The term wet pipe refers to a sprinkler system in which pipes are filled with water at all times.

• A. Wet Pipe
• B. Dry Pipe
• C. Deluge System
• D. Deluge With Air Chambers

Answer: (A)

The key idea is that water is in the piping at all times. In a wet pipe sprinkler system, the pipes themselves are filled with water under pressure so that when a sprinkler head is activated by heat, water is released immediately through that head. This gives the fastest response because there’s no delay waiting for water to fill empty pipes.

In contrast, a dry pipe system keeps the pipes filled with air or an inert gas; water is held back by a valve and must move through the system once the valve opens, causing a brief delay. Deluge systems have all heads connected to the water supply and open pathways to all heads, so water is distributed quickly to all heads once activated, but the piping is not maintained full of water like a wet system. The option involving air chambers isn’t a standard description of a wet pipe arrangement.

So, the description that matches “pipes are filled with water at all times” is the wet pipe system.