Dynasonics Fusion Water Flow Meter - Manual (Page 6)

6
OPERATING THEORY
The FUSION ultrasonic flow meter is designed to measure
volumetric flow of clean, solids-bearing or aerated liquid on full
pipes. There are no moving parts to jam or wear and the product
cannot be damaged by gas pockets, particulate or high flowing
conditions. The unit contains several input/output options for
integration with monitoring and control systems.
The flow meter’s patent pending operation consists of
continuously measuring flow using both transit time and Doppler
ultrasonic sound techniques, and using the better of the two
signals to calculate the flow rate.
When in transit time mode, the flow meter transmits an
ultrasonic sound from the upstream transducer into the flowing
liquid. The travel time to the downstream transducer is
measured. The flow meter then transmits an ultrasonic sound
from the downstream transducer into the flowing liquid. The
travel time to the upstream transducer is measured. The
difference between the two travel times is then used to calculate
the measured flow rate.
When in Doppler mode, the flow meter transmits an ultrasonic
sound from its transmitting transducer into the flowing liquid.
The sound will be reflected by sonic reflectors (gas bubbles or
particulate) suspended within the liquid and recorded by the
receiving transducer. If the sonic reflectors are moving within the
sound transmission path, sound waves will be reflected at a
frequency shifted (Doppler frequency) from the transmitted
frequency. The shift in frequency will be directly related to the
speed of the moving particle or bubble. This shift in frequency is
interpreted by the instrument and converted to various user
defined measuring units.
FUSION retains all user configured data and accumulated flows
(totalizers) in non-volatile Flash memory indefinitely.