Pneumatic valve positioner movement theory

when the input current increases, the torque motor of the plate spring as fulcrum, the armature is counterclockwise rotary torque, balance block is to the left, nozzles and damper gap open, back pressure drop in the nozzle. As a result, the forerunner of the pneumatic valve exhaust pneumatic valve core to the right, OUT of the output pressure rise, pneumatic diaphragm valve downward movement. Pneumatic diaphragm valve movement, through feedback lever, the transmission rod, range adjustment lever, effect on the feedback spring, with the force created by the input current balance, balance block set back to the equilibrium position. Compensation spring will exhaust pneumatic valve core action immediately feedback to balance blocks, in order to improve the stability of the closed-loop. Zero adjustment may be done by changing the zero spring tension.