LEVEL INSTRUMENTS FOR TANK OVERFILL PROTECTION

Tank Overfill Protection: Recommended Practice for Level Control External Floating Roof Tank overfill incidents in recent years have resulted in loss of life and billions of dollars in damages to petroleum facilities worldwide. One of the worst incidents — the overflow of a gasoline storage tank at Buncefield Oil Depot (U.K.) — has been traced to the failure of level control to maintain containment of the flammable liquid. More common are minor spills that cause significant environmental impact and result in millions of dollars in clean-up fees and environmental agency fines. In the wake of this...

Tank Categories & Recommended Instrumentation API 2350 categorizes storage tanks by the extent to which personnel are in attendance during receiving operations. The overfill prevention methodology is based upon the tank catagory. ATG with High-High Alarm (Automatic Tank Gauge) Independent High-High Alarm Control Room (Automatic Tank Gauge) Control Room Category 1 Fully Attended • Personnel must always be on site during the receipt of product, must monitor the receipt continuously during the first and last hours, and must verify receipt each hour. • Personnel must be present during the initial...

Levels of Concern (LOCs) Critical High AOPS Activation High-High Maximum Working Minimum Working Levels of Concern are calculated product levels in the tank upon which all alarm and alert positions and response times are based. Careful calculation of LOCs ensures the success of the OPS. Level Required Action Critical High Level (CH) - Required Highest level before tank damage or product overflow Spill Management Emergency Response Automated Overfill Prevention System (AOPS) Activation Level - Required with AOPS Maximum level at which termination can be automatically initiated without level reaching...

Roof Types Fixed Roof or Floating Roof with Instrument Well Internal Floating Roof Recommended Equipment: • Eclipse® Guided Wave Radar Transmitter • Pulsar® Radar Transmitter • Jupiter® Magnetostrictive Transmitter (Orion Instruments®) • Echotel® Model 961/962 Ultrasonic Switch • Model A15 Displacer Switch External Floating Roof Recommended Equipment: • Pulsar® Radar Transmitter • Model A15 Displacer Switch Recommended Equipment: • Pulsar® Radar Transmitter • Model A15 Displacer Switch

Recommended Level Switches Point Level Sensors Point level sensors actuate at one or more discrete levels. These types of instruments may be used as the HH sensor and may be of a mechanical or electronic technology. Sensors used on floating roof tanks must detect the roof as well as the liquid should the roof become submerged. Additional point sensors may be used for additional alarms or alerts as determined by the operator. Single-Point Top Mount Buoyancy Displacer Switch Single-Point ECHOTEL Model 961 Contact Ultrasound Switch Dual-Point ECHOTEL Model 962 Contact Ultrasound Switch • Furnished...

Recommended Level Transmitters Continuous Level Sensors Continuous level sensors output an analog-type signal over a specified range of the tank height. Continous sensors may be used as the level sensor or as the high-high alarm sensor. Additional continous level sensors may be used to monitor additional alarm or alert points as determined by the tank operator. ECLIPSE Model 706 Guided Wave Radar Transmitter PULSAR Model RX5 Pulse Burst Radar Transmitter JUPITER Magnetostrictive Transmitter (Orion Instruments®) • Low dielectric media capability. • Non-contact technology • Continuous diagnostics...

S p e c i a l A p p l i c at i o n S e r i e s Other industry and special application brochures from MAGNETROL include: • Chemical • Crude Oil Processing • Flue Gas Desulfurization • Food & Beverage • Interface Level Measurement • Life Science • Mass Flow Measurement • Modular Skid Systems • Natural Gas Processing • Nuclear Power • Petroleum Refining • Power Generation • Pulp & Paper Mills • Renewable Energy • Steam Generation • Tank Bridle Level Measurement • Understanding Safety Integrity Level (SIL) • Water & Wastewater PLEASE NOTE: The instruments recommended in these brochures are based...