Small Flame Experiment - Article Example

A) Small Flame Experiment The importance of this experiment is its ability to determine the ignitability of materials and whether certain materials have met the fire standards provided by national and EC regulations. The experiment involved the following apparatus to come up with the desired results: combustion chamber, ignition burner, specimen support arrangements, and two specimen holders. Test subjects are clamped to the specimen holder in the combustion chamber and are placed according to the area of interest. Specimen holders allow the samples to be suspended, tilted to some degrees, or can be laid flat which all depends on the type of exposure to be used for the experiment (surface exposure and edge exposure). Samples that melt or shrink away from the fire without igniting are held in the secondary specimen holder. Two small fires can be introduced to the sample depending on the type of materials used. For class E materials, small flames are introduced for 20 seconds and the test is terminated 20 seconds after the flame is removed. For classes B, C, and D, small flames are introduced for 30 seconds and the test is terminated 60 seconds after the flame is removed. Minimum number of specimens of building products should be six and the materials that are to be tested should be cut lengthwise and crosswise. Data gathered for analysis are the position of the applied flame, whether ignition occurs, and the height of the flame tip from the application point. Additional standards are required for samples that shrink away from the flame. (B) Lab Cone The importance of this experiment is its ability to identify the heat release rate of experimental fires as well as other important factors such as heat of combustion, ignition time, levels of carbon monoxide and carbon dioxide, and the amount of smoke present in the fire. The experiment uses a cone calorimeter system that allows experimentation, data gathering, and analysis to take place simultaneously. The system is equipped with measuring experimenting tools such as the load cell, spark igniter, cone heater, exhaust blower, and exhaust hood. It also involves measuring and calibration equipments like soot sample tube, oxygen analyzer, weighing device, and heat flux meter. Results of the experiment are collected and analyzed using the data collection and analysis system which needs to be calibrated before each experiment. All the initial data and information were entered in the data analysis system. Samples were tested for four different values of heat flux which are at 25kW/m2, 35kW/m2, 45kW/m2, and 55kW/m2. The duration of the experiment is very brief. When the test sample is placed in the appropriate holder, the ignition timer is initiated at the same time the spark plug is turned on. The time when the sample sustains flame is recorded and the spark plug is moved out from the flame. Cone calorimeter results as well as graphs for sample with filename greencarpet showed comprehensive analysis on the heat of combustion, ignition time, levels of carbon monoxide and carbon dioxide, heat release rate, and the amount of smoke present in the fire. (C) The Bang Box The importance of this experiments is the ability of the set up to identify the flammability characteristics of the given fuel mixtures. The equipments involved in this experiment are the bang box, fuel, tape measure, stopwatch, sound level meter, gloves, and goggles. The mechanism of the experiment is pretty straightforward. It involves the bang box which has to be turned on before the fuel mixture is introduced in the system. Fuel mixture is introduced via a dropper. Air is introduced as well through a fan that is run for approximately 5 seconds. Once the air/fuel mixture is completed, an ignition source is introduced in the system which may cause explosions of varying degree depending on the strength of the fuel mixture. If ignition occurs, two factors need to be determined -the distance traveled by the explosion and the height of the observed explosion. Other observables include the severity of the explosion determined from the color of the flame produced, the loudness of the explosion, and the height of the projected cylinder lid. Results are tabulated for analysis. (D) Fire Box The importance of this experiment is it is able to simulate the results of fires occurring in small compartments. A fire box of dimension 0.56m long by 0.3m wide by 0.3m high is constructed from ‘monolux 500’ lining with one wall constructed from fire resistant glass for observation. The fire box is fitted with four thermocouples on three columns or a total of 12 thermocouples. These thermocouples will measure the temperature inside the fire box when fire occurs. There are two types of fuel for this experimental set up. PMMA fuel is used to ignite and propagate flame on the fuel. The fuel is placed on one location and it will be reached by the ignition through the PMMA fuel spread throughout the fuel slab. The box is then ignited using a PMMA fuel and the resulting fire is observed. Data and analysis are acquired from squirrel data logger. The experiment has four variations which are full-size opening cold compartment, full-size opening warm compartment, half-size opening cold compartment, and half-size opening warm compartment. This experiment gathers the mass of the sample and the height of the smoke layer on periodic intervals (usually every 60 seconds). The opening of the vent is adjusted to give the required size of the fire box. The smoke extract system is switched on before the fuel is ignited. Data collection through squirrel logger is halted when the fire ceases. (E) Effects of Fuel Mixture The importance of this experiment is its ability to measure the minimum amount of oxygen required by a particular material to sustain combustion or the limiting oxygen index at the same time it demonstrates the efficiency of combustion. Test samples were cut according to their specifications. For example, type I materials are typically cut thinner than type II materials in order to sustain combustion. There are two manners to test the samples for this experiment. One is the top surface ignition which measures the lowest amount of fuel mixture that the surface of the material can handle to sustain ignition and the other one is the typical method which measure the overall minimum amount of fuel required to sustain combustion of the material. All samples are to be tested in an apparatus set at a certain ambient temperature and on a specific nitrogen gas mixture. Once the results are gathered, calculating the oxygen index using the equation OI = c + kd is used. The burning behavior of the materials involved is measured at specific intervals during which both oxygen and nitrogen levels are varied. Materials of different types typically give off different results as per the required fuel mixture for continuous combustion. (F) Fires in Inclined Trenches A fire burning in open space will entrain air from all sides which creats an imbalanced in the air flow. The imbalance restricts air entrainment and the pyrolysing produces travel high up in the plume before complete combustion and heat release. This phenomenon is called as trench effect and is known to occur on fires adjacent to inclined surfaces. The importance of this experiment is its ability to explain how trench effect occurs and what can be done to minimize the possible resulting damage of the fire. The experiment is approached pretty much straightforward. A test trench of definite length and dimension is constructed from Monolux board while the other side is constructed using Georgian wired glass. The angle of inclination of the test trench is designed to be varied. Fire is introduced in the bottom of the test trench and the progress of the flame is measured. Variations of the inclination of the trench typically start at 30 degrees and lowered until the trench effect is no longer observable. There are four observables for this experiment which are the height of the roof, the angle of the trench, the time it took the flame to spread over a predetermined distance, and the angle of the flame front and the height of the flame. Results show that the steeper the trench, the faster the flame front reaches the topmost part of the trench. Read More