Skip To Content

Why Use a Rotameter (Variable Area Meter) to Measure Flow


 What is a rotameter? A rotameter (variable area meter) is a flow meter that measures volumetric flow of liquids and gases.  There is no difference between a rotameter and flow meter, and these terms are used interchangeably. The technique for measuring flow is accomplished by a freely moving float finding equilibrium in a tapered tube. The flow rate is then read from either a scale next to the tube or a scale on the tube. The rotameter is estimated to be in its second century of serving customers and their many and various flow flow meter applications. Rotameter applications extend across industries because it was and still is an economical way of measuring very low to high flow rates. Customers have been asked why they select rotameters. Their top six responses are clues as to why a rotameter continues to be successful even after a hundred years.

  1. No external power required – Rotameters are mechanical devices which do not require power to provide flow measurement. This allows rotameters to be installed in hazardous areas and remote areas where it would be expensive to supply power.
  2. You can see the process – Customers not only get a flow measurement reading but a look into their process. Is the process dirty or cloudy looking which could mean filters need to be changed? Is the process the correct color, are their bubbles in the liquid.
  3. Rotameters are cost effective – Both rotameter price and function contribute to savings on the job. Rotameters can be installed with other flow measurement technologies and be used to complement each other at an economical price.
  4. Simple to install and maintain – Rotameters are quickly installed by connecting the process line to the inlet and the outlet of the rotameter. Make sure the meter is vertical and you are now ready to measure flow.
  5. Low pressure drop – Most small rotameters have only a few inches of water column pressure drop. This means rotameters can be installed in many places in the process. Small pressure drops mean smaller pumps!
  6. Repeatability – Given the same process conditions a rotameter will accurately repeat the flow measurement day after day.
These six features assure rotameters will continue to be important products to measure flow now and in the future.

About The Author

Jim Dillon
Global Product Manager

Jim is the global product manager for variable area products (rotameters) at Brooks Instrument.

Subscribe to Our Newsletter Here!