NFPA Journal - Summer 2021 - 73

NFPA 13

SPRINKLER DENSITY, RACK STORAGE,
AND ELEVATOR SHAFT PROTECTION
HIGHLIGHT UPCOMING CHANGES
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F OR DECADES, NFPA 13, Standard for the Installation of Sprinkler
Systems, has instructed sprinkler
designers and installers to use what's
known as a density/area curve to
calculate sprinkler density-the measurement of the volume of water
released in a certain amount of time
over a specific area. Given hazard
group classifications, users could
pick any density along a curve. But a
change slated for the 2022 edition of
NFPA 13 would eliminate the curve
method of density calculation for
new sprinkler systems and replace it
with a single-point method of density
calculation.
That's just one of the changes proposed for the upcoming edition of
NFPA 13. Another anticipated change
would put a cap on rack depth for storage facilities, while a familiar debate
over sprinklers in elevator shafts is set
to unfold at the 2021 Association Technical Meeting.
The shift from density/area curves
to a single-point method would be
the most significant change to the
standard, according to Chad Duffy, the
NFPA staff liaison to NFPA 13.
" We're moving away from those
curves and toward very specific density/area points, " Duffy said, adding
that the curves were created based on
data that was as much as 50 years old.
" So you will no longer be able to pick
any point along the curve. Most technical committee members think this
is probably the best direction to go,
especially when it comes to authorities
having jurisdiction. A lot of folks didn't
really understand how you could use
different points on the curve. This will
clean that up and make it easier for
AHJs. "

In addition to simplifying the standard, Duffy said the change would
eliminate any doubt that every single
point on a curve would in fact translate to a sprinkler system performing
as it should. " Not every point on these
curves was proven, " he said. " A lot of
the curve may have been interpolated
from a few data points. I don't think
we have any type of historical data of
fire incidents where we could say we
used a density curve and the sprinkler
system didn't control the fire like it
was designed to. But by moving to a
single-point density method, it removes
any uncertainty that might exist with
the interpolation of the curves. "
Not everyone agrees with the
change. " The curves have been working
for us since the 1970s, " Larry Keeping,
a fire protection engineer and member
of NFPA 13's Sprinkler System Discharge Criteria committee, wrote in
a public comment submitted in April
2020. " The old adage 'If it ain't broke,
don't fix it' comes to mind. "
The committee responded, saying
that " the intent of the single-point
density approach has been to improve
sprinkler performance by selecting the
highest possible discharge density. "

BEYOND SINGLE-POINT
DENSITY
A second change Duffy said is expected
for the 2022 edition of NFPA 13 is a
limit on the depth of multi-row storage racks to 20 feet-an attempt at
preventing fire spread in warehouses.
Currently, the standard doesn't have a
limit on multi-row rack depth.
" Without limitation, the concern is
horizontal fire spread through these
multi-row racks, " Duffy said. " If you
have overhead sprinklers protecting

multi-row racks and they're extremely
deep and you have all that product on
various levels, the sprinklers could be
shielded. "
Representatives from the rack
industry oppose the proposed change.
" This change as currently written will
classify just about every multiple-row
rack in every warehouse as having
solid shelves. Thus ... there would be
an in-rack sprinkler requirement under
every pallet storage level, " Gary Smith,
a member of the NFPA 13 Sprinkler
System Discharge Criteria committee,
who is also senior vice present of sales
and marketing for rack manufacturer
DACS, Inc., wrote in a public comment
in April 2020. The change would be
costly and inevitably lead to more collisions between forklifts and sprinklers,
Smith added.
Despite that industry opposition,
Duffy said no notices of intent to make
a motion (NITMAMs) were filed by the
rack industry.
There are several NITMAMS, however, pertaining to an issue that has
come up many times before during
NFPA 13 cycles, Duffy said, and that's
the debate over whether sprinklers
should be required in elevator pits,
the lowest area of an elevator shaft.
The current edition of the standard
requires spinklers in elevator pits.
The argument in favor of sprinklers
rests on the idea that a lot of debris,
and sometimes even hydraulic fluid,
can accumulate in elevator pits, creating a fire hazard. The argument
against sprinklers, which is the argument largely supported by the elevator
industry, is that installers and inspectors are unnecessarily put in harm's
way when they need to enter elevator
pits. " They want to reduce the number
of people that need to go into those
pits and work based on accident data, "
Duffy said. " They don't see a history of
fires in elevator pits. "
Duffy said he wasn't sure what
will come of the debate during the
technical meeting, but it's something
committee members are used to engaging in. " We have this elevator argument
cycle after cycle after cycle, " he said.
ANGELO VERZONI is staff writer at NFPA Journal.

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