Mirrant Oval-gear Flow Meter

Oval gear meters are displacement-type volume meters that transport defined incremental volumes in individual measuring chambers. The measuring element consists of two high precision toothed oval gears, which are driven by the flow of the medium and mesh with each other. In this way, a defined volume is transported for each rotation of the pair of oval gears. The number of rotations is a measure of the amount of fluid that has passed through the meter. The rotations are detected by a sensor element. A very precisely adjusted gear pair within the casing forms the measuring element. The in flowing medium causes the gear pair to rotate. The rotary motion is scanned by contactless sensors. Since each individual tooth generates a pulse, this results in a very high resolution. Consequently, even the smallest volumes can be measured or dosed precisely. The measurement unit contains two pick-offs that are circumferentially offset by of a tooth pitch to generate a 2 channel flow-proportional frequency signal. Suitable processing of the signal provides an greater resolution and the option to identify the flow direction. Basically, the measurement accuracy increases with increase in viscosity of the media. The oval gear flow meter comprises oval-shaped, geared rotors which rotate within a housing of specified geometry. Fluid differential pressure causes the intermeshing gears to rotate, trapping a ‘pocket’ of fluid between the gear and the outer housing and subsequently emptying the fluid pocket into the downstream flow