What is the purpose of a drain test on a wet-pipe system?

• A. To verify proper drainage path and ensure no water remains in the piping after discharge.
• B. To verify the drainage pipe diameter
• C. To test alarm signaling timing
• D. To confirm the presence of a drain trap

Answer: (A)

In a wet-pipe system, the piping is filled with water, so when a sprinkler head releases, that water must be able to leave the line through a proper drainage path. The drain test checks that the discharge has a clear route to the drain, that there are no obstructions, and that the water in the piping empties promptly after discharge. This ensures no residual water remains in the system, which could cause damage, corrosion, or delay future activations.

This test isn’t about choosing the correct pipe diameter, timing of alarms, or confirming the presence of a drain trap; those are separate aspects of system testing.