Small Scale Compartment Fire - Lab Report Example

Lab experiment on small scale compartment fire Name Institution Subject Instructor Date Abstract The combustion that takes place of the hot gases and the flames may be ejected out of the building through the windows and the doors. The ejection of the flame may occur suddenly that may enhance the flame to rapidly flow to other compartments. Objects that are in the vicinity may be ignited leading to the spread of fire out of the building. In a scenario where the flame exhaust occurs through an opening, it takes place through ventilation that is controlled. This scenario is mostly associated with the flashovers and may pose as a health hazard to the facilities that are hydrocarbon. Ideally, the induction period which represents the time delay that occurs between the time of a given ignition and the exhaust of flame forms an important basis in ascertaining the characteristics of fire under the fire investigations. Analysis of the enclosed fire also aid in ascertaining the extent to which the fire would grow and the extent to which it would affect the buildings Introduction Ideally, fire that emanates from a compartment occurs in a closed space. They may arise as a result of fuel control where there is in-adequate air required to react with all the fuel in a given enclose. Additionally, it may arise due to ventilation limited due to limited air supply (Chandler, 2009).Various compartments exhibit different stages of fire such as the ignition stage, growth stage, flashover stage, fully developed stage as well as the decay stage. Early stage This stage, the compartment exhibits no effect on the development and the growth of fire. A layer would be formed under the ceiling as it flows out of the compartments. This results from the smoke and the hot gases (Lataille,2003). In the event that fire continues to grow while the openings are small to carry the products of combustion away faster or, at the same rate than they are being generated, the upper layer would increase and start descending towards the floor (Great Britain., 2006). The compartment would be fully involved in the scenario where fire has developed and flashover has been developed. Thereafter, the fire would decay till when all the fuel is consumed and it extinguishes itself. Aim This experiment aims at establishing how the fire from the compartments may develop from ignition to flashover as well as decay. Hypothesis There is a relationship between the time to ignition and size of opening. There is a relationship between the effect of temperature and time to ignition 2 Methodology This experiment utilizes a firebox and a thermocouple. The firebox represents a small compartment that has a dimension of (0.65m long by 0.34m wide by 0.38m high) It has the roofs and the walls having 0.025m external layer having monolux 500 while one of the wall is constructed from a fire resistant material glass. There was an adjustable door that is 225 high that opens between 0-0.15m wide. A hole was made on the floor so as to pass the axle that would support the fuel as well as enabling the weight of the material being recorded. It was placed so as to ensure that the centre locates itself as 0.45m. To ensure easy movements, the firebox was fixed in a steel frame that had the wheels that enhanced easy movement when needed. Three columns were placed in conjunction with the thermocouples that are located on the wall of the compartment. Thermocouple Measuring of temperature was done by connecting 13 thermocouples at a distance of 200mm into the firebox. They were composed of type K elements namely the nickel-chromium and nickel-Aluminum together with the sheet of stainless steel. One of the thermocouple is connected on the floor hole while the rest (12) were connected inside the compartment to measure the temperature of the inside air on the rear wall. Figure 1 views of thermocouple Materials Fuel (PMMA) They are used for burning that has dimension of 0.012m-0.25 that has dimensions of 100mm by100mm or 100mm by 100mm or 200mm by 200mm. They act as a suitable nanocomposite. PROCEDURE 1 The internal dimensions of the firebox were measured while the position of the samples throughout the test was located 2 The size of the ventilation was recorded 3 The thermocouples were cleaned on the inside of the firebox with a paper towel so as to ensure the readings are not affected by dirty or soot. 4 The thermocouples were then connected to the squirrel data logger that relates the record where the channel on the data logger. 5 The balance was switched on 6 The appropriate sample sizes tray was placed in the firebox 7 The button ``tare ‘’ was pressed on the balance 8 The sample was added to the tray while the PMMA powder was added over the fuel sample 9The initial mass of the fuel PMMA was recorded 10 The thermocouples were straightened to ensure that they were protruding into the firebox 11 The marked measuring stick was marked in the firebox so as to allow and observe the height of smoke at the time of intervals. This is placed at the front so as to ensure that 12 The squirrel data logger was started. 