39
4.4.3 Z Method
The signal transmitted in a Z method installation has less attenuation than a signal transmitted with the
V method. This is because the Z method utilizes a directly transmitted (rather than reflected) signal which
transverses the liquid only once. The Z method (Figure 4.4-C, below) is used primarily in applications
where the V method cannot work due to signal attenuation from excessive air or solids in the liquid, thick
scale, poorly bonded linings, or very large pipes. In addition, the Z method generally works better on larger
diameter pipes where less pipe length is required for mounting.
Ensure Z is the selected mounting method.
F
IGURE
4.4-C: Z M
OUNT
1.
Establish a reference at both the 3 o’clock and 9 o’clock positions on the pipe
(Figure 4.4-D, page 40)
.
2.
Place a transducer at the 3 o’clock position.
3.
Trace the shape of the 3 o’clock transducer along its inside edge (opposite the cable connection).
Draw a horizontal line at its center. Remove the transducer
(Figure 4.4-E, page 40)
.
4.
Obtain a continuous sheet of paper longer than the circumference of the pipe. Calculator paper tape or
thermal printer paper works well for this.
5.
Fold one end of the paper across the pipe’s width to produce a clean, straight edge.
6.
Line the fold of the paper up with the horizontal centerline of the 3 o’clock transducer
(Figure 4.4-F,
page 40)
.
7.
Wrap the paper firmly around the pipe, and mark the intersection point where the fold comes in
contact with the rest of the paper
(Figure 4.4-G, page 40)
.
8.
Remove the paper from the pipe. Place the fold and intersection mark together again, and fold the
paper exactly in half
(Figure 4.4-H, page 40)
.
9.
Mark along the new fold
(Figure 4.4-I, page 40)
.
