Abstract
Where a positive displacement meter is used to measure a fluid at very low flow rate, discharge volume per rotor revolution should be reduced. Volume reduction is achieved by downsizing the rotors in a homothetic way or by reducing the thickness of the rotors themselves while keeping the teeth profile as they are. Decided to be employed, in the course of engineering development of peripheral devices for fuel batteries for household use, was flow meters for modified water, whose thickness of rotors are reduced.
