Smart Measurement Variable Area Flowmeter

Variable Area Measuring


Variable area flowmeters are simple and versatile devices that operate at a relatively constant pressure drop and measure the flow of liquids, gases, and steam. Variable Area (VA) flowmeters make use of a float, piston or vane placed inside a flow body, which changes position in response to changes in flow rate of the measure fluid media. The position of the float, piston or vane provides a direct visual indication of flow rate. Either the force of gravity or a spring is used to return the float to its resting position when the flow lessens.  For a more detailed discussion of the principle of operation, please go to:

SmartmeasurementTM’ s ALVAMT Variable Area flow meter is of the spring operated variety, which allows the meter to be mounted in either horizontal or vertical orientations. The ALVAMT makes use of rugged, metal tube construction making it ideal for high pressure, high temperature and other demanding flow applications where safety is a concern.  Features include mechanical readouts for use in locations where power is not available or in hazardous areas; analog and digital LCD local display options, multiple process connection options; several different materials of construction for metering of aggressive fluids and corrosion resistance; and HART enabled 4-20mA output to allow for remote monitoring and control.

Metal Tube Variable Area Flow Meter
Metal Tube Variable Area Meter


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Technology Model/
Gas Flow Liquid Flow Steam Flow Line Size Temperature Pressure Viscosity Accuracy Considerations
Variable Area ALVAMT
Liquids must be clean


Variable Area Flow Meters

ALVA Family
Technology Model Line Sizes Flow Rate Viscosity Accuracy Pressures Temperature Materials Mounting Orientations Outputs

Metal Tube
ALVAMT ½"-8"
(8 - 400mm)
0.01-660 GPM
(0.05 - 2,500 LPM)
1~300 cP ±1.5% (Std), ±2.5% w/ PTFE materials 930 psig (64 barg) 575 °F (300 °C) max 304SS (Std); 316SS, PTFE, or Tantalum (Opt) Horizontal or vertical Analog 4-20 mA, 0-5 VDC, HART, swtch & open collector

Glass Tube
Not Available From SMC ¼" - 3"
(6 - 80mm)
0.05 to 264 GPM (0.005 to 1000 LPM) < 50 cP recommended ±0.50% ~ ±5.0 of reading depending on make & model <100 psig (7 barg) Up to 350 °F (180 °C) max. depending on make & model Borosilicate, acrylic, or polycarbonate tube, Stainless Steel float, depends on make & model Vertical only Switch & open collector