modeling of a portable water based fire extinguisher

Mechanical Engineering Department

Graduation Project (2):

“Modelling of a portable

Water based fire extinguisher”

Ragheb Hasan Al-Nammari Thaer Mousa

20122025047 20112025025

Under the supervision of:

Dr. Mohammad K. Alkam

2016-05-10

Content pageList of tables and figures .......................................................... 3

Nomenclature .................................................................... 5

Abstract .............................................................................. 7

Chapter 1, Introduction .................................................... 8

Classification of Fires ........................................................ 9

Classification of portable fire extinguishers .................... 10

Statistics ............................................................................... 11

History .................................................................................. 13

Chapter 2, Modelling ........................................................... 14

Chapter 3, Discussion ..............................,.......................... 17

Chapter 4, Conclusion ......................................................... 45

Reference ............................................................................. 46

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List of tables and figures:

Table-1 types of extinguishers around the world 7

Table-2 types of extinguishers in the US 8

Table-3 types of extinguishers in the UK 8

Table-4 types of extinguishers in Australia 8

Figure-1 the inside of a portable fire extinguisher 9

Figure-2 fire in the US during 2014 11

Figure-3 fire incidents by the type in the US 12

Figure-4 fire incidents in the US 12

Figrue-5 cost of fires in the US 12

Figure-6 Fire incidents in England 12

Figures from 1.1 to 13.4b parametric figures (21-44)

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NomenclatureA -Inner Area of the Cylinder (m2)

Q¿ -heat transfer to inside cylinder (W)

Qout -heat transfer to outside cylinder (W)

W ¿-Work done on the system (W)

W out -Work done by the system

ma -Mass of air (kg)

cva -specific heat at constant volume ( kJ

kg∗k)

Po-Atmospheric pressure (kpa)

ΔT -Temperature difference (K or ℃)

ΔV -Volume difference (m3)

h¿-Convection heat transfer coefficient ( W

m2∗K )

t -time of discharge liquid ( s )

R -Gas constant ( kJ

mol∗K )

NuL -Nusselt number

k -Thermal conductivity ( W

m∗K )

Pr -Prandtl number

α -Thermal diffusivity ( m2

s )

υ -Kinematic viscosity ( m2

s )

Ra -Rayleigh number

Ta -Temperature of air ( K )

L -Length of the air ( m )

a -Area of the inside tube (m2 )

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Va -Volume of air (m3 )

g -Gravity ( ms2 )

m -Mass ( kg )

v -Velocity ( ms )

ρ -Density ( kgm3 )

mo -Mass flow rate of the liquid ( kgs )

U -Internal Energy ( kJ )

z -Altitude of the system ( m )

H ¿ -Enthalpy of fluid entering ( kJ )

H out -Enthalpy of fluid exiting ( kJ )

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Abstract

A fire extinguisher was developed throughout the past years for a better performance. It went through many developments. There are many factors that affect the performance of a fire extinguisher. In this paper we briefly discussed the evolution of fire extinguishers. We briefly explained the types of fire extinguishers and classes of fires they are used to extinguish. Statistics about the fire accidents that happened in the United States and England are also shown.

The design of an actual portable fire extinguisher requires an orifice such that the air gets mixed with the water flowing out. We included this orifice in our calculations. The effect of this orifice is determined and the air mass flow rate is calculated.

Finally, we performed a parametric study calculating the change in pressure, temperature, water mass flow rate, air mass flow rate, mass of water and volume of pressurized air with time. The changes in the aforementioned properties are illustrated in multiple figures.

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Chapter 1

Introduction

Fires are common accidents that happen in every country in this world. Humans through past years have developed the concept of a fire extinguisher to fight fire accidents. The concept of a fire extinguisher has gone through a lot of development from being a “water bomb” to the conventional cylinder we know and use nowadays.

Fire extinguishers are used widely in the world in fighting relatively small fires due to their ease of use and availability. They can save lives in case of small and contained fires. They have become an essential requirement in every facility and every car and every house. Using fire extinguishers will reduce injuries or deaths. It is preferable to have two or more types of fire extinguishers in a facility for different types of fires (as will be discussed later).

The initial pressure, temperature and volume of water are important for knowing the discharge time and capacity of a cylinder. Different initial pressures will discharge water in different mass flow rates. Different temperature will also affect the discharge time

Fire extinguishers come in different sizes and shapes. Some are hand-held, some are cart-mounted and some are carried on the back. The Handheld ones weigh in the range of [3-14] kgs. The Cart-Mounted weighs more than 23 kgs and is used in construction sites, airport runways, etc. The most common extinguisher is the CO2 based fire extinguisher. The reason why it is so commonly use is because its ability to fight liquid and electrical fires which are the most common types of fires. The problem with it is that it’s expensive. The water based fire extinguishers, however, are cheaper but they only fight fires caused by ordinary combustibles. It’s also commonly used because there are a lot of ordinary combustibles that exist in all places.

