Which device is primarily used to relieve pressure and drain water from irrigation lines during service?

• A. Mainline isolation valve
• B. Drain valves
• C. Unions
• D. Grounding

Answer: (B)

Relieving pressure and draining water during service requires a dedicated path to release the water trapped in the lines. Drain valves provide that path. Installed at low points or near the mainline, they are opened after the water is shut off so any remaining pressure and water can escape safely. This makes it easier to disconnect components, protects fittings from pressure shock, and helps prevent freezing damage in cold weather.

The mainline isolation valve serves to stop flow to a section of the system, which is important for safe work, but by itself it doesn’t drain the line. Unions are fittings that connect and disconnect sections of pipe, not drainage devices. Grounding relates to electrical safety and has no role in removing water from irrigation lines.