The present invention includes pressure event indicators that identify specific pressurized vessels or pipes from which a pressurized fluid has been exhausted, closed pressurized systems that implement such pressure event indicators, and methods of using such pressure event indicators. Embodiments of such pressure event indicators may include a housing having a substantially horizontal elongate passage, a rotatable axle orthogonally passing through the passage, a paddle fixedly attached to the axle having a closed position, an open position, and a shape that is complementary to a portion of the passage and that occludes a portion of the passage when the paddle is in the closed position, and at least one visual indicator outside of the housing and fixedly attached to the axle, where the purpose of the visual indicator is to identify a position of the paddle to an observer.