What main valve must be opened to ensure correct conditions before a main drain test?

To ensure correct conditions before conducting a main drain test, the alarm control valve must be opened. The alarm control valve serves as a critical component in fire protection systems because it helps regulate the flow of water in response to fire alarm signals.

Before performing a main drain test, the system needs to be in a state where it can accurately measure the available water flow and pressure. Opening the alarm control valve ensures that the system is operational and allows water to flow freely during the test. This is essential for obtaining reliable results, as the test aims to evaluate the performance of the water supply and verify that it meets necessary pressure requirements.

In contrast, other valves such as the solenoid valve or flow control valve have different functions and do not directly facilitate the correct conditions for a main drain test. A control valve can be somewhat ambiguous, as it might refer to several types of valves that manage the flow, but it specifically does not denote the alarm valve’s role in this context. Therefore, the focus on the alarm control valve as the valve to be opened before a main drain test is crucial for ensuring that the system is ready for accurate measurement during the testing process.