Which system piping contains air or nitrogen under pressure at all times?

Which system piping contains air or nitrogen under pressure at all times?
A . Standard dry-pipe system
B . Wet-piping system
C . Preaction system
D . Deluge system

View Answer

Answer: A

Explanation:

The various sprinkler systems are differentiated by the type of fluid or gas in the piping and how they operate:

Standard dry-pipe system (A): Contains air or nitrogen under pressure in the piping at all times. When a sprinkler activates, the pressure is released, allowing water to flow into the pipes and out of the sprinkler heads.

Wet-piping system (B): Contains water in the piping at all times.

Preaction system (C): Contains air or nitrogen under pressure, but water is introduced only when specific detection systems activate.

Deluge system (D): Piping is normally dry, and all sprinklers open simultaneously when a detection system triggers water flow.

Reference: NFPA 13, Chapter 7: Types and operation of sprinkler systems.