Abstract: A positive displacement flow meter includes a pair of smooth oval shaped rotors mounted to a pair of spaced apart rotatable shafts contained within a sealed housing. The rotatable shafts penetrate the measuring chamber and have a pair of toothed, oval shaped timing gears located in a separate gear cavity chamber which are responsible for synchronizing and maintaining the relative orientation of the smooth faced rotors with respect to one another. The fluid that is being metered forms seals between the rotating surfaces of the rotors, as well as between the rotors and the wall of rotor chamber, thus the inlet and outlet plenums are physically isolated and are consequently not in direct communication at any point during the rotation cycle of the rotors. Thus, each rotation of the rotors results in the transport of a precise and known volume of fluid from the inlet plenum to the outlet plenum.