Fisher 3582i Electro-Pneumatic Positioner with 4-20 mA DC Input for Diaphragm-Actuated Modulating Control Valves

Product Overview

The Fisher 3582i is an electro-pneumatic valve positioner designed for diaphragm-actuated, sliding-stem control valves. It combines a 582i electro-pneumatic converter with a 3582 pneumatic positioner. The converter accepts a 4-20 mA DC signal and produces a proportional pneumatic output through a nozzle/flapper system. This pneumatic signal then drives the positioner stage, which adjusts actuator supply pressure to hold the valve stem at the position commanded by the input signal.

The unit is known for accuracy, fast response, and tolerance to plant vibration. It consumes little air in steady state, supporting efficient operation. The modular design allows a 582i converter to be added to an existing 3582 pneumatic positioner in the field, converting it to electro-pneumatic operation.

Zero and span are adjustable with a screwdriver and spanner once the cover is removed. Direct and reverse action can be switched in the field. Supply pressure and valve load variations have minimal effect on performance. The case and internal materials resist harsh conditions, and bleed air purges internal parts for extra protection.

Technical Specifications

Application Industry

The 3582i is used in process industries with diaphragm-actuated sliding-stem control valves. It handles flow, pressure, temperature, and level control. The adjustable zero and span range covers all standard input signals, including split ranges. One positioner family supports many applications, simplifying spare parts inventory plant-wide.

Common Problems

• Positioner does not respond to input signal: Check supply pressure and pneumatic connections. Verify that the nozzle/flapper assembly is not clogged and that the relay is functioning.

• Valve stem position does not match input signal: Check zero and span calibration. Verify that the cam position matches the actuator travel and action.

• Erratic operation or oscillation: Inspect for air leaks in tubing and fittings. Check for excessive friction in the valve packing or actuator.

• Supply pressure fluctuations affect position: Confirm supply pressure is stable and within the recommended range. The 3582i is designed to minimize the effect of supply pressure changes, but extreme fluctuations may still cause issues.

Replacement Models

The 3582i is a legacy pneumatic positioner design. For new installations requiring digital communication and diagnostics, the DVC6200 or DVC2000 digital valve controllers are the modern equivalents from the same product line. The 582i converter can be field-installed on an existing 3582 pneumatic positioner to upgrade it to a 3582i configuration, though this may require changing positioner mounting and input signal range. For cross-vendor alternatives, verify actuator mounting, travel range, and input signal compatibility before ordering.