The Ignitability Test - Report Example

Introduction When sample of materials are subjected to a variety of fire tests, it will be a way of determining whether the products can withstand the set stand which are usually set by building codes and other relevant legislation. In the process of planning and construction of buildings it is important to ensure that there is protection against fire hazards and also to assess the reaction to fire resistance and thus it is a requirement in both national and EC regulations. There are prescriptive fire models and their resulting fire test methods which are usually used to assess the reaction. The system of the reaction to fire in building products as illustrated in EN 13501-1:2007, requires the test of fires be done according to the new fire test methods, with emphasis being placed on the central test method, single burn item. The European reaction to fire classes are set according to the national classification system and the corresponding legal requirements, and thus clears products for use with consideration to national building regulations. Ignitability test EN ISO 11925-2:2010, involves the test specimen being placed to direct impingement of fire from a small flame. A specimen whose size will have a size of about 250mm by 90mm is attached in a vertical position to a specimen holder which has a U shape. Then the gas flame whose height is about 20mm is brought into contact with the specimen with the angle of contact being 45 degrees. For surface exposure the application point will be 40mm above the bottom edge while for edge exposure the application is at the centre of the width of the bottom edge. A filter is put under the specimen holder so as to enable monitoring the falling of flaming debris with the test apparatus being as shown in the figure 1. There are two flames application times and test durations which can be used putting into consideration the product class. For the case of class E products a 15s flame application is used with the termination of the test being effected 20 seconds after the flame being removed. On the other hand for materials in class B, C and D the flame application time is 30s with amaximum duration of 60s after removal of the flame. The test termination comes earlier in case there is no ignition being observed after the flame has been removed or if the flame stops burning (or if there is a glow) or in case the flame tip reaches the upper edge of the specimen. When classification based on the observation on whether the flame spreads reaching 150mm with a certain time and whether there is ignition of the filter paper resulting from flaming debris. Also there is observation of occurrence and duration of flaming in addition to glow observation. Test Apparatus The combustion chamber is the major apparatus to be used in the experiment. The chamber is an enclosure which is made of stainless steel and it has heat resistant glazed doors on both the front and the sides which are used to make observation. There is a horizontal plate with dimensions of 455mm by 210mm which is mounted on a metal grip mesh close to the chamber’s base. There are two guide rails which are fixed the plate and this makes it possible for the burner to be fixed at the desired position. The burner can be adjusted in a vertical position or it can be tilted into an angle of 45 degrees to its vertical axis. The burner is mounted on a plate which is placed horizontally and it be moved to and from in a horizontal position along the centreline of the chamber. This movement is done from outside the chamber and the distance is set in advance by the user through adjusting the external collar. The burner has a fine a fine adjustment valve fitting which enables accurate controls of flame heights to be achieved and also it has a propane regulator, flashback arrester and tubing. A specimen holder of standard size has the capability of clamming a specimen of 250mm by 90mm and it has a double flame which U is shaped which is constructed in stainless steel with a 15mm width and 5mm in thickness. The frame is in a hanging position from the support bar in a manner to enable the underside of the specimen to have a direct exposure to the flame along its centre line and edges. The specimen is prevented warping by ensuring that the two halves of the specimen holder are held together by use of bolts and wing nuts. The flame height adjustment can be effected by use of needle valves and gas supply regulator. The height of flame is done by use of a device which when placed against a fixed point of the burner a flame height of 20mm. Testing Operation The burner was lit in a vertical position and allowed to stabilize then the bulb burn was adjusted to give a flame height of 20mm. The door was then closed and the burner was tilted to an angle of 450 relative its axis and then it was moved in horizontal line up to the point the flame reached the pre-set contact point by use of a pusher rod. The stop watch was stated immediately when the flame got into contact with the specimen. The flame was applied to the specimen for 15 or 30 seconds before the burner being retracted in a smooth and continuous manner. Surface exposure For the case of surface exposure which applies for flat products, the application of the flame is at the centre line of the specimen at a point 40mm above the bottom edge with each different surface that may be exposed in practice being put to test. Edge exposure This is applicable for the case a flat single layer or multiple products with a total thickness being 3mm or more and the flame is applied at mid point at the point of the test specimen. Where the specimen is a flat single layer or for the case of multilayer products having total thickness of more than 3mm, the flame was applied to the centre of the width of the bottom edge of the test specimen a distance of 1.5mm behind the surface. For the case of multilayer products that are more than 10mm thick, there are additional tests were to be performed with the specimen being turned at 90 degrees about its axis and flame impinging at the bottom edge of the centerline of the underside for every layer. For the case where the flame application was 15s the total test duration was 20 s from the time of application of the flame. On the other hand for a flame application time of 30 seconds the test duration went up 60s from the time the flame was first applied. Results of experiment Surface test For the carpet and cushion with the flame being applied on the surface the following results was observed. For the carpet there were three types of material: horizontal and vertical lined both horizontal and the vertical. In this material no burn was experienced and the 150mm mark target was not reached. For the case of the cushion where two surface tests were performed there was also no burn and the 150mm mark was not reached. Edge test For the horizontal lined carpet there was burning and it took 30 seconds to reach the 150mm mark. For vertical lined carpets the 150mm line was reached in 5 seconds while for carpet with horizontal and vertical lines the 150mm mark was achieved in 10s. For the cushion the first specimen burning occurred with 150mm mark being reached in 17seconds while for the second specimen it took 16 seconds for the 150mm mark to be reached. Discussion The test which have just been shown in the results are useful in assessing classification according EN 13501-1. In this classification 6-10 single test are normally performed. The criteria used is dependant on the classification being aimed at. For the case of classification D-B, 30s exposure is a requirement with the flame height being expected to go beyond 150mm within a time of 60s after commencement of the test. For the case of classification E and En the time of exposure required is 15s with the flame height required not to exceed 150mm in 20s after the commencement of the test. The specimens are supposed to be an actual representative of the product for its end use application as far as possible. This is more so required for use in use of standard substrate which is clearly described in EN 13238. Product standards for specified materials (products) usually contain prescriptions regarding the construction of the specimens so as to achieve maximum field application, with sometimes guidance being given on test specimens for representation of a wider ranger of application. The commencement of testing is after the confirmation has been done in writing, with the test specimens having been conditioned as directed in the standard. Reference Efectis Nederland (2011). The ignitability test. Read More