© 2012 Copyright, Phil Ackland and Associates Understanding Commercial Kitchen System Fires Sponsored by the Calgary Fire Department May 28-29, 2012 1

© 2012 Copyright, Phil Ackland and Associates

Understanding Commercial Kitchen

System FiresSponsored by the Calgary Fire

DepartmentMay 28-29, 2012

1


Seminar Overview

• Review of Manual• Review of major

components of exhaust and suppression systems

• Investigation techniques• Review TOC


Who are You?

• Public or Private Fire Investigators

• Inspectors• Contractors• Insurance• Others


Restaurants Burn*

• 1000’s of restaurant fires every year

• The source of a large portion is the kitchen


Commercial Kitchen Fire*

• Many fires are a result of inadequate inspection

• Beyond Arson or Accident

• What can be learned?


Ultimate Goal

• Our ultimate goal is Fire Prevention

• Investigation Helps Us…

• Why did it happen?• How?• What can be done to

prevent it in the future?


Ignition Starts Here

• Nearly all uncontrolled fires will start on the appliances

• This seminar will consider many possibilities


Primary Safety Breakdowns

• Construction

• Installation

• Maintenance


Two Most Common Contributors

Clearances to Combustibles

Excess Grease Accumulation


Clearance Failure

• Failure to keep adequate distances from combustible building materials


Cooking By-Products

• Grease vapor accumulation is one of the most serious hazards


The Grease Process

• Grease vapors contain water molecules (steam) mixed with evaporated fats & oils

• Particles of this mixture are called aerosols


The Grease Hazard

• The higher the temperature, the more grease is transformed into a vapor state

• As the vapor cools, it condenses into a chemically altered solid state

• This grease residue (altered oils) is combustible

• The exhaust system actually becomes a fire hazard


Grease Categories??

• Stir-fry / Deep-fry• Element cooked

– Broilers

– Grills

– Stove tops. Etc.


Solid Fuel Grease

• Solid fuel is used to charbroil meat

• Meats creates high volumes of grease.

• Solid fuel poses the additional problem of ash that mixes with the grease from the meat to create unusually large volumes of buildup.


Deep Fryer Grease

• Translucent creosote• Frozen food (large

amount of water)• Shiny appearance• Hard as multiple

layers of shellac


Asian Grease

• Very sticky, syrup-like liquid

• Honey/molasses consistency


Grease Buildup on Suppression Systems

• One of primary causes of malfunction

• Will not function even if installed correctly

• Staff must monitor condition

• Service company called


• A comparison of block of grease on left to what is under the grease on right.

• This was the duct protection above a charbroiler.

• This picture was taken just after the fire-extinguishing system was allegedly serviced.


Grease on Fire Suppression

• A completely impacted extinguishing system in the plenum of an oriental kitchen.


Grease on Nozzle

• Grease accumulation on a nozzle over a chain broiler.


How Kitchen Fires Can Start/Spread

• Abnormal event on cooking surface• Commonly, cooking oil vapors are ignited by

flames or excess heat• Flare ups create high flames that reach to the

hood and filters• If the heat and exposure time are sufficient

(approx 2 minutes) • Flame impingement will ignite residual grease

in hood and exhaust systems


Fire Spread is Twofold

• First, ignition of grease accumulation in exhaust system.– Oxygen is always present – Flare up (high temperature)– Flare up from an appliance (source of ignition)– Grease residues evaporate & then (ignite point

of ignition)


Spread

• Second, ignition of combustible materials (generally wood building materials or cardboard storage containers) too close to the radiant heat energy being emitted from the metal exhaust duct.


• High air velocity

• Consistency of grease

• Lack of flame impingement from original fire

• Exhaust fan can feed or “blow out” the fire

• Carbon/oil content & the volume of grease

• Deny grease fire sufficient energy


Summary

• Cooking appliances produce grease laden vapors

• Exhaust fan draws vapors and room air into the hood & duct exhaust system

• Grease vapor condenses on the surfaces throughout the exhaust system

• Appliance malfunction or human error produce flare-ups


Summary

• Flame can have sufficient energy to ignite grease residue on filters and hood (~2 min.)

• Once ignited, several factors will determine severity and continued combustion

• Fuel and Oxygen are usually the key factors


Summary

• If there is sufficient fuel, air movement provided by the fan will supply all the oxygen necessary.

• Therefore, it is the abundance of fuel (grease) that most often increases the severity of a fire and creates the radiant heat that may ignite building structures.


Review

2 main areas of issue

Greater sources of grease accumulation

Documents

© 2012 Copyright, Phil Ackland and Associates Understanding Commercial Kitchen System Fires Sponsored by the Calgary Fire Department May 28-29, 2012 1