This Presentation Developed By Drew R. Smith

1
This Presentation Developed ByDrew R. Smith

• This presentation may be modified or reproduced
  by individual fire departments or training
  organizations provided it is not used to generate
  revenue or in any commercial manner.

2
The New Class

• Class K

3
Background

• In the past ten years or so there has been a
  major change in commercial cooking involving
  deep-fat fryers and cooking medias

4
Fryers

• Older deep-fat fryers were either uninsulated or
  lightly insulated
• Newer deep-fat fryers are well insulated
• Thus, older fryers cool faster than newer fryers

5
Cooking media

• Older fryers used animal fat
• Newer fryers use vegetable oil
• Vegetable oils cook at higher temperatures than
  animal fat

6

• Unlike gasoline, paint thinner and other
  flammable liquids, cooking oils have a wide
  auto-ignition temperature range

7

• When cooking oils heat beyond their auto-ignition
  temperature the oil changes composition resulting
  in an oil than now has an auto ignition
  temperature as much as 50F lower before

AI Temp
New AI Temp
ROOM TEMP
HEATED
8

• Unless the entire amount of oil cools below this
  new auto-ignition temperature the fire will
  reflash and burn

9
A new class of fire is born

• NFPA 10 defines Class K as
• Fires in cooking appliances that involves
  combustible cooking media (vegetable or animal
  oils or fats)

10
Dry Chemical Agents sodium bicarbonate or
potassium bicarbonate, when applied to burning
cooking oils create a chemical reaction known as
saponification
11

• All cooking oils, greases and fats contain free
  fatty acids (saturated fat)
• When added to a free fatty acid, alkaline
  extinguishing agents (such as sodium bicarb or
  potassium bicarb) form a soap foam on the oils
  surface
• This soap foam performs just like regular
  firefighting foam to secure vapors and extinguish
  the fire

12
When dry chemical is used to create this
saponification it will not cool all of the oil in
the fryer
13
Wet chemicals (liquids) that contain an alkaline
agent are more effective

• Agents may contain potassium acetate, potassium
  citrate and/or potassium carbonate
• Applied in a fine mist the agents cool and form
  the saponification
• These to action cool the oil to below its
  auto-ignition temperature

14
UL tests verify this

• UL conducted dozens of tests comparing Class
  B-rated dry chemical portable fire extinguishers
  with these new Class K wet agent portable fire
  extinguishers
• Tests showed that an 80B (20) extinguisher that
  put out a 200-square foot pan fire could not put
  out a deep-fat fryer with only a 2? sq-foot
  surface

15

• The Dry Chem knocked the fire down (with a big
  dust cloud) only to reignite
• The Wet Agent fully extinguished the fire for at
  least 20 minute or until the oils temperature
  was below 60F

16
As a side note...

• Wet agents can be found in both permanent systems
  and portable fire extinguishers
• They are applied using fine mist nozzles to
  reduce splashing
• Most permanent kitchen extinguishing systems
  display a permanent making stating the equipment
  is UL300-compliant

17

• NFPA 10 requires that a portable Class K fire
  extinguisher only be used AFTER the installed
  system is activated
• When a Class K portable fire extinguisher is
  installed in a restaurant there is to be a sign
  above it stating this requirement

18
Class K Fire Extinguishers

• Also carry a class A B rating
• Class K rating does not carry a number value such
  as class A B ratings

19

• Wet Agent units are available in both 11/2 and
  21/2 gallon units
• Both the 11/2 and 21/2 gallon units carry
  2-A1B ratings

• While dry-agent Class K extinguishers are
  available, this program focuses on wet-agent
  extinguishers

20
Fire Department Operations

• Recognize the situation and the need for the
  Class K fire extinguisher
• Activate the installed system first
• Wearing full protective gear, apply the wet agent
  from the portable fire extinguisher
• Apply all the agent in the extinguisher EVEN if
  the fire appears to be out

21
REMEMBER

• Wet agents works by cooling AND saponification

22
References

• The New Class, J. Craig Voelkert, NFPA Journal,
  July/August 1999
• NFPA 10 - Standard for Portable Fire
  Extinguishers, 1998 Edition

23
The End