An interesting phenomenon we would like to briefly discuss is the “flare-up” phenomena. It happens instantly during fire fighting when water mist touches the flames of the fire. What happens is an instant increase in the heat emitted and size of the fire; it cools down a bit right after the flare-up. Generally, not all types of fires need the same amount of time to be extinguished. It all depends on the type of fuel, type of method used to extinguish the fire, compartment geometry and the type of mist used. In all cases, water mist must be supplied until making sure the fire is completely extinguished. Stopping supplying water earlier may “bring the fire back to life”. The main components of the water-based Fire Extinguisher assimilate in hand-held cylinder that has a chamber filled with compressed air while the rest of the cylinder is filled with liquid water with a long tube inside the water and connected to the jet. A handle and a pressure gauge are supplied.

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Source of Fires and how to avoid them:

A fire can be caused by many reasons; small fires are mostly caused by human mistakes. Fires might be cause due to lack of safety considerations or due to carelessness in storing some combustible materials or allowing flames in a place that is saturated with combustible vapours and gases. Sometimes, overloading of some electrical devices or not cooling them while using them, neglecting their maintenance increases the hazards as well.

We have to avoid fires by making sure to avoid the causes of fires. For example we can maintain the cleanliness and good ventilation to get rid of combustible volatile gases. As for the critical electric devices, operating them under the allowable load and NOT overloading them under any circumstances increases the safety while operating. Also performing periodic check-ups on electrical devices is crucial as well. The facility must also be provided with fire extinguishers in case a fire happened.

Classification of Fires:

Fires are classified according to their causes. Fire extinguishers are also classified according to the types of fires they are used to extinguish. The classification of fires may vary from country to another. Fires are classified into five categories. According to American and Australian standards, electrical fires are classified in a class of their own while according to European and Asian standards, they are unclassified. The following table shows these classifications.

American European UK Australian/Asian Heat resourceClass A Class A Class A Class A Ordinary

combustibles

Class BClass B Class B Class B Flammable

LiquidClass C Class C Class C Flammable Gas

Class C Unclassified Unclassified Class E Electrical equipment

Class D Class D Class D Class D Combustible metal

Class K Class F Class F Class F Cooking oil or

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fatsClassification of portable fire extinguishers

Portable Fire extinguishers are manufactured for the suppression of multiple types of fires. Each type of fire extinguisher has its own colored label on it marking which type of fire it fights. Each type has its drawbacks as well as its advantages. Classifications are as follows: USA: [4]

UK and Europe: [5]

Australia: [6]

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Statistics:

During the past year (2014) in the USA, great number of fire incidents happened causing deaths and losses. Fire extinguishers are created to help reduce the huge numbers of losses and injuries. The following statistics were taken from the latest report of the NFPA that was published in September, 2015. According to the NFPA, an estimate of 1,298,000 fires occurred in the USA in the year 2014. An estimate of 494,000 was structure fires, 167,500 were highway vehicle fires, 610,500 outside and other fires. 3,275 civilian death were recorded, 15775 injuries and an 11.6$ Billion were lost due to property damage. There was a considerable increasing percentage estimated at 4.7% from year 2013. From the 3,275 deaths, 2,745 happened in the home! Another 310 civilians died in highway vehicle fires. As for injuries, rough estimates of 15,775 civilians were injured in fires other than those who were injured but didn’t report the injury. Of these, 13,425 civilian injuries occurred in structure

fires. 11,825 injuries were at home. 1,275 injuries occurred in highway vehicle fires. When it comes to Property Damage, a loss of around 11.6$ billion was recorded in year 21014. $9.8 billion of property damage occurred in structure fires, including $6.8 billion in property loss in home fires. Highway vehicle fires resulted in $1.1 billion in property loss last year. With the spread awareness of the importance of the presence of fire extinguishers in every facility in the country and the continuous improvements in fire extinguishers and classifying the fires and their appropriate type of fire extinguisher that has to be used in that case, the number of fires, deaths and losses has decreased significantly in the past 20 years. In England, the annual report of the Local authority fire and rescue services of the English government issued for the period from April, 2014 to March, 2015 discussing numbers of deaths and their decreasing rate. Around 495,400 incidents in England during 2014-15 were reported. The following figure shows a 6% decrease compared to the previous year and a decrease of 42% compared to ten years ago. Of these incidents, around 154,700 (31% of incidents, which is 2% less than previous year) were fires during 2014-15. From the figure, a 10% depression than previous year is noticeable. Around 125,000 (25%) were non-fire incidents. This figure shows a 5% decrease compared to the previous year. Local authority of fire and rescue services attended around 215,600 (44%, which is 1% greater than last year) fire false alarms. This figure shows a 4% decrease compared to the previous year.[7][8]

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History of fire extinguishers:

From early ages, people have depended of buckets and hand pumps to pump water to extinguish fires, they used to stand in line from water source to the fire and transfer the buckets from one to another. Later, the principle of a fire extinguisher that automatically extinguishes fire was patented by Ambrose Godfrey. His extinguisher was a kind of an extinguishing bomb that contained the extinguishing agent. Gunpowder was contained in a chamber and a fuse from it to the atmosphere benefiting from the fire to explode the “bomb”.

