Variable Area Flow Meter Compatibility Based on Industrial Process Medium

Variable area flow meters are selected based on the compatibility between the process medium and the flow meter’s construction materials, since factors such as corrosion, temperature, pressure, and fluid cleanliness directly affect measurement performance and lifespan.

• Direct measurement of water, nitrogen, gases, chemicals
• Easy installation and low maintenance
• Compact meter, cost effective solution
• Versatile, reliable and durable
• High measurement repeatability
• Linear scale for readability
• No external power supply needed

Working Principle

Variable area flow meter measure flow using a float that is able to move freely up and down within the flow tube. The buoyancy force acting on the float, the flow resistance, and the weight of the float itself are all in equilibrium. This position of equilibrium provides the flow rate by referencing the top of the float against the scale printed on the flow tube. Guide rods are sometimes used to help stabilize the float and are more common in gas rotameters or large flow body liquid flow meters.

The float buoyancy is dependent on the density and mass of the float as well as the materials of construction and volume. The float must have a higher density than the media or it will move up in the flow tube even when there is no flow present, resulting in a measurement error. Essentially, the float must not actually float on the top of the media.