ASHRAE Journal - February 2015 - 20

TECHNICAL FEATURE

blackened grease on the bottom of
the fire system cabinet.
Damage to fryer area of quick
service restaurant. Investigators
discovered that fire started in
a power distribution assembly
behind multiple electric fryers. One
high power receptacle was found
to be completely disintegrated, and
black "carbon tracking" was visible
on the corresponding white-bodied
power plug. Grease deposits in the
PHOTO 4 Burnt truss near duct (in circle) and loose
PHOTO 5 Burnt grease in area of ignition near hot
receptacle apparently carbonized
fitting thin metal sleeve joint (in rectangle).
burner flue.
and became conductive, forming
an electric short circuit that heated grease deposits suf- ignited in a fryer with its cooking oil level below the level
ficiently to ignite the fire.
of the operating thermostat, leading to continuous heatTotal loss of quick service chain restaurant.
ing. Separate high-temperature limit switches were not
Investigators determined that a grease deflector baffle
operational on three of the four fryer vats, including the
was missing from the fryer hood, such that liquid
burning vat.
grease flowed downward from the hood and duct
From a security video, fire system automatic activation
into the center fryer flue, where it was ignited by the
was delayed about eight minutes, likely because of two
gas burners. The fire system activated but failed to
issues that reduced hood airflow and heating of the fusdischarge suppressant because the propellant gas
ible links:
cartridge was not installed in the release assembly.
* Old, unlisted mesh filters in the fryer hood were
Instead, it was lying on the bottom of the fire system
clogged with grease; and/or
cabinet.
* The fryer exhaust fan was not operating because of
Fire spread was aided by two issues related to the fryer a broken drive belt.
exhaust duct, as shown in Photo 4.
The security video also showed that instead of acti* From a previous remodel, the fully welded steel
vating the manual pull and then optionally using the
duct was cut and extended with a section of thin galvaappropriate Type K extinguisher, workers discharged
nized vent piping, with loose fitting sleeve connections
an ABC extinguisher toward the fire, resulting in an
that allowed fire to escape from the duct into the attic;
unwelcome powder flare-up. Thereafter, workers looked
and
closely at the nearby manual pull station for a few sec* There was insufficient clearance from the duct to
onds, but they did not manually activate the fire system
wood trusses in the attic.
before evacuating the building.
Total loss of quick service restaurant in remodeled
Major damage to an Italian-themed family restauhistoric building. Fire started in the rear of a set of fryrant. Investigators determined from interviews that
ers. The fire was caused by an accumulation of grease
workers placed a larger than normal amount of raw
inside the fryers near the hot gas burner flues, as shown meat onto the hot grates of a gas-fueled charbroiler,
in Photo 5. Some of the grease sprayed toward the flue
causing a large flare-up and ignition of grease in the
area from a cooking oil leak in plastic piping added with hood and its two ducts. Fire likely escaped from the
the installation of a third-party cooking oil disposal and
hood because the hood was not continuously welded
replenishment system. The fire system activated but did liquid-tight, ducts were not properly connected to
not prevent fire spread and loss of the entire historic
the hood, and/or heat in the hood auto-ignited wood
building.
ceiling joists to which the hood was mounted with
Damage to fryer area in a quick service restaurant,
insufficient clearance. Flames burned through the
with significant smoke and water damage. Fire likely
ceiling, attic and roof, and there was smoke and
20

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