C Sensor Mounting Considerations; General; Signal Spread - Xylem MJK Shuttle Manual

Appendix

C Sensor mounting considerations

General

The ultrasonic sensor is characterized by a
very narrow spread of the ultrasonic signal
(3 ° - 7 ° depending on the type of sensor),
which makes it possible to use the ultrason-
ic sensor under very tight conditions, i.e. in
narrow wells or tanks. 80 % of the ultrasonic
signal is concentrated within this area, which
will give a sufficient echo that is sufficient in
the far most cases.
It is required, though, that the ultrasonic
signal is not being muffled or disturbed by
gratings, pipes, cables etc., and that the
ultrasonic sensor is not mounted so the
ultrasonic signal is sent too close to a tank
wall or well wall.

Signal spread

The illutration to the left shows the spread
of the ultrasonic sensor in conjunction with
the measuring distance, the ultrasonic signal
spread will be 57 cm at a measuring dis-
tance of 9 m. It will appear, that increasing
the measuring distance the distance from
the center line to a smooth wall should be
increased accordingly.
Distance
Spread (cm) Min. dist. from wall (cm)
(m)
3° 6° 7° at 3°
15 20 22 8
1
2 20 31 34 10
3 26 41 47 13
4 31 52 59 15
5 36 62 71 18
6 41 73 83 21
7 47 83 96 23
8 52 94 108 26
9 57 104 120 29
10 62 115 132 31
11 68 125 145 34
73 136 157 36
12
78 146 169 39
13
83 157 181 42
14
89 167 194 44
15
Table 1: The ultrasonic signal spread along a smooth
wall and minimum distance to center line in
conjunction to the measuring distance.
EN 2.10 Shuttle Manual 1712
at 6° at 7°
10 11
15 17
21 23
26 29
31 36
36 42
42 48
47 54
52 60
57 66
63 72
68 78
73 85
78 91
84 97
Figure 1: The signal spread in conjunction with the
Spread-3-6-7.xls
43
measurement distance. The spread value
should be increased by 50 - 100 % if the
surface is not smooth!
NB!
Max. measuring
distance is
31½ ft when us-
ing a standard
sensor bracket !
For greater
distances the
bracket should
be extended
further out over
the well or tank.
SW 838023