Dynasonics TFXP Series Transit Time Ultrasonic Flow Meter - Manual (Page 22)

Rev. 5/09
- 2.4 - TFXP
TFX transit time flow meters are sold with four different transducer
types: DTTN, DTTH, DTTS and DTTC. Meters that utilize DTTN or
DTTH transducer sets consist of two separate sensors that function
as both ultrasonic transmitters and receivers. DTTS and DTTC
transducers integrate both the transmitter and receiver into one
assembly that fixes the separation of the piezoelectric crystals.
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:
• W-Mount where the sound transverses the pipe four times.
This mounting method produces the best relative travel time
values but the weakest signal strength.
• V-Mount where the sound transverses the pipe twice.
V-Mount is a compromise between travel time and signal
strength.
• Z-Mount where the transducers are mounted on opposite
sides of the pipe and the sound crosses the pipe once.
Z-Mount will yield the best signal strength but the smallest
relative travel time.
For further details, reference Figure 2.1 located under Table 2.2 on
page 2.5. The appropriate mounting configuration is based on pipe
and liquid characteristics. Selection of the proper transducer
mounting method is not entirely predictable and many times is an
iterative process. Table 2.2 contains recommended mounting
configurations for common applications. These recommended
configurations may need to be modified for specific applications if
such things as aeration, suspended solids or poor piping conditions
are present. Use of the TFX diagnostics in determining the optimum
transducer mounting is covered later in this section.
2. Transducer Spacing
PART 2 - TRANSDUCER & RTD INSTALLATION