4
VEGAPULS 56K
Product description
1 Product description
Level measurement on high temperature
processes or on mediums with high tempera-
tures was formerly very difficult or even impos-
sible. If in addition the measurement should be
made under high pressure, up to now there
was no measuring system available. Apart
from a non-contact measurement with good
measuring accuracy.
In distillation and stripper columns, up to now
levels (e.g. of sump, plate and head products)
could generally only be measured by pressure
sensors or differential pressure measurements.
The installation required for such pressure
measuring system (pressure lines, pressure
transmitters …) is considerable and expensive
often amounting to several times the value of
the sensor itself. Due to missing of suitable
alternatives, instrumentation departments have
not only to arrange with this fact but also with
high maintenance costs (cleaning of
measuring pipes, errors by condensation,
build-up on the diaphragm…) and often had to
accept inadequate accuracy (temperature
errors, density fluctuations, installation faults
…).
The requirements of the petrochemical indus-
try for a non-contact level sensor are the
following:
• independent of temperature and pressure
• process temperature up to 350
°
C
• process pressure up to 64␣ bar
• high-resistance wetted parts for universal
use
• accuracy 0,1␣ %
• rugged metal housing
• Ex-approved (available in EEx d and EEx␣ ia)
• Loop-powered as well as digitally connect-
able
This initial position defines the development
aims for a high-temperature radar level meas-
uring system of VEGAPULS 56 series. A
special new development of high-temperature
radar sensors for level measurement in
temperatures up to 350
°
C and pressures up to
64␣ bar.
Sensors which would not have been possible
without the new results in the material and
production technology. An especially devel-
oped ceramics is used as coupling material.
This ceramic is chemically and thermically
very high resistant.
The sensor materials in contact with the proc-
ess are all highly resistant. This refers not so
much to the flange material of high-alloy stain-
less steel (1.4571 or superior), as to the
specially developed ceramic (Al
2
O
3
) and its
gland. The ceramic rod receives from the high
frequency module (from the intelligent Fuzzy-
Logic-processing electronics) the radar
signals and the cone-shaped end works as
emitter and receiver. The seal bet-ween
stainless steel flange and ceramic rod is made
with a Tantalum seal ring.
1.1 Function
Ra
dio
d
etecting
a
nd
r
anging: Radar.
VEGAPULS radar sensors are used for non-
contact and continuous distance measure-
ment. The measured distance corresponds to
a filling height and is provided as level.
Measuring principle:
emission – reflection – receipt
Smallest 5,8␣ GHz radar signals are emitted
from the antenna of the radar sensor as short
pulses. The radar impulses reflected by the
sensor environment and the product are
received by the antenna as radar echoes. The
running period of the radar impulses from
emission to receipt is proportional to the
distance and hence to the level.
The radar impulses are emitted by the antenna
