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Sprinkler Piping Slope Requirements - NFPA 13

Slope Requirements For Sprinkler Piping According to NFPA 13 - 2019 edition


Sprinkler Piping Slope According to NFPA 13
Sprinkler Piping Slope According to NFPA 13


According to NFPA 13 - 2019, all sprinkler pipe and fittings shall be installed so that the system can be drained.

Slope requirements shall be according to each system type as the followings:


1- for wet type sprinkler system:

  • No slope required.
  • Trapped piping shall be drained using auxiliary drain

To know the requirements and components of auxiliary drain, please visit the link below:AUXILIARY DRAIN FOR FIREFIGHTING SPRINKLER SYSTEM


2- For dry and pre-action pipe systems in non-refrigerated areas:

  • Branch lines shall be pitched at least 1⁄2 in. per 10 ft (4 mm/m).
  • Mains shall be pitched at least 1⁄4 in. per 10 ft (2 mm/m).


3- For dry and pre-action pipe systems in refrigerated areas:

  • Branch lines shall be pitched at least 1⁄2 in. per 10 ft (4 mm/m)
  • Mains shall be pitched at least 1⁄2 in. per 10 ft (4 mm/m)

Why do we pitch sprinkler piping in dry and preaction systems?

Because dry pipe systems and preaction systems are usually installed in areas subject to freezing, proper drainage is critical due to the potential freezing of a pipe network after a system trip. Water trapped in the pipe network can begin to freeze in a matter of minutes in systems installed in structures that maintain temperatures at or below 0°F (−18°C). It should also be noted that where water is sitting in the belly of the piping system, corrosion will occur at the points where air and water meet along the internal wall of the
pipe.

References of this article:

  • NFPA 13 – 2019 edition (Standard of Installation of Automatic Sprinklers)


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