TDS-100H Handhold Ultrasonic Flowmeter Ver.8.08 - 2 -
* Work properly near transverters
* 0.5 second totalizing period
* 100 Pico-second resolution of time measurement
§1.3 Principle of Measurement
The TDS-100 ultrasonic flow meter is designed to measure the fluid velocity of liquid within a
closed conduit. The transducers are a non-contacting, clamp-on type, which will provide benefits
of non-fouling operation and easy installation.
The TDS-100 transit time flow meter utilizes two transducers that function as both ultrasonic
transmitters and receivers. The transducers are clamped on the outside of a closed pipe at a specific
distance from each other. The transducers can be mounted in V-method where the sound
transverses the pipe twice, or W-method where the sound transverses the pipe four times, or in
Z-method where the transducers are mounted on opposite sides of the pipe and the sound crosses
the pipe once. This selection of the mounting method depends on pipe and liquid characteristics.
The flow meter operates by alternately transmitting and receiving a frequency modulated burst of
sound energy between the two transducers and measuring the transit time that it takes for sound to
travel between the two transducers. The difference in the transit time measured is directly and
exactly related to the velocity of the liquid in the pipe, as shown in Figure 1.
Where
θ
is the include angle to the flow direction
M
is the travel times of the ultrasonic
beam
D
is the pipe diameter
Tup
is the time for the beam from upstream transducer to the downstream one
Tdown
is the time for the beam from downstream transducer to the upstream
one
Δ
T=
Tup –Tdown
§1.4 Parts Identification
Converter:
Down stream transducer
spacing
flow
Upstream transducer
Tdown
Tup
θ
down
up
T
T
T
MD
V
•
Δ
×
=
θ
2
sin
