VEGA VEGASON 51P…53P Profibus PA - Manual (Page 23)

VEGASON 51P … 53P 23
Mounting and installation
4 Mounting and installation
4.1 General installation instructions
Measuring range
Beside other criteria, you select your instru-
ment according to the required measuring
range. The reference planes for the min. and
max. distance to the liquid or solid is the
transducer end or for instruments in flange
version, the instrument flange. Please note
the information on the reference plane in
chapter "3.3 Dimensions“. The max. filling
depends on the required min. distance of the
instrument used (0.25 m up to 0.75 m) and
the mounting location of the instrument or the
transducer.
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Min. distance, max. measuring range and span (example VEGASON 51, 52 and 53)
Max. meas. distance: 4 m (type 51), 7 m (type 52), 15 m (type 53)
Full
Span
Min.
distance
1m
Empty
Min.
distance
Min.
distance
0.25 m 0.4 m 0.75 m
Reference plane
Type 51 Type 53 Type 52
max. meas. range
Beam angle and false echoes
The ultrasonic impulses are focused by the
transducers. The impulses leave the trans-
ducer in conical form similar to the beam
pattern of a spotlight. The beam angle is 5.5°
(VEGASON 51/5) or 3° (VEGASON 53) at
-3 dB emitted power.
Any object, e.g. tubes or struts inside this
emission cone will cause a large false echo.
Especially within the first few meters of the
emission cone, pipes, struts, or other installa-
tions can interfere with the measurement. At a
distance of 6 m, the false echo of a strut has
an amplitude nine times greater than at a
distance of 18 m.
At greater distances, the energy of the ultra-
sonic impulses distributes over a large area,
thus causing weaker echoes from obstruct-
ing surfaces. The interfering signals are
therefore less critical than those at close
range.
If possible, orient the sensor axis perpen-
dicularly to the product surface and avoid
vessel installations (e.g. pipes and struts)
within the 100 % area of the emission cone.
The following illustration of the ultrasonic
beams is simplified and represents only the
main beam - a number of additional weaker
beams exists.