What indicates a high level alarm on a Type III operating storage tank?

When identifying a high level alarm on a Type III operating storage tank, the correct indication is that it both flashes and a vibrating horn sounds. This combination serves as an important alert system to ensure that operators are quickly made aware of potential overfill situations or other issues that may require immediate attention.

The flashing lights provide a visual indication that is easily noticeable, especially in environments where sound may not be readily audible, while the vibrating horn adds an additional layer of alert that can prompt immediate action regardless of other noises in the surroundings. This dual-alert system is crucial for maintaining safety protocols in storage tank operations, as it maximizes awareness of critical tank statuses.

On the other hand, while illuminated signals are often used in alarm systems, they are typically associated with steady alerts rather than flashing, which indicates more urgency and a clear change in normal conditions. The specific combination of a flashing light and vibrating horn creates a distinct urgency that emphasizes the need for prompt action in response to the high level alarm.