VEGA VEGAPULS 56V - Manual (Page 4)

4 VEGAPULS 56V
Product description
1 Product description
Level measurement on high temperature
processes or on mediums with high tempera-
ture was formerly very difficult or even im-
possible. If in addition the measurement
should be made under high pressure, up to
now there was no measuring system avail-
able. 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 prod-
ucts) could generally only be measured by
pressure sensors or differential pressure
measurements. The installation required for
such pressure measuring systems (pressure
lines, pressure transmitters…) is consider-
able and expensive, often amounting to sev-
eral times the value of the sensor itself. Due
to missing of suitable alternatives, instrumen-
tation 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 dia-
phragm…) and often had to accept inad-
equate accuracy (temperature errors, den-
sity 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
measuring system of VEGAPULS 56 series.
A special new development of high-tempera-
ture 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
stainless 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 the radar signals and
the cone-shaped end works as emitter and
receiver. The seal between stainless steel
flange and ceramic rod is made with a Tanta-
lum 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.