A key point of the updated API 2350 recommended practices includes a provision for proof testing the equipment involved in an overfill prevention system (OPS). The new guidelines prescribe that all OPS equipment required to terminate receipt must be tested annually, while the High-High sensor alarm must be tested semi-annually. Additionally, continuous level sensors should be tested quarterly and point level sensors, semi-annually.
Information about testing of hand gauges and continuous level sensors can be found in the API’s Manual of Petroleum Measurement Standards (MPMS), Chapters 3.1A.9 and 3.1B.5, respectively.
The method of test actuation may be chosen by the tank storage operator and may include: moving the tank level, actuating a manual proofer device, initiating a web probe test, or utilizing self-diagnostics or a push-button self-test, if the instrument is so equipped.
Testing should simulate an actual High-High liquid level situation as closely as possible; however, the test doesn’t have to require filling the tank above its Maximum Working level.
Alarms and level sensors equipped with manual checks and self-diagnostics enable proof testing and aid in the evaluation of the health of an automated overfill prevention system (AOPS).