VEGA VEGAPULS 56K - Manual (Page 4)

4 VEGAPULS 56K
22915-EN-041227
Product description
1 Product description
Level measurement in high temperature proc-
esses or of products with high temperatures
was formerly very difficult or even impossi-
ble. And if the measurement had to be made
under high pressure, as well, there was prac-
tically no measuring system available. Not to
mention a non-contacting system with high
measurement accuracy.
In distillation and stripper columns, levels
(e.g. of sump, plate and head products)
were usually measured indirectly up to now
via pressure transmitters or differential pres-
sure measurements. The installation required
for such pressure measuring systems (pres-
sure lines, pressure transmitters…) is con-
siderable and expensive, often amounting to
several times the value of the sensor itself.
Due to the lack of suitable alternatives, instru-
mentation departments have not only had to
live with this but also accept high mainte-
nance costs (cleaning of measuring pipes,
errors by condensation, buildup on the dia-
phragm) as well as inadequate accuracy
(temperature errors, density fluctuations,
installation faults…).
The requirements of the petrochemical indus-
try on 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, materials 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 state of affairs defines the development
goals for a high-temperature radar level
measuring system, the VEGAPULS 56 series.
The new series represents an innovation in
high temperature radar sensors for level
measurement, in temperatures up to 350°C
and pressures up to 64 bar.
The sensors would not have been possible
without the new developments in materials
science and production technology. A spe-
cially developed ceramic is used as coupling
material. It has high frequency characteristics
similar to those of plastic materials, which are
normally used. But it demonstrates incredibly
high chemical and thermal resistance.
The sensor is connected to the process only
via high-grade, expensive materials. This
refers not so much to the flange of high-alloy
stainless steel (1.4571 or better), as to the
specially developed ceramic (Al
2
O
3
) and its
connecting elements. The ceramic rod re-
ceives from the high frequency module (from
the intelligent Fuzzy-Logic processing elec-
tronics) the radar signals and its cone-
shaped end operates as emitter and
receiver. The seal between stainless steel
flange and ceramic rod is an expensively
produced 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 outputted as level.
Measuring principle:
emission – reflection – reception
Extremely small 5.8 GHz radar signals are
emitted from the antenna of the radar sensor
as short pulses. The radar pulses reflected
by the sensor environment and the product
are received by the antenna as radar ech-
oes. The running period of the radar pulses
from emission to reception is proportional to
the distance and hence to the level.