Site Search Tool
Search by Part Number
 
Quick Links
  Resource Directory
  About Us
  Contact Us
  Terms & Conditions
  Privacy Policy
     
Companion Sites

Please visit our entire family of online industrial supply outlets!

MeineckeMeters.com
Mechanical Turbine Water Meters
BuyHedland.com
Hedland Variable Area Flow Meters
Divider

How do they work? ...Doppler Flow Meters
Non-Invasive Flow Measurement

Doppler flow meters measure flow from outside a pipe utilizing a strap-on sensor which continuously transmits high frequency sound (640 kHz).  Sound waves travel through the pipe wall and into the flowing liquid and are then reflected back to the sensor from solids or bubbles in the fluid. If the fluid is in motion, the echoes return at an altered frequency proportionate to flow velocity. Doppler flow meters continuously measure this frequency shift to calculate flow.

Doppler Flow Meter Animation

The Doppler effect was first documented in 1842 by Christian Doppler, an Austrian physicist. We hear everyday examples of Doppler: the sound of a train whistle changing pitch as it passes by, or the exhaust noise from a race car as it speeds past our location.

The Doppler technique only works on liquids which contain solids or gas bubbles to reflect its signal. These are "difficult" liquids that may damage regular flow meters: slurries, sludge, wastewater, abrasives, viscous and corrosive chemicals. Because the sensor mounts on the outside of the pipe, there is no pressure drop and no obstruction to flow.

For best performance Doppler sensors should be mounted away from turbulence creating devices like pipe elbows and tees, and away from velocity increasing devices like controlling valves and pumps. Typical accuracy is +2% of full scale.

Doppler instruments include a strap-on sensor, connecting cable and an electronics enclosure which can be mounted at a convenient location nearby (within 500 ft / 152 m). Sensors can be rated intrinsically safe for mounting in hazardous-rated locations.

Compliments of Greyline Mfg.

Doppler Flow Meters - Coming soon to BuyGPI.com

Your cart is empty.
 

We Accept:
 
We accept Visa, MC and AMEX

Secure Transactions by:
 

A Business Unit of...
A Business Unit of Cross Company, Established 1954

Log-In / Log-Out