NICET Level 1 Water Based Systems Practice Exam

The main difference between a wet pipe and a dry pipe sprinkler system lies in the contents of the piping and how they react in the event of a fire. In a wet pipe system, the pipes are filled with water at all times. This allows for immediate water discharge upon activation, which is advantageous in situations where a Fire is detected, as it provides a quick response to suppress the fire.

In contrast, a dry pipe system contains air or nitrogen under pressure and only releases water when the sprinkler heads are activated. When a sprinkler head is triggered due to heat from a fire, the air pressure in the pipes drops, which opens a valve that allows water to flow from a separate storage area into the pipes and subsequently out of the activated sprinkler heads. This design is primarily used in environments where the potential for freezing water in the pipes exists, such as unheated buildings in colder climates.

This fundamental difference in operation and design is critical for understanding how each system functions in various conditions and environments.