What are the benefits of using Ultrasonics for flow measurement?
Aug 13, 2014
There are many ways to measure the flow of liquids and gases. One of the newer technologies is ultrasonics, which is becoming more widespread in flow meters. What benefits have encouraged the uptake in ultrasonics?
There are two different principles for ultrasonic flow measurement;
- Doppler Effect. This uses ultrasonic waves reflected from acoustical impedance mismatches- such as solid particles or bubbles-to measure the fluid velocity. By measuring the frequency shift between the ultrasonic source andthe receiver, the relative velocity is measured.
- Time of Flight. The time for ultrasound pulses to travel between a transmitter and receiver is measured, both with and against the flow. Comparing the two values allows both the flow velocity and the speed of sound in the fluid to be measured.
Unlike the Doppler effect, this method is not dependant on particles in the fluid and is therefore more accurate making it suitable over a wider range of applications.
So what are the benefits of using Time of Flight Ultrasonic flow sensors?
- High linear accuracy (typically about 1% of flow rate) with a wide measuring range.
- With a digital signal the high accuracy is maintained by eliminaing Drift.
- It has a bi-directional flow measurement capability.
- With no moving parts to wear or fail, ultrasonics offers zero or low maintenance inputs.
- The elimination of moving parts provides long-term reliability and stability with no start-up inertia.
- Ultrasonics time of flight flow measurement can detect zero flow.
- The sensors can tolerate and are largely unaffected by extreme temperatures, fluid viscosities and densities whilst providing high corrosion resistance.
- Through the use of advanced software, ultrasonics offers self-diagnosis of its functionlity and can provide datalogging, sonic temperature measurement, flow direction and some properties such as attenuation.
- Time of flight meters can measure gases at both low and high pressures.
- With little or no intrusion into the flow path- the sensors can even be clamped to the outside of the pipe – pressure drop is minimised or eliminated.
Time of flight ultrasonic measurement technology is one of the priniple core skills of Gill R&D, which positions us to provide broad experience and insight in the development of commercially innovative and successful products utilising this leading technology solution.