Keeping Oil Tankers on the Level

Most people don't give much thought to how petroleum products make their way from the oil field or offshore platform to their neighborhood gas pump. The people at Saab Marine Electronics sure do though. As the world leader in marine tank gauging systems, the Swedish company handles one of the most difficult parts of transporting the slippery stuff - keeping tabs on liquid levels in oil tankers.

The company's product, TankRadar G3, uses a QNX 4-based radar level-measurement system to measure ullage (the amount that a container is less than full) to a precise +/- 5mm, even if the liquid cargo is agitated or foamy. The system also accurately measures temperature, pressure, and corrects for parameters such as thermal expansion of the tank, to give a complete picture of liquid cargo during all stages of transport.

Accurate information is especially important during the loading stage where even a slight overfill could result in a dangerous situation. So, when the Saab engineers went looking for an OS for TankRadar, the needs of realtime performance, high availability, and fault tolerance were uppermost in their minds. The got all three with QNX.

The result is the QNX-based G3 workstation that tanker staff use to access two databases: one for configuration (stores static data to Dbase database files) and one dynamic process database (temporarily stores measurement data). There is one process for supervision and control of the system, and many processes for communication with external devices such as valves, pumps, radar tank gauges, temperature and pressure sensors, and so on. Users interact with the workstation with a light pen or keyboard. With Saab TankRadar, tanker staff always have access to instant, accurate, and reliable information.

Some 40,000 Saab TankRadar systems systems have been installed on both tankers and onshore tanks at refineries, tank terminals, and chemical plants worldwide. And over 50 percent of new tankers are built with a TankRadar system on board. Thanks in part to QNX, TankRadar's safety and reliability record has made the system the standard in the field of level measurement systems.