Which statement about wet-pipe sprinkler systems is true?

Which statement about wet-pipe sprinkler systems is true?

• A. They require nitrogen-filled pipes to operate.
• B. They have water-filled pipes at all times.
• C. They release water only after a two-stage event.
• D. They do not use water in the piping until activated.

Answer: (B)

Wet-pipe systems have water-filled piping ready to deliver immediately. When a sprinkler head is heated and activates, water flows through the already-filled pipes and out the open head right away. That immediate release is the defining feature, which is why the statement stating the pipes are water-filled at all times is true. The idea of nitrogen-filled pipes is associated with dry systems, where pipes are kept with air or nitrogen to prevent freezing and corrosion, not with wet-pipe. A two-stage release would imply a delayed or staged valve operation (not typical for standard wet-pipe systems). And the notion that the piping contains no water until activation contradicts how wet-pipe systems operate, since they are always filled with water.

Wet-pipe systems have water-filled piping ready to deliver immediately. When a sprinkler head is heated and activates, water flows through the already-filled pipes and out the open head right away. That immediate release is the defining feature, which is why the statement stating the pipes are water-filled at all times is true.

The idea of nitrogen-filled pipes is associated with dry systems, where pipes are kept with air or nitrogen to prevent freezing and corrosion, not with wet-pipe. A two-stage release would imply a delayed or staged valve operation (not typical for standard wet-pipe systems). And the notion that the piping contains no water until activation contradicts how wet-pipe systems operate, since they are always filled with water.