VEGA VEGAPULS 45 4 … 20 mA; HART compact sensor - Manual (Page 25)

VEGAPULS 42, 44 and 45 – 4 … 20 mA 25
Sensor too close to the vessel wall
If the radar sensor is mounted too close to
the vessel wall, strong false echoes can be
caused. Buildup, rivets, screws or weld joints
superimpose their echoes onto the product
i.e. useful echo. Please ensure a sufficient
distance from the sensor to the vessel wall.
If there are good reflection conditions (liquid
medium, no vessel installations), we recom-
mend locating the sensor where there is no
vessel wall within the inner emission cone. For
products in less favourable reflection envi-
ronments, it is a good idea to also keep the
outer emission cone free of interfering instal-
lations. Note chapter "3.1 General installation
instructions“.
Wrong orientation to the product
Weak measuring signals are generated if the
sensor is not directly pointed at the product
surface. Orient the sensor axis perpendicu-
larly to the product surface to achieve opti-
mum measuring results.
Direct sensor vertically to the product surface
Correct Incorrect
Ladder
Ladder
Mounting and installation
Unfavourable
Mounting on a vessel with parabolic tank top
Correct
~ ½
vessel
radius
Unfavourable
Parabolic effects on dished or arched
vessel tops
Round or parabolic tank tops act on the radar
signals like a parabolic mirror. If the radar
sensor is placed at the focal point of such a
parabolic tank top, the sensor receives am-
plified false echoes. The optimum mounting
location is generally in the range of half the
vessel radius from the centre.