Electronic differential pressure transmitters from VEGA Australia are recommended for level measurement of liquid gas stored in spherical tanks in refineries.
Typically a mixture of propane and butane, liquid gas is a by-product of petroleum refining, and is considered an ideal fuel for cars (LPG) and for heating with its high energy content.
Measuring the liquid levels in these storage tanks is a challenging task because liquid gas has physical properties that are not conducive to measurement, leaving only a few measuring methods suitable for the purpose. For safety reasons, two redundant measurement setups and a separate overfill protection system are always required. All measuring systems must also be SIL2 qualified.
Differential pressure transmitters with capillary systems are often used to measure the liquid levels in these tanks. Due to the huge dimensions of the spherical tanks, extremely long capillary tubes are required; when exposed to outdoor temperatures, these tubes influence the measured values significantly.
To measure liquid gas in a spherical storage tank measuring 21m in height and a tank pressure of 300 mbar, with medium temperature being -10°C ~ 0°C and ambient temperature being -20°C ~ +40°C, VEGA recommends electronic differential pressure measurement with VEGABAR 82 and 86 for this measurement task. In this master/slave system, the capillary tubes are replaced by an electrical connection.
In contrast to capillary systems, electronic differential pressure transmitters are not affected by the medium temperature or the ambient temperature. Even small level changes are recognised immediately, enabling the user to get accurate and reliable measurements at all times. The absence of capillaries in the process eliminates the need for mechanical protection and maintenance of these components. The sensors deliver the medium temperature and the static pressure as measured values simultaneously.
Key user benefits of VEGABAR electronic differential pressure transmitters include high operational reliability through reliable, accurate readings; cost-effective instrumentation without capillaries and protective covers; and output of medium temperature and static pressure with fewer tank fittings, simpler installation, and elimination of superfluous measuring points.