Pneumatic P controller

  • A proportional mode of operation can be achieved with the system shown.
  • Operation is understood by noting that if the input pressure increases, then the input bellows forces the flapper to rotate to close off the nozzle.
  • When this happens, the output pressure increases so that the feedback bellows exerts a force to balance that of the input bellows.
  • A balance condition then occurs when torques exerted by each about the pivot are equal.