SPRINKLER CHARACTERISTICS ACCORDING TO NFPA 13

Pipe Schedules for Sprinklers Above & Below Ceiling

Pipe Schedules for Sprinklers Above & Below Ceiling

What are pipe schedules?!

Pipe schedules are used for sizing of firefighting sprinklers system piping in "pipe schedule method" which is used to determine the system demand.

For more information about pipe schedule method for determining sprinkler system demand, please click here.

Pipe schedules per each hazard degree

NFPA 13 classifies the occupancies according to the quantity and combustibility of contents, the expected rates of heat release, the total potential for energy release, the heights of stockpiles, and the presence of flammable and combustible liquids as the followings:

1. Light hazard occupancies. 
2. Ordinary hazard group (1) occupancies
3. Ordinary hazard group (2) occupancies
4. Extra hazard group (1) occupancies
5. Extra hazard group (2) occupancies
6. High piled storage occupancies

NFPA 13 requires concealed spaces of exposed combustible  construction to be sprinklered, in this case we have to follow pipe schedules for sprinklers above & below ceiling.

For more information about concealed spaces requiring sprinklers, and cases to omit sprinklers in concealed spaces, please check it in NFPA 13, clause "9.3.17.1".

below we will explain the pipe schedule for above and below ceiling per each hazard degree:

For light hazard occupancies:

The maximum number of above & below ceiling sprinklers on a given pipe size on one floor is as the following table:

Light hazard pipe schedule for above and below ceiling sprinklers

Note that: Where the total number of sprinklers above and below a ceiling exceeds 50 sprinkler, the pipe shall be increased to 3 in. and sized thereafter according to the table for sprinklers below ceiling for the number of sprinklers above or below a ceiling, whichever is larger.

Light hazard pipe schedule for sprinklers below ceiling

For example: 21∕2 inch steel pipe, which supplies 30 sprinklers, can supply a total of 50 sprinklers where not more than 30 sprinklers are above or below a ceiling.

For ordinary hazard occupancies:

The maximum number of above & below ceiling sprinklers on a given pipe size on one floor is as the following table:

Ordinary hazard pipe schedule for above and below ceiling sprinklers

Note that: Where the total number of sprinklers above and below a ceiling exceeds 60 sprinklers, the pipe supplying such sprinklers shall be increased to 31∕2 in. or larger and sized thereafter according to the table for sprinklers below ceiling for light or ordinary hazard occupancies for the number of sprinklers above or below a ceiling, whichever is larger.

Ordinary hazard pipe schedule for sprinklers below ceiling

For example: 3 inch steel pipe, which supplies 40 sprinklers in an ordinary hazard area, can supply a total of 60 sprinklers where not more than 40 sprinklers protect the occupied space below the ceiling.

For extra hazard occupancies:

Extra hazard occupancies shall be hydraulically calculated.

References of this article:

NFPA 13 - 2019 edition (Standard for the Installation of Sprinkler Systems)

Read Also:

SPRINKLER CHARACTERISTICS ACCORDING TO NFPA 13

SPRINKLERS IN ELECTRICAL ROOMS ACCORDING TO NFPA 13

FIRE DEPARTMENT CONNECTION ACCORDING TO NFPA 13

SEISMIC SEPARATION ASSEMBLY

RETURN BEND REQUIREMENTS ACCORDING TO NFPA 13

SPRINKLER DISTRIBUTION IN SMALL ROOMS - NFPA 13

SPRINKLER PIPING SLOPE REQUIREMENTS - NFPA 13

AUXILIARY DRAIN FOR FIREFIGHTING SPRINKLER SYSTEM

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