Fire Experiment in Standardized Safe Laboratory - Report Example

Fire experiment Name: Date: University Affiliation Fire experiment AIM To be able to show the relationship between the rate at which fire spreads in a given area in comparison with the temperatures to the given area. The second aim will be able to see the characteristics’ of the material as it is consumed in flames in the combustion box. The experiment will be done in a standardized safe laboratory. APPARATUS Firebox The dimensions s to be used as the fire box is of 65cm long 34 cm wide with a height of 38 cm. The box also has a roof with a wall that is 25 cm thick. It is also accompanied by a monolux layer of lining with a fire proof wall that has been constructed just after the fire glass. The compartment has a door with a height of 22.5 cm opening to up to 15 cm width. The floor hole has an axle that helps in providing passage to the fuel required for complete combustion process to take place. The floor is also specially made in such a way that it also acts as a weighing balance allowing the material to be recorded during the experiment. John(2000) Steel Wheels are provided to the firebox to give it more freedom when it comes to mobility and freedom. Thermocouples are distributed evenly in the compartment as they should be able to give precise and accurate readings of the temperatures which are a very important data set required in the experiment. Accurate data recording and interpretation requires to be done to ensure the final results are accurate reliable and valid. Hence the positioning of the thermocouples should be with high accuracy ensuring the same is acquired. Pauls (2002) Figure 1: illustration of the side view of the fire box Figure 2: illustration of the front view of the fire box Thermocouples In total there are a number of twelve thermocouples sued as the sensors in temperature recording in this experiment. The type of thermocouples used were of two combined, the first was the nickel – chromium and the second nickel – aluminium. Stainless steel material sheet is accompanied on the same. The thermocouples are positioned in such a way that they can be able to measure the temperature inside the chamber with one protruding outside the chamber in order to get the outside temperature. The positioning of the thermocouples is done in a form of three columns dimensions of 15 cm by 31.5 cm by 48 cm form the provided opening which is the connected to a data logger that manipulates the collected data taking the required temperatures of the fire compartment. Pauls (2002) Accuracy of the experiment The type of thermocouples used in the experiment had an accuracy error of 0.1 degrees Celsius. The high level of accuracy was to be used to get the most accurate results from the firebox as possible. To be able to determine the accuracy of the temperature readings being taken an inconel material was positioned inside the firebox during the experimental procedure. It allowed real time recording of data as it’s detected by the sensor helping to do away with experimental errors. The polymethyl methacrylate in the process of burning is broken down. It’s a very common material used in such combustion experiment where one piece is fully burnt during the experiment in one single run. Its thickness was 12 mm with dimensions of 10 cm by 10 cm by 20 cm by 20cm. the fuel tray is usually mounted to a weighing balance that will ensure there is real time determination of the weight of the material during the experiment. John(2000) EXPERIMENTAL PROCEDURE The PPMA material was first greased with gel petroleum and powder put on it to allow minimizing of the resistance to ignition. The following thing that was done was putting the plate of 10 cm by 10 cm on the ventilation area but 13 cm from the ventilation door. The pate is then mounted to a weighing balance that will allow taking of measurements. Fire was ignited with aid of a torch whereas at the same time temperature inside in the fire box was being recorded with help of the mounted squirrel data logger. The provided data logger extracted data from K type of thermocouples and the fire was allowed to burn until it went out by itself. The experimental procedure was repeated with only varying size of fuel being used of size 20 cm by 20 cm. Pauls (2002) Personal observation and timeline Incipient stage Time (s) Observation 0-15 The fire is ignited and burning begins 18 Smoke is produced from the fuel 38-144 The flame develops more orange color and crackling sound this shows the spreading rate of fire Growth stage 300-540 Further development of flame more smoke produced in the process Fully developed stage 670-1100 Flame is at its peaking covering most part of the ceiling at a fast rate more smoke produced as it can be seen coming out of the ventilation holes Decay stage 1860-2010 The flame burning ability declines alongside with the amount of smoke that has been generated 2600 The fire completely burns out by itself utilizing all available fuel. Figure 3: diagram showing the relation between temperature and time for the block of fuel Figure 4 :diagram showing the relation between temperature and time for smaller block of fuel Firebox