Fire Extinguisher Ratings – Find Out About Fire Classifications and Fire Extinguisher Ratings

Fire extinguisher ratings are designed to indicatefires, with US classes shown in brackets:
the type of fires they should be used on, and toClass A Fires (also Class A in US)
give an indication of how effective they will be. Any fire involving solid materials such as wood,
Each fire extinguisher rating in expressed as acard, paper, fabric, etc.
series of numbers and letters which indicate theClass B Fires (also Class B in US)
classes of fire they can be used on the size ofClass B fires involve flammable liquids including
fire they are suitable for.kerosene, oils, petrol, paints, diesel, etc.
Different types of fires are classified by differentClass C Fires (comes under Class B in US)
letters, and fire extinguishers ratings may showA separate classification except in US, this
several letters because they can be used oncategory is for flammable gases, including butane,
more than one type of fire.  In terms of the sizemethane, etc.
of fires the extinguisher can be used on, theClass D Fires (also Class D in US)
number gives an indication of this, and generallyThe D Classification is for combustible metals or
speaking, the larger the number, the larger thealloys, such as potassium, magnesium or titanium.
fire that extinguisher can deal with.Electrical Fires (Class C in US)
The numerical part of the fire extinguisher ratingsElectrical fires are sometimes known as Class E in
relate directly to tests carried out to measurethe UK, but this is an error as there is no
their effectiveness.  A wooden crib test is oneseparate classification for electrical fires in the UK.
test that is used to measure how large a fire anClass F Fires (Class K in US)
extinguisher can deal with.  A fire extinguisherSpecifically relates to fires involving deep fat
rating of 13A, for example, indicates that thefryers (fats and oils).
extinguisher was able to put out 1.3m of theFire Extinguisher Ratings:
fire.  The number on a fire extinguisher rating isThe following information shows the classes of
therefore a very accurate indication of what eachfires covered by the different ypes of fire
extinguisher can cope with.extinguisher:
As another example of the numerical rating, theMain fire extinguisher ratings shown refer to UK,
test for measuring the effectiveness ofwith US ratings in brackets.
extinguishers for use on flammable liquids refersWater Fire Extinguishers:
to the approximate area of fire in square feetClasses of fire: A
that it is able to extinguish.  The specific tests(class A in US)
vary with the different fire types, but the basicCarbon Dioxide Fire Extinguishers:
system of accurately measuring theClasses of fire: Electrical fires, A, B and C
extinguisher’s effectiveness is the same.(A, B and C in US)
It would seem obvious to think that the numberDry Powder Fire Extinguishers:
on a fire extinguisher would increase with the sizeClasses of fire: A, B, C and Electrical fires
of the extinguisher.  This is generally true, but(A, B and C in US)
size is not the only factor that effects theWet Chemical Fire Extinguishers:
number in the fire extinguisher rating.  WithClasses of fire: A, F
water fire extinguishers, additives are often mixed(A and K in US)
with the water to increase their effectiveness,Foam Fire Extinguishers:
therefore you could have two extinguishers whichClasses of fire: A and B
are the same size, but which have different(A and B in US)
numerical ratings, because one is more effectiveFire Extinguisher Ratings - Conclusions
than the other.Understanding fire classes and fire extinguisher
Fire Classifications – The UK and USratings is important in order to be sure of using
Differencesthe correct type of fire extinguisher on any fire in
As already mentioned, the letters used in fireyour workplace.  It can be very dangerous to
extinguisher ratings refer to the classes of fireuse the wrong type of fire extinguisher on some
that they can be safely used on.  We thereforefires, one of the most obvious examples being
need to look at these fire classifications first,the use of water on an electrical fire.  For this
before looking at the actual fire extinguisherreason proper staff training is important for any
ratings for the various types of fire extinguisher.staff who are required to use fire fighting
1. The following are the main classifications ofequipment.