What is the second step when conducting the main drain test?

The main drain test is a crucial procedure in evaluating the performance and functionality of a fire protection system, particularly in ensuring adequate water supply for firefighting purposes. The second step of this process is to open the main drain.

Opening the main drain is essential because it allows water to flow out of the system, thus enabling the assessment of the system's pressure and flow capabilities. Once the drain is opened, it provides immediate data on how the system performs under simulated fire conditions, reflecting the operational readiness of the system and uncovering any potential issues with water supply.

Following this step, it would typically lead to observing and recording the pressure drop, along with other measurements, to analyze the system's efficiency further. Conducting the main drain test in the correct sequence ensures accurate assessment of the fire protection system’s performance.