13 The sample was ignited using a lit paper while protecting oneself with the appropriate personal protective equipments. 14 the vent was adjusted to the required size 15 The event was adjusted to opening of the required size. 16 A small piece of paper was placed at the front of the box so as to ensure the signs of the flashover during the experiment 17 The mass of the sample was recorded together with the height of the smoke layer` after every minute 18 The observations were recorded. 19 The experiments were recorded after 15-20 minutes to ascertain whether the conditions were suitable The data logger was stopped when the test was complete. 4 Results Table 1 Full 1 Time Grams 30 569.0 60 568.5 90 566.0 120 567.0 150 567.1 180 569.0 210 563.6 240 563.0 270 563.5 300 563.2 330 564.0 360 562.5 390 561.2 420 561.1 450 563.8 480 562.4 510 561.4 540 559.0 570 558.6 600 558.6 630 558.7 Table 2 Full 2 time Grams 660 555.0 690 557.0 720 555.6 750 552.5 780 550.8 810 551.5 840 542.3 870 536.6 900 524.5 930 514.5 960 498.0 990 478.0 1020 465.4 1050 455.0 1080 431.0 1110 423.0 1140 404.0 1170 387.2 1100 360.4 1130 325 1160 301.8 1190 260 1210 255 Table 3 Full 3 1240 220 1270 121.5 1300 105 1330 102 1360 80 1390 60 1420 50 1450 10 1480 42 1510 3.6 1540 3.4 1570 3.2 Table 4 Full 4 time mass 150 556.5 180 555.4 210 553 240 544 270 532 300 511 330 481 360 447 390 409 420 382 450 355 480 355 297.5 355 Table 5 Half 2 630 360.2 660 342.2 690 324.5 720 304.4 750 286.2 780 270.0 810 254.0 840 221.4 870 208.0 900 192.1 930 174.8 960 157.8 990 139.8 1020 122.0 1050 104.4 1080 85.4 1110 70.1 1140 51.9 1170 34.8 1200 16.8 1230 2 1260 14.4 Table 6 Half 3 1290 30 1310 44.5 1340 57.9 1370 70.0 1400 80.0 1430 86.2 1460 90.8 1510 93.2 Table 7 Half 4 30 576.0 60 573.6 90 570.4 120 563.2 150 558.9 180 551.1 210 540.0 240 531.9 270 519.2 300 507.2 330 495.3 360 468.2 390 468.2 420 456.0 450 443.6 480 430.0 510 419.0 540 405.2 570 392.0 600 377.2 Table 8 Half 5 253.0 240.0 228.0 215.0 200.0 188.0 176.0 165.2 152.0 141.0 129.0 118.4 5 Discussions From the study there is a correlation that exists from the pool size with the time the flame of the exhaust in the opening 1 from the two heights. The time the flame takes time from the ignition from the fuel that is in the container The flame with high small compartment exhibited no flame exhausted. Containers that exhibited length of 100, 120, and 150 with 200mm had fire extinction as there was oscillation of the flames. 25 mm height has a flame exhibited in the 200mm container. This relates that the time required for exhaust is shorter as compared to the containers that had longer heights. Thaws illustrated by the nature of fire that exhibited at the initial stage. In the scenario where the fuel container, is heated the boiling point occurs due to the feedback of the radiation in which case the flame becomes more stable in the containers that are higher. This indicates that the feedback of the heat would be stronger. It was observed that, a flame which was exhaust and fast was observed in the container with higher container. Containers with low height had no flames exhibited at the openings The containers that had 50mm height containers exhibited high mass loss rate as compared to the ones with low heights. In the largest pool side that had 200mm by 200mm, the flames appear to be strong with the oscillations, with the instabilities being experienced when the heat and the mass loss rate were reduced making the flame to become extinct. Initially, the increase exhibited in the increase in the pool size made the loss of the mass rate to be increased. The pool size that had larger sizes that the exhibited value they had a reduced rate of mass loss. There was no correlation hat exhibit between the times that requires for exhaust as well as the size of the opening required for the pool fires. It is exhibited that the pool size would have an effect on the time taken from ignition to exhaust. Initially, as the pool increases the size of the pool the exhaust time also decreases. As time progress addition of pool size causes a decrease in the time taken to exhaust or the extinction of the given flame. Figure 2 Graph of mass flow rate against time Full 1 Figure 2 graph of mass flow rate vs. time Full 2 Figure 3 Graph of mass flow rate against time Full 3 Figure 4 Graph of mass flow rate against time Full 4 Figure 5 Graph of mass flow rate against time Half 2 Figure 6 Graph of mass flow rate against time Half 3 Figure 7 Graph of mass flow rate against time Half 4 Figure 8 Graph indicating relationship between temperature and time. 5.1 Analsyis From the results indicated from the loss of mass rate, there exists a correlation between the rate of mass loss rate and the time required to exhaust. There is an inverse relationship that indicates when the mass loss rate is higher the time to exhaust would be lower. Maximum flame occurred after 487 seconds whereas full ignition occurred after 450 seconds in full 1 The ventilation factors have also the effect on the time to exhaust. Apparently, increase in the results of ventilation factor also increases