Expert

Extinguishing efficiency
One of the most important factors deciding about possibility of fire extinguishing by means of fire extinguisher is the extinguishing efficiency. On the label of each extinguisher you can find information concerning fire groups which can be extinguished with this extinguisher. Additionally, for fire groups A and B the fire rating must be given, e.g. 8A 113B, which should be extinguished by means of fire extinguisher. Requirements and test course for individual test fires of group A and B have been set by Polish Norm PN-EN 3-1. Such tests are performed by authorized insitutes. Positive test result is one of conditions required for receiving the certificate permitting application of fire extinguisher in fire protection. These tests are performed with application of appropriate safety precautions, for this reason we strongly dissuade you from performing of such tests on your own. Underneath we present basic information concerning methods of determining of extinguishing efficiency on the basis of norm PN-EN 3-1:


Test fire, group A


Properties
Test fire of group A is made by means of wooden sticks arranged as a pile on metal bracket with height of 560 mm, width 500 mm and length equal to length of test fire. Test fire with size bigger than 27 A should be constructed with application of smaller test fire (e.g. 34A = 21A+13A, 43A = 8A+27A+8A). Beams are made of pinetree wood with mass humidity from 10% to 15%. Beams are cut into pieces, they have square cross-section, the side length 39 mm. Beams are to be arranged in 14 layers on the metal bracket frame, as shown on drawings B.1 and B.2. Crosswise beams are of equal length - 500 mm. Lengthwise beams have the length equal to the test fire as shown on table B.2. Test fire exceeding the value 55A is not allowed. Each test fire is marked with a number and following letter A. The numer in description means: - length of test fire in decimeter, i.e. length of wooden beams arranged along the test fire; - number of beams with length of 500 mm, in each layer arranged across the test fire. Table B.2

Carrying out
Test fire should be located in compartment and should be protected against draughts. Test compartment should not hinder natural development of fire and its efficient extinguishing. Ignition tray should have width of 600 mm and depth of 100 mm. Length of tray should be 100 mm longer than the length of test fire. Ignition tray should be located directly under the pile composing the fire. The tray should be filled with water up to the height of 30 mm. Then it is necessary to fill the tray with heptane in amount sufficient for burning for 2 min. 30 seconds. Then the heptane should be ignited. After 2 minutes of burning the tray should be removed from underneath the pile. Then let the pile burn for further 6 minutes, enabling total time of initial burning equal to 8 minutes, after which the test fire is developed and extinguishing can be commenced. Person performing test should actuate the extingusher and direct the stream to the test fire, moving around the fire at will to achieve the best possible result. Total content of extinguisher should be discharged with continuous or intermittent stream. Maximum extinguishing time should not exceed 5 minutes for test fire up to 21A and 7 minutes for bigger fire sizes. In both cases fire should be monitored for further 3 minutes following this moment. Test result is positive, when all flames are extinguished and will not reappear during 3 minutes of observation.

Test fire, group B


Properties
Test fire of group B is made by means of cylindrical trays made of welded metal sheets, with dimensions given in table B.3. Test fire bigger than 233B is not allowed. Each test fire is marked with a number and following letter B, where the number indicates volume of liquid in tray given in litres. Trays should be used with application of water pillow, with following proportions: 1/3 water and 2/3 fuel.

Carrying out
Wind speed should not exceed 3 m/s. As the fuel for class B test fire, acyclic hydrocarbon (technical heptane) should be used. Extinguishing shall be commenced within 10 seconds after termination of free burning, lasting for full 60 seconds.

Test fire, group C
If test results of group B are positive, it is to assume that extinguisher is able to extinguish C class fire as well.





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