Friday, May 29, 2015

Introduction to Rotameters

(courtesy of
King Instrument)
A rotameter is one particular type of variable area flowmeter that measures flow by varying the cross-sectional area a fluid or gas travels through in a closed tube.

  • Requires no external power.
  • Is a simple device that can be easily manufactured out of inexpensive materials.
  • Linear scale.
  • The clear glass tube is resistant to thermal shock and chemical reaction.
  • Must be mounted vertically, with designated top and bottom, and with the fluid flowing from bottom to top.
  • Graduations on a given rotameter are only accurate for a given substance at a given temperature. Separate rotameters must be used for fluids with different densities and viscosities, or multiple scales on the same rotameter must be used.
  • Resolution is relatively poor and gets worse near the bottom of the scale.
  • Oscillations of the float and parallax lend to reduced accuracy.
  • Difficult to automate - primarily a manual / visual device

For more information on rotameters, contact:

M.S. Jacobs and Associates, Inc.
810 Noblestown Road
Pittsburgh, Pa 15205
Toll free: 800 348 0089
Fax: 412-279-4810