What specific information should be documented on a timed pressure drop test when conducted at the range?

The correct choice emphasizes the importance of accurately recording the manometer measurement and the duration of the test during a timed pressure drop test. The manometer provides critical data regarding the pressure levels in the system being tested, allowing technicians to assess whether the system maintains or loses pressure adequately over time. Tracking the duration of the test is equally critical as it indicates how long the test was performed, which is essential for evaluating the system's performance under a specific timeline.

The combination of these two elements—the manometer reading and test duration—offers a comprehensive view of the system's reliability and efficiency. Proper documentation of these parameters is vital for ensuring compliance with safety standards and for troubleshooting any potential leaks or pressure issues that may arise.

In contrast, while documenting cylinder pressure and test duration, ambient temperature and pressure, or gas type and supply source can be useful for various logistical or operational purposes, they do not directly inform the effectiveness of the timed pressure drop test itself as much as the manometer measurement and duration would.