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  • tylerjensen38

Petroleum Tank Critical Levels, and Levels of Concern Settings, For Safety and Compliance

First you identify the critical levels and maximum flow rates and response times. Response times can vary depending on a variety of factors.

  • For a manned facility, does the operator need to go out to the tank to shut off or divert flow - or can it be done electronically with a motor operated valve?

  • For an unmanned facility, the Distance of Travel to be able to shut down or divert flow can be miles away, and weather can be a factor.

What is a Critical High level?

  • Overflow of Product

  • Exceedance of the allowable tank shell design stresses

  • Leakage from a corroded area or temporary repair

  • Level designated by the owner/operator, Considering

  • Mechanical contact of the floating roof, floating roof seals, foam chamber deflectors or foam dams, or other appurtenances with the tank roof or platform ladder structure

  • Seals rise to a level where they are in contact with vents or top of the tank shell

What are the other Levels of Concern?

  • AOPS (Automatic Overfill Prevention System) activation level

  • High-High (HH) level

  • High (H) Level 

  • Maximum Working (MW) level

What devices are used and what are the actions required?

  • The action of High-High level being reached is that an alarm will sound. The action of the AOPS is to automatically shut down or divert the flow of product without human intervention.

  • The High Level and Max Working Level actions may only be a software alarm or alert.

By understanding the different types of petroleum tank alarms and setting them appropriately, you can safely optimize your working capacity, and reduce the risk of an environmental event. 

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