EP6 Electro-pneumatic Positioner

Precise pneumatic valve positioning from a 4-20 mA signal

The Spirax Sarco EP6 is a two-wire electro-pneumatic positioner for linear and rotary pneumatic valve actuators that conform to NAMUR. It compares the controller's 4-20 mA input with actual valve position and modulates the pneumatic output so valve travel follows the command signal.

EP6 can be configured for single- or double-acting service and for linear or rotary mounting. The selected mounting arrangement and linkage kit must match the actuator, valve model, size and required mounting position; the compatibility table below should be checked before ordering.

Where the Spirax Sarco EP6 fits in a control valve assembly

The positioner is intended for pneumatic modulating-valve duties where a controller provides a 4-20 mA command and repeatable actuator travel is required. Typical assemblies include compatible Spira-trol control valves and other linear or rotary valves fitted with a NAMUR-compliant pneumatic actuator. Because linkage geometry affects feedback accuracy, the actuator series, valve size, stroke and mounting position should be confirmed together rather than selecting the positioner in isolation.

For an existing installation, first identify whether the actuator is single acting or double acting and whether direct or reverse action is required. Then confirm the available instrument-air pressure, required travel and mounting-kit arrangement. This sequence helps avoid a positioner configuration that can receive the electrical signal but cannot correctly reproduce the valve's full mechanical stroke.

Selecting a Spirax Sarco EP6 configuration

• Linear actuator travel from 20 to 150 mm, or rotary travel up to 90 degrees.
• Instrument-air supply from 1.4 to 7.0 bar, regulated 5 to 10 psi above the actuator spring range.
• Required air quality: ISO 8573-1:2010 Class 3:3:2.
• IP66 enclosure with safe-area and approval-specific hazardous-area configurations available.
• Standard and high-temperature configurations have different operating limits; verify the complete ordering code and product nameplate.

Safe-area and Ex-approved configurations require separate checks. For ordinary industrial locations, confirm the enclosure, action and mounting options against the technical data. For a hazardous area, use the approval shown on the specific EP6 nameplate and follow the matching installation document; ambient-temperature limits, cable entries and certification conditions are approval-specific.

Installation and safety boundary

Commissioning requires qualified personnel, correct electrical isolation and clean, dry instrument air. Hazardous-area installations must follow the applicable EP6 approval, nameplate, certified cable-entry requirements and the full IM-P703-04 instructions. Do not apply a certification or ambient limit from one approval to another configuration.