ASHRAE Journal - February 2015 - 22

TECHNICAL FEATURE

water damage throughout the building. A variety of
additional fire and mechanical code violations were
observed.
Other observations. At several fire sites, there were
large accumulations of grease in appliances, hoods, and
ducts. Several ducts had imperfect welds and were not
liquid tight, and required duct accesses for cleaning
were often lacking and/or leaking.

Fire Cases From Official Reports
Solid fuel fire at full-service restaurant in airport
terminal. A fire ignited in a hood and duct over a solid
fuel charbroiler and a solid fuel rotisserie. The fire
inspector's report included these observations:3
* Fire occurred in plenum and duct of solid fuel cooking appliance hood;
* Grease filters had build-up of ash and grease;
* Extensive charring and ash in plenum of hood; and
* Grease build-up on wall under hood.
Firefighters extinguished the fire with limited damage, and although the gas cartridge seal was found punctured, the fire inspector noted several issues with the
fire system:
* Hood suppression release mechanism in cabinet
indicating (sic) discharge;
* Manifold piping burst disk unaltered, indicating no
discharge of liquid; and
* Chemical suppression agent tanks full.
From the inspector's observations, it's likely the gas
cartridge was previously used or it was improperly
installed in the release mechanism, either of which suggests improper maintenance of the system.
Partial damage from solid fuel cooking fire.
According to the fire report:4 "The cook said when the
fire in the pit got going, a fire started in the flue (duct).
He was able to put the fire out in the pit and tried to put
the fire out in the flue with his extinguisher. The flue
fire wouldn't go out." The report implies that the fire
suppression system activated but did not extinguish the
fire in the duct.
Partial damage of bowling center snack bar. A fire
ignited in the cooking area of a bowling center snack bar,
reportedly from a deep fat fryer, and it spread upward
into a long vertical duct. According to the fire marshal's
report:5
* FM (fire marshal) arrived on scene and found fire
coming from the hood exhaust fan on the roof;
22

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FEBRUARY 2015

FIGURE 1 Typical placard for mounting over Type K extinguisher.

* The suppression system operated but did not extinguish the fire; and
* Witnesses advised hood suppression activation
seemed to be delayed.
The author's opinion is that the fire, aided by exhaust
airflow, spread upward into the long vertical duct
quicker than the suppression system could act on it.

Other Cases
Appendix B of Reference 1 includes brief summaries
of 13 fire incidents in eating and drinking establishments. The descriptions include five incidents in which
hood fire suppression systems did not operate, or did
not operate properly. In one case, the suppression system put out the fire under the hood, but the fire continued in the duct and was eventually extinguished by
firefighters.

Lessons Learned
Here's a summary of lessons learned from the fires
described above, published reports, and fire scene
observations by the author.
Fire training. Restaurant workers must be trained
in fire protection and suppression procedures, including: activating fire alarms and/or calling 911; manual
activation of fire suppression systems; optional use of
Type K, not ABC extinguishers; and orderly evacuation of themselves and customers. As shown in Figure
1, a required placard mounted over Type K liquid fire
suppressant extinguishers warns that fire suppression
systems should be manually activated before use of Type
K extinguishers.

ASHRAE Journal - February 2015

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