A method and system for data usage accounting are described herein. The hot gas may be supplied from a fired heater, a boiler, a reformer, a process air preheat furnace, a gas turbine, or the like. In other embodiment, the aging time is dynamically adjusted based on the VCC threshold level, the protocol of the flow, andor the application type of the flow. The techniques disclosed can give accurate results without requiring particular constraints on meter design. The driving unit is operable so as to drive rotation of the rotary member about the axis such that the connecting pieces are bridged selectively and electrically by the contacting regions of the rotary member for varying the speed of the induction motor.