Brooks® Oval Flowmeters, BM Oval Series BM01 and BM020 pages

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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.