: Includes a force coil, a force-balance spring, a beam/flapper assembly, and a nozzle/relay system. 2. Installation Guidelines
Unlike generic positioner guides, the Fisher 3590 manual provides , failure mode behavior (air-to-open vs. air-to-close), and environmental considerations (low-temperature, corrosive, or dirty service). It also includes critical safety warnings regarding supply pressure limits and venting.
The Fisher 3590 is a pneumatic, force-balance, field-reversible positioner. Its primary function is to compare a pneumatic input signal (typically 3-15 psi or 3-27 psi) with the actual valve stem position. It then supplies or exhausts supply pressure to the actuator to maintain the exact position commanded.