Dynasonics TFX Ultra Transit Time Flow Meters - Manual (Page 26)

4. The two marks on the pipe are now properly aligned and measured. If access to the bottom of the pipe prohibits the
wrapping of the paper around the circumference, cut a piece of paper 1/2 the circumference of the pipe and lay it over the
top of the pipe. The length of 1/2 the circumference can be found by:
½ Circumference = Pipe O.D. × 1.57
The transducer spacing is the same as found in the Transducer Positioning section. Mark opposite corners of the paper on the
pipe. Apply transducers to these two marks.
LESS THAN ¼” (6 mm)
Figure 19: Paper template alignment
Line Marking
Circumference
Edge of
Paper
Fold
Pipe Circumference
Crease
(Center of Pipe)
Transducer
Spacing
Figure 20: Bisecting the pipe circumference
5. For DTTN, DTTL, and DTTH transducers, place a single
bead of couplant, approximately 1/2 inch (12 mm) thick,
on the flat face of the transducer. See Figure 12 . Generally,
a silicone-based grease is used as an acoustic couplant,
but any good quality grease-like substance that is rated
to not flow at the temperature that the pipe may operate
at will be acceptable.
6. Place the upstream transducer in position and secure
with a stainless steel strap or other fastening device.
Straps should be placed in the arched groove on the end
of the transducer. A screw is provided to help hold the
transducer onto the strap. Verify that the transducer is
true to the pipe, adjust as necessary. Tighten transducer
strap securely. Larger pipes may require more than one
strap to reach the circumference of the pipe.
7. Place the downstream transducer on the pipe at the
calculated transducer spacing. See Figure 21 . Using firm
hand pressure, slowly move the transducer both towards
and away from the upstream transducer while observing
signal strength. Clamp the transducer at the position
where the highest signal strength is observed. Signal
strength of between 5…98 is acceptable.
The factory default signal strength setting is 5, however
there are many application specific conditions that may
prevent the signal strength from attaining this level
TOP VIEW
OF PIPE
Figure 21: Z-Mount transducer placement
V-MOUNT AND W-MOUNT INSTALLATION
Page 26 March 2014