the time required to exhaust (Ubelaker, 2013). When a ma given maximum value is attained, further increase in the ventilation factor causes a decrease in the time to flame the exhaust. The small pool size indicates the time required to exhaust tends to be independent on the given distance. The scatter of data from the graph plotted indicates the differences obtained that exists between various time of exhaust that were measured. This was related to the size of the container, size of the opening and the position of a given container. Large pool size indicates that, the positions that are central exhibit exhaust that are first and the flame is delayed to exhaust when the pool was moved to and from the opening. The mass loss rate was high on the farthest distance between the opening and the pool. Initial stage After the ignition, the flame grows as the oxygen is readily available inside the box. This occurs after approximately 3-11 seconds after the ignition has taken place. Thereafter the fire results into a ventilation controlled in which the flame appears o be smaller and are less intense and mostly after 59 s. The liquid fuel that is in the pool becomes heated up from the flame after which it starts to boil after sometime. The mass loss rate increases as the shape of the flame further changes at approximately 137 seconds. The increase in the fuel flow rate from the container makes the flame to move towards the opening at approximately 160s and 170s. As the radiation feedback decrease, the rate of fuel flow also decreases making the flame to move back towards the container. This gives the start point of the oscillation of flames that may lead to the flame exhaust that occurs through the openings. The flame exhaust takes place periodically as fire that is inside the box leads to flaming that occurs in the openings. As the flame increases, pressure in the box increases as it blocks the inflow of fresh air from outside. This makes the fire to be less intense making the pressure to decrease thereafter. . This effect causes some fresh air inside the box making again fire to become stronger and increase in pressure once again. The heat feedback that exists from the flame towards the fuel that controls the rate of supply of fuel may also affect the oscillations. This lead to the total consumption of fuel that would lead to extinction of fire after approximately 1510s. An opening with 150mm exhibited a more table flame as compared to other sizes. This is because the supply of fuel was sufficient enough. This gives an indication that, the size of the opening greatly affects the behavior of flame in a given opening. Strong flame oscillations lead to quick and strong ejection of the flame outside the box towards a distance of approximately 0.6. Ejection of flame outside the box indicates that, the increase in pressure is higher in this box as compared to the rest of the boxes. The average velocity propagation of flame outside the box with a distance of 0 gives an indication that the flame has started the ejection taking place from the opening toward the inside of that box. These results would be useful in building and design as it would enable the engineers to design buildings that would be well ventilated that would ensure that incase of fire, smoke quickly gets out of the building. 6 Conclusion In a given pool size, the time delays tend to be similar. Additionally, it is evident that, n a given fuel bed, he time exhaust is less that leads to maximum possible value of the mass loss. When this pool is exceeded, a further increase in the time to exhaust leads to mass decrease in mass loss rate. Additionally, the height of the container would also affect the time that would require a flame to exhaust. The smaller pools exhibit independent exhaust with regards to the position of the pool size. A pool that was large he central position pool establishes the minimum exhaust. In case of a shorter distance, the long time taken to have flame exhaust was attributed by the airflow that was stronger near the openings. Air from outside the box pushes the flame into the box that caused a delay in the flame to occur at the opening. The results also indicate that, the behavior of a give pool of fire in a ventilated condition in a fixed box geometry regarding a variable source of fire as well as the opening settings. In future, further development should be conducted to establish the relations ship between these underlying parameters that would indicate the results in s real life scenario. References Chandler, R. K., 2009. Fire investigation. Australia, Delmar Cengage Learning. Great Britain., 2006. The Building Regulations 2000: fire safety: approved document B. Vol. 2, Buildings other than dwelling houses. London, TSO. Kleane, B. J., and Sanders, R. E., 2008. Structural firefighting: strategy and tactics. Sudbury, Mass, Jones and Bartlett Publishers. Lataille, J. I. ,2003. Fire protection engineering in building design. Amsterdam, Butterworth-Heinemann. Ubelaker, D. H., 2013. Forensic science current issues, future directions. Chichester, West Sussex, Wiley-Blackwell. Read More