VEGA VEGAPULS 41 Profibus PA - Manual (Page 16)

16 VEGAPULS 41 – Profibus PA
27292-EN-041227
Screwed antenna on 1½“ mounting boss
2.2 Measurement of liquids
Radar sensors are usually mounted on short
DIN socket pieces. The lower side of the
instrument flange is the reference plane for
the measuring range. - The socket piece
should be as short as possible, max. 70 mm.
When mounting on dished vessel tops, the
antenna length should correspond at least to
the length of the sockets.
In vessels with dished or rounded tops,
please do not mount the instrument in the
centre or close to the vessel wall.
Dished tank tops can act as paraboloidal
reflectors. If the radar sensor is placed in the
focal point of the parabolic tank, the radar
sensor receives amplified false echoes. The
radar sensor should be mounted outside the
focal point. Parabolically amplified echoes are
thereby avoided.
Antenna directly on the vessel top
If the stability of the vessel will allow it (sensor
weight), flat mounting directly on the vessel
top is a good and cost-effective solution. The
top side of the vessel is the reference plane.
Screwed antennas, especially when used on
small vessels, are mounted in sockets. The
antenna fits into even the smallest vessel
connection openings with 1½“ socket. The
socket must not be longer than 70 mm.
Reference plane
< 70 mm
Mounting and installation
Filled vessel
In a completely filled vessel, you see addi-
tional multiple echoes at two, three or four
times the distance of the product surface
echo.