36
..... Spacing & mounting the transducers
6.
Install the portable transducers:
a.
Position the slides according to the calculated spacing. The top rail of the rack is marked in inches
and the bottom rail is marked in millimeters.
b.
Apply sonic coupling compound to a transducer face, and with the cable connector end of the
transducer towards the outside of the rack, install the transducer beneath one of the slides. The
inside face of the transducer should align with the inside edge of the slide.
c.
Tighten the knobs on the slide evenly to hold the transducer in place.
d.
Repeat this procedure with remaining transducer.
7.
Ensure the transducer face is aligned normal to the pipe (Figure 4.3-A, below). The transducer face
alignment is particularly critical on small pipes due to pipe curvature. Notice that the properly installed
transducer contacts the pipe at the pipe’s centerline and that the gaps on either side of the centerline
are equal. The notches on both ends of the portable transducer rack allow the assembly to self-align to
the curvature of the pipe. Check the contacts of the notches to the pipe, and adjust as necessary.
F
IGURE
4.3-A
8.
Connect the transducer cables to the flowmeter.
The transducers should be mounted on the pipe in relation to the direction of
flow, as shown in Figure 4.3-B (below). Reversing the position of the upstream
and downstream transducers or reversing the transducer cable connections to
the instrument results in negative flow readings.
F
IGURE
4.3-B
