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Variable Area Flow Meters (Rotameters)

Process-proven flow meters. For maximum repeatability and reliability.

As one of the pioneering manufacturers in variable area (VA) flow meter (rotameter) technology, Brooks Instrument has created a diverse and proven portfolio of gas flow meters, installed and in use across virtually every industry. From inline to low volume flow meters  Brooks offers high-performance gas and water flow measurement instruments for your application.

This broad portfolio includes armored metal and glass tube flow meters (rotameters), each engineered to provide years of repeatable, reliable measurement of gas and liquid flow rates. They feature:

  • Reliable, easy-to-read displays on all flow meter types
  • Fail-safe inline flow indication under any circumstance
  • Integral flow controller to compensate for varying pressures
  • Materials and designs to suit multiple pressure ranges and chemical compounds
  • Field-replaceable components and custom scales
  • Integration of optional flow switches, automated valves or alarms

Trust the expertise of the Brooks Instrument team for valuable insight on the right fluid flow meter for your needs.  Talk to us for more on our range of flow meter types for gas and water, and see why Brooks Instruments leads the world in variable area flow meters.

Key Applications

  • Basic liquid (including water) or gas flow measurement
  • Rotating equipment flow measurement
  • Process analyzers
  • High-pressure flow on offshore oil platforms
  • Chemical injection
  • Purge liquid or gas metering
Brooks MT3809G variable area flow meter cutaway
MT3809 with Explosion Proof Housing, Variable Area Flow Meter -
  • Improved accuracy over plastic flow meters
  • Suitable for wider flow ranges and and more gas types
Fluid Type

Clean Gases & Liquids

Flow Range (Full Scale Capacity)
Air: 170 scfm - 280 m3n/hr
Water: 98 gpm - 22,000 l/h

1-2% FS

Max Pressure
Refer to Maximum Pressure Ratings Table in Data Sheet
121oC (250oF)
Output Type
Visual Indication
  • For use in high/low pressure and temperature applications
  • Ideal for measuring fluids in hazardous, remote areas
  • Simple design is easy to install and maintain
Fluid Type
Clean Gases, Liquids & Steam
Flow Range (Full Scale Capacity)
Air: 750 scfm - 1200 m3n/hr
Water: 440 gpm - 100,000 l/h
1-10% FS
Class 1.6 - 4 VDI/VDE
Max Pressure
1379 bar / 20,000 psig
420oC (788oF)
Output Type
Visual Indication
4 - 20mA Analog w/HART® 7
Flow Switches
Component datasource missing. Select a datasource for this component.
Component datasource missing. Select a datasource for this component.