Flow meter systems and methods providing configurable functionality

A flow meter system for detecting the flow of a fluid between an inlet and an outlet. A top plate is coupled to the inlet and the outlet and a sensor is configured to detect the fluid flowing therebetween. A main module is coupled between the inlet and the outlet and has a main rotor configured to be rotated by the fluid flowing through the main module. An output shaft is coupled to the main rotor such that rotation of the main rotor causes rotation of the output shaft. A first spacer is removably coupled between the main module and the outlet. The first spacer is rotorless. The top plate defines an opening that receives the output shaft. The first spacer ensures alignment between the output shaft and the opening defined in the top plate. The sensor senses rotation of the output shaft to detect the flow of fluid.