Modernizing Tank Gauging Systems in Manageable Steps

Emerson's Lena Hansson


Bulk liquids storage tanks are used across the supply chain from upstream production through downstream petrochemicals and chemicals. A Tank Storage magazine article, Emulation: The Cost-Effective Solution to Tank Gauging Upgrades, highlights a statistic of an estimated one million bulk liquids storage tanks in use across the globe.

Many of these storage tanks use older, mechanical level measurement devices and tank gauging systems. The cost to fully modernize in terms of planning, engineering, purchasing, and associated downtime is a significant barrier. In the article, Emerson’s Lena Hansson explains:

…tank gauging emulation provides a solution that enables them [terminal operators] to easily, efficiently and incrementally replace outdated or unreliable field or control room equipment.

Tank Storage: Emulation--The Cost-Effective Solution to Tank Gauging UpgradesThere are many issues with relying on dated tank gauging systems. Many are:

…still relying on ageing tank gauging systems – incorporating mechanical devices using float or servo technology – to support overfill prevention and inventory management. This technology is susceptible to failure, and can result in unreliable measurements and high maintenance costs.

These failures can lead to:

…safety incidents, fines, substantial clean-up costs, and significant damage to a company’s reputation. Measurement inaccuracy can also lead to underutilisation of tanks and transfer uncertainty, making tank operations less efficient and thus affecting profitability.

Lena highlights the barriers with a total replacement project which includes replacing the mechanical equipment with radar level gauges and control room equipment. These tank gauging systems are often also integrated with:

…existing higher-level computer systems. In many applications, data from the tank gauging system is also transferred to accounting systems, inventory/loss control systems, distributed control systems (DCS), etc.

Gauge emulation provides a step-wise modernization path where the tank gauging system is left intact while the old float or servo technology can be replaced over time with modern radar level gauges such as the Rosemount 5900. This emulation:

…makes it possible for modern gauges to ‘talk the language’ of older devices. Consequently, a system’s existing gauges can be replaced with modern devices from other vendors without changes having to be made to the communication or wiring infrastructure.

Lena notes that the emulating gauges must be electrically compatible with the existing gauging system. Also, the measurement data sent to the existing gauging system needs to be supported. The Rosemount 5900 Series:

…can emulate a broad range of legacy gauges and proprietary fieldbus protocols. An additional benefit of this level gauge is that it can be installed within an existing tank opening, thereby making it relatively quick and easy to replace old devices.

Another level of step-wise, at your pace modernization is master emulation where the old control room equipment can be replaced with a Rosemount 2460 System Hub, which:

…collects data from legacy field devices and forwards it to a tank management system, thereby providing the operator with a real-time overview.

Read the article for more on this incremental approach in making these bulk liquids storage tanks operate more safely, reliably and efficiently, as well as a case study of the return on investment for a Texas refinery.

You can connect and interact with other tank gauging experts in the Tank Gauging group in the Emerson Exchange 365 community.