There is a common misconception that the level measurement instrumentation used in the automatic tank gauge system and overfill prevention system (OPS) on bulk liquid storage tanks must be based on different technologies.
This paper explains that technology diversification is not a requirement of the relevant industry safety standards, and that there are certain advantages to selecting the same technology for both systems. It describes why radar has become the dominant technology in such applications, with new installations often including two radar level gauges to provide both level and independent overfill prevention measurements. The paper also describes how the latest “2-in-1” technology enables a single radar gauge to be used for both level measurement and overfill prevention purposes, in compliance with industry standards, and how this allows for cost-efficient safety upgrades on existing tanks.
The owners and managers of bulk liquid storage facilities depend on accurate and reliable level measurement instrumentation within both their automatic tank gauge and their OPS. With tanks often storing materials that are hazardous, flammable, or explosive, an overfill can lead to injuries or even deaths, significant damage to assets, and extensive environmental harm. A company’s reputation can be seriously affected, while the cost of such incidents can sometimes be measured in billions of dollars.
It is therefore essential for companies storing hazardous materials to invest in a robust OPS that is compliant with current industry safety standards. IEC 61511 sets out best safety practices for implementing a modern OPS in the process industry. In addition, API 2350 addresses the minimum requirements to comply with modern best practices in the specific application of non-pressurized above-ground large petroleum storage tanks.
OPS can be either manual or automatic. Manual systems are regarded as being easier to implement and less complex, with lower initial costs. They typically consist of a level sensor or switch that transmits an audio-visual alarm to an operator, notifying them to take appropriate action, such as manually opening or shutting off a valve to prevent an overfill. However, the risk reduction factor of manual systems is limited and there is a strong trend towards replacing them with automatic systems, which can achieve higher risk reduction factors, shorter response times, and a reduced workload for operators. In bulk liquid storage tanks, automatic OPS typically consist of a level sensor, a logic solver, and a final control element in the form of actuated valve technology.
This article comes from fluidhandling edit released