Am Instru Q-FP 201, Руководство пользователя, Страница: 5 / 32

Tdown
up
flow
-2-- Q-FP 201 Handheld Ultrasonic Flowmeter
* Small and light * RS-232 serial interface
§1.3 Principle of Measurement
The Q-FP 201 ultrasonic flowmeter 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 Q-FP 201 transit time flowmeter 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, show as follows:
Downstream transducer
V = MD
x
AT
sin
20 T
v
• T
down
spacing
Where
0 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
AT=Tup —Tdown
§1.4 Packing List (Standard Configuration)
I
Upstream
transducer
Check up the packing list carefully before installing
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