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What Is Automatic Tank Gauging (ATG)? | Process Engineering Glossary
What Is Automatic Tank Gauging (ATG)?
Automatic tank gauging, commonly abbreviated ATG, is a system using automated instrumentation, such as radar, servo-driven float, or magnetostrictive level gauges, to continuously measure and report a storage tank’s liquid level, and often temperature and product identification as well, without requiring manual gauging by an operator. ATG systems typically communicate measurements to a central monitoring system, supporting both routine inventory management and, when appropriately designed, safety-related overfill prevention functions.
While ATG dramatically reduces the manual effort involved in tracking tank inventory compared to manual gauging methods, standards like API 2350 draw an important distinction between ATG used for inventory management and the independent level measurement required specifically for overfill protection purposes.
Applications of Automatic Tank Gauging
Inventory Management
ATG systems provide continuous, real-time visibility into tank inventory levels across an entire tank farm, supporting logistics planning and reducing reliance on periodic manual gauging rounds.
Overfill Protection Systems
ATG level measurements can support overfill protection functions, though this requires careful attention to the independence requirements defined in relevant standards to ensure the gauging system genuinely provides the intended safety function.
Custody Transfer Measurement
Accurate automatic tank gauging supports custody transfer measurement when product changes ownership, providing a documented, auditable record of tank contents at the time of transfer.
Benefits of Knowing Automatic Tank Gauging
Reduces manual gauging labor and error. Automated, continuous measurement eliminates much of the labor and potential error associated with periodic manual tank gauging.
Provides real-time inventory visibility. Continuous ATG data supports more responsive inventory management and logistics planning than periodic manual measurements allow.
Can support layered safety functions when properly designed. ATG systems, when designed with appropriate independence, can contribute to a facility’s overall overfill protection strategy alongside dedicated safety instrumentation.
Limitations to Consider
Not automatically suitable for safety functions. An ATG system used for routine inventory management doesn’t automatically satisfy the independence requirements needed for a genuine overfill protection safety function without deliberate design attention.
Requires calibration and maintenance. Like any instrumentation, ATG systems require periodic calibration and maintenance to maintain measurement accuracy over time.
Technology selection depends on service conditions. Different ATG technologies suit different tank types, products, and operating conditions, making technology selection an important, service-specific decision rather than a one-size-fits-all choice.
Automatic Tank Gauging FAQ
How does automatic tank gauging relate to overfill protection requirements?
While ATG can support overfill protection, standards like API 2350 require genuine independence between routine inventory gauging and the dedicated measurement used for a safety-critical high-high level trip.
Why does automatic tank gauging matter for both high and low level protection?
ATG systems commonly support both high-high level trip and low-low level trip functions, giving operators visibility across the full range of a tank’s safe operating level.
How does automatic tank gauging fit into broader process control?
ATG measurements typically feed into a facility’s process control system, supporting closed-loop control of filling operations alongside standard storage tank and atmospheric vessel management.
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