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This Presentation Developed By Drew 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. The New Class. Class K. Background.

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This presentation developed by drew r smith

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.


The new class

The New Class

Class K


Background

Background

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

Class K Fires & Portable Extinguishers


Fryers

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

Class K Fires & Portable Extinguishers


Cooking media

Cooking media

  • Older fryers used animal fat

  • Newer fryers use vegetable oil

    Vegetable oils cook at higher temperatures than animal fat

Class K Fires & Portable Extinguishers


This presentation developed by drew r smith

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

Class K Fires & Portable Extinguishers


This presentation developed by drew r smith

  • 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 50°F lower before

New AI Temp

AI Temp

ROOM TEMP

HEATED

Class K Fires & Portable Extinguishers


This presentation developed by drew r smith

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

Class K Fires & Portable Extinguishers


A new class of fire is born

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)

Class K Fires & Portable Extinguishers


This presentation developed by drew r smith

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

Class K Fires & Portable Extinguishers


This presentation developed by drew r smith

  • 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 oil’s surface

  • This soap foam performs just like regular firefighting foam to secure vapors and extinguish the fire

Class K Fires & Portable Extinguishers


This presentation developed by drew r smith

When dry chemical is used to create this saponification it will not cool all of the oil in the fryer

Class K Fires & Portable Extinguishers


Wet chemicals liquids that contain an alkaline agent are more effective

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

Class K Fires & Portable Extinguishers


Ul tests verify this

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

Class K Fires & Portable Extinguishers


This presentation developed by drew r smith

  • 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 oil’s temperature was below 60°F

Class K Fires & Portable Extinguishers


As a side note

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

Class K Fires & Portable Extinguishers


This presentation developed by drew r smith

  • 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

Class K Fires & Portable Extinguishers


Class k fire extinguishers

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

Class K Fires & Portable Extinguishers


This presentation developed by drew r smith

Wet Agent units are available in both 1&1/2 and 2&1/2 gallon units

Both the 1&1/2 and 2&1/2 gallon units carry 2-A:1B ratings

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

Class K Fires & Portable Extinguishers


Fire department operations

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

Class K Fires & Portable Extinguishers


Remember

REMEMBER

Wet agents works by cooling AND saponification

Class K Fires & Portable Extinguishers


References

References

  • “The New Class”, J. Craig Voelkert, NFPA Journal, July/August 1999

  • NFPA 10 - Standard for Portable Fire Extinguishers, 1998 Edition

Class K Fires & Portable Extinguishers


The end

The End

Class K Fires & Portable Extinguishers


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