2.3.2 Looped System
A looped system is a sprinkler system where multiple cross mains are
connected, but the branch lines are not.
City Water Main
Water Meter
Domestic Cold Water
Domestic Hot Water
Fixtures
Service Line
Fire Protection
To Domestic
Hot Water
Fig. 2.6: Looped system layout
2.3.3 Straight-run System
A straight-run system, also known as a tree-type system, is a
sprinkler system in which each sprinkler is served by only one water
fl
ow path.
City Water Main
Water Meter
Domestic Cold Water
Domestic Hot Water
Fixtures
Service Line
Fire Protection
To Domestic
Hot Water
Fig. 2.7: Straight-run system layout
2.4 Design Considerations
The critical points in design of an NFPA 13D and IRC P2904 sprinkler
system are:
- Identify local jurisdiction requirements, including determination of
pertinent building,
fi
re protection and plumbing codes.
- Obtain residence characteristics.
- Identify the water supply source and available
fl
ow in GPM and
supply pressure in psi.
- Identify the water supply service line including elevation difference
between connections and routing of the service line into the
residence.
- Determine the speci
fi
cations for the sprinklers including water
fl
ow
and operating pressure requirements and coverage area
speci
fi
cations.
- Lay out the piping system in the residence as a looped, gridded or
straight-run system as de
fi
ned by NFPA 13D.
- Lay out the piping system for cold and hot water distribution.
- Perform the hydraulic calculations on the system to determine
system performance.
- Coordinate
fi
re sprinkler installation with other building trades to
minimize installation/scheduling con
fl
icts. Verify installation of
sprinkler system per plan (includes sprinkler locations and proper
mounting height).
- When the
fi
re sprinkler system connects to plumbing
fi
xtures it is
required to comply with prevailing local plumbing codes.
NOTICE
The FIREPEX system shall not have a
fi
re department connection and
the static pressure of the system shall be limited to 80 psi. If the
static pressure of the water supply is not less than 80 psi then a
pressure reducing valve set no higher than 80 psi shall be used.
When a pressure reducing valve is required then an automatic means
of pressure relief shall be installed on the sprinkler system side of the
pressure reducing valve.
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