Dynasonics TFXP Series Transit Time Ultrasonic Flow Meter - Manual (Page 9)

Rev. 5/09 -1.7- TFXP
PART 1 - INTRODUCTION
The TFXP ultrasonic flow meter is designed to measure the fluid
velocity of liquid within closed conduit. The transducers are a non-
contacting, clamp-on or clamp-around type, which will provide
benefits of non-fouling operation and ease of installation.
TFXP transit time flow meters
utilize two transducers that function
as both ultrasonic transmitters and
receivers. See Figure 1.4. DTTN
and DTTH transducers are
clamped on the outside of a closed
pipe at a specific distance from
each other. The transducers can be
mounted in V-Mount where the
sound transverses the pipe two
times, W-Mount where the sound
transverses the pipe four times,
or in Z-Mount where the transducers are mounted on opposite sides
of the pipe and the sound crosses the pipe once. This selection is
based on pipe and liquid characteristics.
DTTS and DTTC (small pipe transducers) have both transmit and
receive crystals imbedded in a single clamp-around transducer so
no measurement between transducers is required.
The flow meter operates by alternately transmitting and receiving a
frequency modulated burst of sound energy between the two
transducers and measuring the time interval that it takes for sound
to travel between the two transducers. The difference in the time
interval measured is directly related to the velocity of the liquid in the
pipe.
The TFXP flow meter can be successfully applied on a wide range
of metering applications. The simple-to-program transmitter allows
the standard product to be used on pipe sizes ranging from 1/2 inch
(12 mm) and larger. (Transducer sets from 1/2 to 1-1/2 inch require
2 MHz transmitters and dedicated pipe transducers.) A variety of
liquid applications can be accommodated:
Because the transducers are non-contacting and have no moving
parts, the flow meter is not affected by system pressure, fouling or
wear. The DTTN transducer set is rated to a pipe surface
General
Application
Versatility
ultrapure liquids sewage cooling water
potable water reclaimed water river water
chemicals plant effluent others
Figure 1.4 —
Ultrasonic Transmission
Through a Field