May 19, 2009 - VEGA supplied IEC 61508 SIL 2, ATEX Ex approved VEGAPULS radar level transmitters to BP Oil for one of their latest tank farm upgrade projects. The 4-20mA/HART loop powered devices have narrow focusing to avoid any obstructions, thanks to their high frequency, special encapsulated antenna. The compact, lightweight design of the units, even with an Ex ‘d’ ‘ia’ two chamber enclosure, makes them ideal for mounting on a long arm over the vessel, to ensure they read clearly the correct part of the floating roof. The arm can also be fitted with a swivel mounting plate for periodic proof testing of the high level function. The signals are being used for high-high level protection as well as for ‘cross-correlation’ of the main tank gauging system readings.
This offers the potential of a higher level of security and performance than a point high level switch. For other applications it is also possible to use multiple radar units for checking that a floating roof maintains a perfectly horizontal plane, for example, on a gas-holder. The 2-wire 4-20mA HART VEGAPULS radar units have ranges up to 70m and mainly used for direct level measurement of liquids and solids in tanks and silos.
