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7/29/2019 Fire Extinguishers Rating SHORT

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Fire Extinguishers Rating


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Extinguisher Rating Numerical rating given to Class A and B

extinguishers which indicate how large a

fire an experienced person can put out with

the extinguisher

Ratings are based on tests conducted at

Underwriters Laboratories, Inc.

Class A: 1-A, 2-A, . . . 40-A

Class B: 1-B, 2-B, . . . 640-B

A 4-A extinguisher, for example, should

extinguish about twice as much fire as a 2-A

extinguisher


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Fire Extinguishers Rating

Unlike some products, extinguishers have tobe installed in public premises, and a

standard form of assessment is required todetermine how many extinguishers andwhat type are needed to protect a given risk.

There are two main rating systems:

CEN (European System)

U.L. (American System)


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CEN European System

Class A Fire Extinguishers

Crib of wooden sticks. All cribs are 0.56 meters high and 0.5 meters wide, but the length

varies for specific ratings. For example the length is 0.3 m for 3A

& 5.5 m for 55 A.

A tray containing Heptane is placed under the crib to light thefire.(The test fires are located indoors.)

After 2 minutes the try is removed, Fire allowed to burn for 6

minutes.

For the test to be successful it is essential that all flames should beextinguished and there should be no recurrence of flaming during

the three minutes following the complete discharge of the

extinguisher.

2 tests out of 3 succeeded

Ext. passed the test


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Class A Fire Tests


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Class A test fireSide view

showing 13A fire


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Class A Test Fire


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Length of Wooden Curbs

Rate Length of Wooden Curbs3A 0.3 meter

5A 0.5 meter

8A 0.8 meter13A 1.3 meter

21A 2.1 meter

27A 2.7 meter

34A 3.4 meter

43A 4.3 meter

55A 5.5 meter


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Class BFlammable Liquids

Tests are conducted in a range of welded sheetcircular cylindrical trays.

Each tray in the series is designated by a numberrepresenting the amount of fuel required in liters as inthe table.

The fuel is Heptane.

The fire is allowed for 1 minute pre-burn. The wind speed should not be greater than 3m/sec.

And ambient temp. between 0 30 degree C.

2 tests out of 3Ext. succeeded.


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Class B Tests


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Rating Volume of Fuel in Liter

8B

13B

8 liters

13 liters

21B

34B

21 liters

34 Liters

55B

70B

55 liters

70 Liters

89B

113B

89 liters

113 Liters

144B

183B

233B

144 liters

183Liters

233 Liters


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U.L. Rating System

Class A Fire Test WoodCrib Fire Test:

Tests up to 10A in draft free room.

For rating class exceeding 10A the test may

be conducted outdoors .

A test fire shall be considered to be

extinguishedno self re-ignition.

2 tests out of 3ext. succeeded.


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Class A Fire Test


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Dimension of Wooden Curbs

Rate # of

Sticks

Dimension

In millimeter

# of

Layer

s

# of

Sticks in

each

layer

1A 50 45X45X500 10 5

3A 98 45X45X600 14 7

6A 153 45X45X1000 17 9

10A 209 45X45X1220 19 11

20A 150 45X65X1500 10 15


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Class B Fire Test

Flammable liquid fire tests are to be

conducted in a large volume draft-free room

for a rating 20B. For more than 20B rating is conducted

outdoor.

Tests to be conducted in square shape trays.


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Class B Fire Test


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Class B Fire Test

Rating Volume of Fuel

1B 12 LITER

10B 120 LITER

20B 250 LITER

30B 350 LITER

40B 475 LITER60B 720 LITER

80B 950 LITER


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Outdoor Tests

120-B 375 gallons

160-B 500 gallons

240-B 750 gallons

320-B 1000 gallons

480-B 1500 gallons

640-B 2000 gallons

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