Double Acting Positioner Description - GE Baker Hughes Masoneilan SVI FF Installation And Operation Manual

Double Acting Positioner Description

The Double Acting (DA) relay has a pair of opposed pneumatic outputs. When Output 1
delivers air to one side of the actuator, Output 2 vents air from the opposite side of the
actuator piston. The volume of air trapped in each determines the position of the actuator.
The Action (ATO or ATC) is applied with respect to Output 1. When Output 1 is connected to
deliver air to extend the actuator, the action is ATC, on a down-seating valve.
Output II
Supply
Output I
Figure 15 Air Ports on Double Acting Positioner
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