SONOGAS – System for Non-Intrusive Level- and Limit
Measurement of Liquefied Gases
Application
Level control with ultrasound from the outside through the wall is used for a number of
liquefied gases. Successful applications can be found in various areas, such as the
measurement of propane/butane (LPG), propylene and other hydrocarbons, ammoniac
(NH3), refrigerants (e.g. R134a) and other technical gases such as sulfur dioxide (SO2) and
acetaldehyde (CH3CHO).
The device can be used for limit measurement (signaling via an isolated relay output) as well
as for continuous level measurement (current output : 4 … 20 mA). For level measurement
the temperature compensation is carried out in the preamplifier. The measurement system
consists of a probe, which is fixed to the tank by means of fastening material, a preamplifier
as well as a corresponding transducer (placed in the central control room). Both systems can
also be applied in combination.
Advantages
Since the SONOGAS Systems measures through the wall, even through lacquer coats,
enamellings and coatings, the installation can be carried out as a retrofitting without
interrupting ongoing operations and without emptying the tank. There is no contact between
probe and medium which leads to hardly any wear at the probe.
Principle
Our devices work according to the impulse-re ection method. The ultrasonic impulse passes
the pipe wall and spreads through the liquid
which is to be measured.
For limit measurement (probe is fixed
sideways at the pipe wall) the transducer
measures the echo, which is reflected by the
opposite pipe wall. For level measurement
(probe is mounted at the bottom of the tank)
the ultrasonic echo, which is reflected at the surface of the liquid and returning back to the
probe, are measured. If the acoustic velocity
(specific value for different liquefied gases) is
known, measuring in between sending and
receiving the signals allows to determine the
current level.
Functional Prerequisites
- Liquefied gases in a temperature range of -40 ... +80 °C
- Thermal insulation and loose layers of paint and r ust in the area where the sensor is to be mounted must be removed; varnishing and coatings may stay if suitable
- Container diameter of ca. 1 ... 25 m, wall thickness > 50 mm
- Single-shell containers, no fixtures within the measuring section
Application Example
AB Kontrol installed for a Turkish gas supplier the SONOGAS 30 system at LPG tanks
(mixture of 30% propane and 70% butane). After a longer period of testing the user was
convinced of the reliability and the high measuring accuracy at different temperatures and
operating conditions. Based on an automated content measurement the user is able to
organize his stock optimally.
References
- AB Kontrol (Turkey) – propane/butane
- Infraserv Logistics GmbH (Frankfurt Höchst) - acetaldehyde
- Total Petrochemicals France – propane/butane
- Configuration for limit measurement: SONOGAS 20
- Probe and preampli er are certi ed after ATEX and approved for Ex-Zone 1.
- Limit measurement: The analysis device SONOCONTROL 20 is mounted outside the
hazardous area.
Configuration for level measurement: SONOGAS 30
- Probe and preamplifier (incl. temperature sensor) are certi ed after ATEX and approved
for Ex-Zone 1.
- Level measurement: The analysis device SONOMETER 3 0 is mounted outside the
hazardous area.
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