AUF610 Series Operation Manual
OP610.1.1.5R1ENG
5
1.3 Principle of Measurement
The AUF610 ultrasonic flow meter is designed to measure the fluid velocity of clean homogeneous liquids
in a closed conduit. The transducers are the ‘outside the pipe’, non-contacting, clamp-on type. This
ensures non-fouling operation and a simple, easy installation.
The AUF610 transit time flow meter utilizes two ultra-sonic transducers. Each one is both a transmitter and
a receiver. The transducers are clamped on the outside of a closed pipe in a pre-determined distance from
each other. The pipe size, pipe material and process (liquid) characteristics dictate where and how far
apart the transducers are mounted. If sound crosses the pipe once it is called the Z-method. If the sound
transverses the pipe twice it is called the V-method. If the sound transverses the pipe four times then it is
known as the W-method. The flow meter operates by alternately transmitting and receiving frequency
modulated bursts of sound energy between the two transducers. Once upstream and once downstream
and then accurately determining the time difference between the two sonic beams and the time difference
is a linear, accurate and repeatable measurement of the process velocity within the pipe. Calculating the
pipe’s internal area and integrating the velocity measurement over time results in the flow rate.
(see.Figure)
v =
M D
*
SIN 2
△
T
× Tup Tdown
*
0
Figure
NOTES:
Ө
= the angle to the flow direction
M = the transit time of the ultrasonic beam
D = the pipe diameter
Tup = the downstream transit time
Tdown = the upstream transit time
△
T = Tup -Tdown
Up stream transducer
Tup
Tdown
Down stream transducer
Spacing
