Moore Products Model 55 Series Two-Mode Nullmatic ControllersThe Series 55 Nullmatic Controller is a two-mode controller which operates on the pneumatic "Null" balance principle. It controls the process variable in response to an air pressure signal from the process transmitter. The Model 55 controller incorporates adjustable proportional band (gain), reset action and an integral setpoint regulator.The controller is intended to operate on an output of 3-15 psig from a pneumatic transmitter. However, it is capable of operating at any range under 45 psig. The controller output is normally 3 to 15 psig, but it may be as much as 45 psig for special purposes.