EM6100 Handheld Portable Ultrasonic Flowmeter Ver.8.08
Flomotion
Systems,
Inc.
EM6100
7
§1.3 Principle of Measurement
The EM6100 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 EM6100 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
