Brooks® Oval Flowmeters, BM Oval Series BM01 and BM02 - Brooks Instrument - #1

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1 Brooks® Models BM01 and BM02 Data Sheet DS-PD-BM 01-02-eng March, 2008 Brooks® Oval Flowmeters, BM Oval Series BM01 and BM02 FEATURES • Low flow measurement, 0.53 to 132 GPH (2 to 500 LPH) • Very low pressure drop • Viscosity to 1000 Cp (Centipoise) • High Accuracy, 1% rate or better • 0.03% repeatability • Only two moving parts • Reed or solid state Hall Effect Switch • ¼ inch female NPT standard • Available in PPS or 316 Stainless Steel (Hastelloy® C shaft option) DESCRIPTION The Brooks BM01 and BM02 are low flow positive displacement oval flowmeters designed for applications requiring the high accuracy measurement of clean liquids with viscosities less than 1000 Cp. Units are available with a pulse output from a Reed switch or solid state Hall effect switch for remote registration and/or totalization. PRINCIPLE OF OPERATION The oval meter is a positive displacement meter. As the fluid being measured passes through the meter, it rotates 2 oval gears in a measuring chamber to displace a precision volume of fluid. A sensor detects the gear rotation to determine displaced volume and flow rate. Fluid pressure rotates the oval gears, Figure 1. In position 1, the fluid exerts a clockwise driving force on Gear A. Typical BM01 and BM02 Figure 1 Principle of Operation Chart There is no net driving force on Gear B. It is perpendicular to the flow so the fluid forces are balanced around the shaft. As the gears rotate to position 2, the fluid begins to exert a force on Gear B. At position 3, all the driving force is on Gear B. This alternating driving force provides a smooth rotation of almost constant torque. The meter design minimizes the slippage between the gears and the measuring chamber wall. As a result, the oval meter is less affected than other designs by the liquid's viscosity and lubricity.