Standard fire

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Logo of the German Institute for Standardization DIN EN 3-7
Area Portable fire extinguishers
title Part 7: Properties, performance requirements and tests
Latest edition 2007
ISO

The standard fire is in EN 3-7, Annex I, L or NA standardized Prüffeuer for testing fire extinguishers . There are standard fires of the fire classes A, B, D and F standardized in EN 2 .

The assignment and testing of the extinguishing capacity of each fire extinguisher is regulated on the basis of test objects of different sizes ( extinguishing objects ). The largest test object that can still be extinguished with the fire extinguisher defines its maximum extinguishing capacity (rating). Since this can differ depending on the type of fire of the test object, it is determined separately for each fire class.

Each test object is given an abbreviation that describes the type and size of the standard fire.

Class a

The class A standard fire is a burning pile of wood stacked on a 250 mm high metal frame . This consists of 14 layers of evenly stacked wooden sticks made of pine wood , 60 mm apart, with a cross-section of 39 mm × 39 mm. The height is about 560 mm. The depth of this stack of wood is 500 mm, while the width can be varied. The higher the extinguishing capacity of the extinguisher should be, the wider the standard fire. This stacking results in the same number for the width in decimeters as the number of wooden sticks that are lined up next to each other in every second layer. The number of wooden sticks in the intermediate layers is a uniform 5 sticks per layer, these sticks being adapted to the width of the fire.

Each test object is given an abbreviation that indicates the type and size of the test object.

The abbreviation 27A means:

  • Fire class A (solid fire)
  • 2.7 m width
  • 27 wooden sticks each 50 cm long, lined up next to each other in every second layer.

According to the standard, there are test objects 5A (500 mm) , 8A (800 mm) , 13A (1300 mm) , 21A (2100 mm) , 27A (2700 mm) , 34A (3400 mm) , 43A (4300 mm) , 55A (5500 mm) .

For the test, an ignition pan filled with 30 mm of water is pushed under the metal frame on which an amount of heptane is layered in such a way that a burning time of 150 s is achieved. After a pre-burning time of 2 minutes, the ignition pan is removed, the pile of wood is left to burn for a further 6 minutes, after which the attempt to extinguish must be started and completed within max. 7 min (max. 5 min for test objects up to and including 21A).

class B

The standard fire class B is a cylindrical sheet steel container in which heptane and water are filled in a ratio of 2: 1 so that the height of the water column is 10 mm and that of the fire liquid column is 20 mm. These are mixed. The diameter of the container is variable and increases with the required extinguishing capacity. The amount of mixture filled in liters corresponds to the number of extinguishing capacity achieved by the fire extinguisher, provided that it has extinguished the object.

Each test object is given an abbreviation which indicates the type of test object and the amount of fuel filled in as described above.

The abbreviation 233B means:

  • Fire class B (liquid fire)
  • approx. 155.3 liters of fuel (filled 20 mm high) and the corresponding amount of water of approx. 77.7 liters

According to the standard, the test objects there are 21 B , 34B , 55B , 70B , 89B , 113B , 144B , 183B and 233B .

Class D.

The standard fire class D (national specification for Germany) consists of two fire objects which must be completely extinguished with the same extinguisher charge:

a) 3 kg of chips of a light metal alloy with a magnesium content of approx. 85 percent by mass are ignited in a square sheet steel tub, the extinguishing attempt begins as soon as about half of the chips are burning

b) 3 kg of sodium are poured into the same tub and heated until the sodium continues to burn by itself.

After completing these tests, the fire extinguisher is considered suitable for extinguishing aluminum, magnesium and their alloys as well as sodium and potassium and may be labeled accordingly. A suitability for other metals must be proven separately.

Class F

The class F standard fire is a sheet steel container (the exact nature of which varies depending on the extinguishing capacity which is to be tested) in which food- vegetable oil is filled and heated until it spontaneously ignites. After self-ignition, the heat source is switched off and the oil is allowed to burn for 120 s. Then the fire fighting will begin.

The number attached to the designation of the extinguishing capacity indicates how many liters of burning cooking oil can be extinguished. When attempting to extinguish the fire, no burning material may be thrown out of the container, the fire may not re-ignite after extinguishing and the flames may not be enlarged. The fire extinguisher must be emptied without interruption

Each test object is given an abbreviation which indicates the type of test object and the amount of fuel filled in as described above.

The abbreviation 75F means:

  • Fire class F (fat fire)
  • 75 liters of burning cooking oil

According to the standard, there are test objects 5F , 25F , 40F and 75F .

literature

  • Ekkehard Richter, Richard Jenisch, Hanns Freymuth, Martin Stohrer: Textbook of building physics. Sound - heat - humidity - light - fire - climate. 6th edition. Vieweg + Teubner Verlag, Stuttgart / Leipzig / Wiesbaden 2008, ISBN 978-3-519-45014-6 .
  • Ulf-Jürgen Werner: Structural fire protection. Planning - dimensioning - execution, Springer Verlag, Basel 2004, ISBN 978-3-0348-9596-5 .
  • Konrad Bergmeister, Frank Fingerloos, Johann-Dietrich Wörner (eds.): Concrete calendar 2009. Ernst & Sohn Verlag, Berlin 2009, ISBN 978-3-433-01854-5 .

Web links