VEGA VEGAPULS 43 Profibus PA - Manual (Page 21)

VEGAPULS 43 – Profibus PA 21
ø50
> 300 mm
Tube antenna system with ball valve cutoff in measur-
ing tube
Ball valve
Vent hole
Deflector
Mounting and installation
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Openings in a surge pipe for mixing of inhomogene-
ous products
slightly inhomogeneous
liquids
inhomogeneous liquids
homogeneous
liquids
Standpipe measurement of inhomoge-
neous products
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Row of holes in one axis with the type label
Type label
If you want to measure inhomogeneous or
stratified products in a surge pipe, it must
have holes, elongated holes or slots. These
openings ensure that the liquid is mixed and
corresponds to the liquid in the vessel.
The more inhomogeneous the measured
product, the closer the openings should be
spaced.
Due to radar signal polarisation, the holes or
slots must be positioned in two rows offset
by 180°. The radar sensor must then be
mounted so that the type label of the sensor
is aligned with the rows of holes.
Every wider slot causes a false echo. The
slots should therefore not exceed a width of
10 mm in order to keep the signal noise level
to a minimum. Round slot ends are better
than rectangular ones.
Surge pipe with ball valve
If a ball valve is mounted in the surge pipe,
maintenance and servicing can be carried
out without opening the vessel (e.g. if it con-
tains liquid gas or toxic products).
A prerequisite for trouble-free operation is a
ball valve throat that corresponds to the pipe
diameter and provides a flush surface with
the pipe inner wall. The valve must not have
any rough edges or constrictions in its chan-
nel. The distance to the sensor flange should
be at least 300 mm.