The FQB3 is an electronic mass flow controller that incorporates an integral mechanical flow amplifier to produce flow rates up to 30 SCFM. From the factory, the FQB3 mass flow controller is married to an F-series high speed mass flow transducer. A set-point command to the FQB3 controller causes the electronic flow control circuit to open the mechanical flow amplifier until the mass flow rate of air detected by the F-series flow transducer matches the electronic set-point. The loop is always closed around the flow of air independent of the required pressures.