic and electro-pneumatic positioners designed for use with diaphragm-actuated valves. They use a feedback linkage to sense the actual valve position and compare it to the input signal from the control system. Key Components Receives the 4-20mA or pneumatic signal. | | Nozzle | Receives supply air; backpressure
The Fisher 3590 valve positioner is a reliable, high-performance device that, when properly understood and maintained, provides years of accurate control. This guide covers the essential tasks—from locating the and understanding specifications, to installing, calibrating, troubleshooting, and maintaining the device.
Always disconnect or bypass process flow before installing the positioner.
The Fisher 3590 relies on mechanical zero and span adjustments to calibrate the valve travel relative to the input signal (typically 4–20 mA or 3–15 psi).