temperature variation Six thermocouples are positioned below the bed of the fire box. They are meant to give the same range of temperature readings. However the first thermocouple will give the least temperature reading values because its position at the furthest point of the firebox. The ninth thermocouple had the second least temperature reading since its very close to the ventilation area. Some of the peak points of the temperature readings are given by the sixth thermocouple because it’s positioned right below the fire bed. The high temperature from the fourth thermocouple located on the top corner this implied that smoke was first dispersed to this region hence recording the high temperature values. Pauls (2002) The other group of thermocouples that had been placed at the top portion of the fire box also gave higher temperature readings this was a result of generation of a thermal layer of smoke in this region raising its temperatures. The two thermocouples that were very close to the source of heat the fire these were the seventh and eighth thermocouple showed the highest temperatures too from the experiment. The twelfth thermocouple which was placed near the vent also had high temperatures this was attributed to mass flowing of heated air around this region that resulted to rise in its temperatures. John (2000) When comparing the two masses of fuel the one with dimension of 20 cm by 2o cm generated more heat compared to the one with dimension of 10 cm by 10 cm this was because the larger fuel had more fuel to be combusted generated more heat hence thereby higher temperature recordings. Figure 5 : relationship of rate at which masses in two experiments are being experienced with time For the larger piece of mass the PMMA tends to reduce up to 350 seconds where it tends to be equal to that of size 10cm by 10 cm mass. The similarity was as a result of the fire ignition being at the first stage of combustion where in both cases little fuel was being consumed at the early stages of the fire. In this stage there is a lot of mass left UN burnt where as at the same time a lot of heat was being produced in both cases of the two mass of fuels. This stage shows that the fire is at its growth stage where. In all the two cases experiment one and experiment two both the is increased growth in mass being lost to the combustion. When there is high rate of mass loss then the stage can be related or defined as a fully developed fire. The. Last stage is that of decay of the fire where there is constant declining in the mass loses of the fuels used in both the two cases. The two graphs that have been plotted both shows that the rate at which mass is lost are proportional to the rate of heat that is being generated when the fuel is burnt. Pauls (2002) EVALUATION The experiment was able to identify the four main stages of fire development which include: the ignition stage, the developing fire stage, fully developed stage and the decay stage. During ignition there is low temperatures as a results of lower mass rate losses which continuously increase up to the fully developed stage of the fire beyond which the temperature drops as well as the mass loss rat during the decaying stage of the fire .from the two experiments the larger fuel has higher temperatures compared to the other but the other transitions do occur at the same transitional stages time. The 20cm by 20cm has considerably higher temperatures than the one of 10cm by 10 cm dimension this was due to the larger amount of fuel available for combustion as a result more mass loss rate consequently more heat generation that raises the temperatures. Pauls (2002) CONCLUSION At the end of the experiment we were able to identify and define all the four stages of fire development. The ignition stage, the developing fire stage, fully developed stage and the decay stage. We were able to also note that the rate of mass loss is proportional to the heat and temperature of the specimen under experimental observation. However one weakness in the experiment was that the flame didn’t move to the final flashing over due to inadequate fuel that is essential to take the flame to this stage. The rise of temperatures was only to the highest peak point beyond which it dropped for both cases this was as a result of the reduction of mass loss rate. The experiments were concluded as being successful experiments. Pauls (2002) REFERENCE 1. Fahy, R. & Proulx, G. (1997). ‘smoke and heat horizon evaluation’, Fire investigation Science: Proceedings of the Fifth International Symposium, Yuji Hasemi (ed.), World Congress Centre, Melbourne, Australia 713–24. 2. Horasan, M. & Bruck, D. (1994). ‘Investigation of causes of fire”, 4th International Symposium on Fire Safety and investigation Science Proceedings, ISFPA, Gaithersburg, MD, USA 715–26. 3. john letini (2000) “scientific investigation of fire investigation” second edition, ISFPA by pages 76-79 4. Pauls, J. (2002). ‘Evidence analysis , SFPE Handbook of Fire investigation, 2nd edn, National Fire Protection Association, Quincy, MA.,USA. 5. Proulx, G. (1995). ‘Evidence obtaining and evaluation in fire incidents buildings’, Fire Safety Journal, 24 (3), 229–46. Read More