George Manby was the one who invented the current fire extinguisher in its current shape. The shape and anatomy of the cylinder didn’t change through years as much as the change that happened in the extinguishing chemical solutions contained in it. Scientists first started with Potassium Carbonate but banned it later due to its toxicity. After that, the idea of compressing the extinguishing agent appeared to give higher propelled mass flow rate. Scientists made sure to use environment friendly extinguishing agents. They came down to using CO2 and dry powder because they extinguish many kinds of fires, especially electrical ones. Water is also used later for the type of fires which its fuel is wood or plastics, water is preferred for these fires because it is cheap and effective.

The scientist made some experimental on the portable water fire extinguisher and said the standard of the portable fire extinguisher must be have water with volume 9.5L (2.5 gallon) and the portable fire extinguisher weight 13.6 kg (30Ib) and then expel water through the nozzle with range 10.7m to 12.2m ( 35 to 40 ft ) and the portable water fire extinguisher must be kept away from area that it conditions below 0℃ (32℉).

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Chapter 2

Modeling

Our main purpose in this paper is to perform modelling and analysis to a water based fire extinguisher. We have calculated and analyzed the change in pressure, temperature and volume of water with time for different mass flow rates. We included the effect of heat transfer. An orifice is present in the walls of the air chamber that allows air to flow out of the chamber and mixing with the water coming out making sprayed water. The drop of the air pressure affects the exit mass flow rate by the experimental equation (All characteristics and heat relations are taken from the heat transfer book cited in the references):

(1) Q=K∗Pn ; where P is the gage pressure at nozzle inlet [16]

K=1.2525× 10−6 m3/Pa0.44

n=0.44

The previous results of K and n are based on practical experiments. [17]

Our base case will be:

P|,|1=8atm=810.6 kPa , T 1=298 K , dorifice=0.001 m , Dcylinder=0.2m

P|,|1=7atm=709.275 kPa , Lcylinder=0.55m , d tube=0.02 m , ∀air=0.0123m

hair=0.39 m , mair=0.1166 kg , ∀total=π4∗(0.2)2∗0.55=0.0173 m3

With air properties as follows at 303 K

C v=0.718 kjkg . K

, ν=15.89× 106 m2

s, Pr=α /να=22.5 ×10−6 m2

s, k=26.3× 10−3 W

m . K

Using the maximum choked flow equation:

(2) ˙me ,a=

0.04042∗( π4∗0.0012)∗810600

√298=1.4907 ×10−3 kg/s

˙me ,w=1000∗K∗Pn=1.2525 ×10−3∗[709275− (9810∗0.39 )]0.44=0.4689 kg/ s

To calculate the change in the volume of air, thus the mass of air, we can relate it to the change in volume of water. The decrease in the volume of water must be equal to the increase in the volume of the air.

(3) m2 ,w=m1 , w−me ,w∗t=5−0.4689∗1=4.5311kg

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This yields the change in water volume:

(4) ∆ ∀w=0.4689 ×10−3 m3/s

The mass of air is:

(5) m2 ,a=m1, a−me ,a∗t=0.1166−1.4907 ×10−3∗1=0.1151kg

The volume of air increased by the same amount the water volume decreased:

(6) ∀2=∀1+0.4689 ×10−3=0.0128 m3→ hair, new=0.4074 m

For heat calculation, we need to find Nusselt and Rayleigh numbers first to find h(x) and from it we can get the rate of heat transfer from the ambient air to the cylinder. It should be mentioned that we neglected radiation because of the relatively far “safe distance” from the fire. We also combined the effect of convection from all sides of the cylinder and convection from the water surface to the air in one h(x).

(7) Rax=gβ (|T s−T ∞|) . x3

ν .α; β= 1

T f;T f=

T air+T∞

2=298+303

2=300.5 K

Rax=

9.81300.5

(303−298 )∗0.393

15.89∗22.5∗10−12 =27082075.2900

(8) Nux=0.68+

0.67 Ra x1/4

[1+( 0.492Pr )

916 ]

49

=h ( x ) . x

k

Nux=0.68+

0.67 (27082075.29)1/4

[1+( 0.49222.5/15.89 )

916 ]

49

=h ( x )∗0.3926.3× 10−3 →h=2.7270

W/m2 . K

And from Newton cooling law we can calculate the rate of heat transfer. We shall assume constant heat transfer along the height of the cylinder.

(9)

Q ( t )=[h ( x ) . A side surface . (T s−T ∞ ) ]+[h ( x ) . Awater surface . (T w−T ∞ ) ]=[h ( x ) . (0.2 π . x ) . (T s−T∞ ) ]+[h ( x ) . ( π (0.2)2

4) . (T w−T ∞ ) ]

Q ( t )=[2.727 . ( 0.2 π∗0.39 ) . (303−298 ) ]+[2.727∗( π (0.2 )2

4 )∗(298−298 )]=3.3412W

Now since we calculated the heat transfer, we will use the first law of thermodynamics to calculate the change in temperature of the compressed air.

(10) Q−Patm (∀2−∀1 )− ˙me, a∗ha=m2 ,a u2−m1 , au1

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3.3412−101325 (0.4689 ×10−3 )−(1.4907 × 10−3∗1005∗298 )=(0.1151∗718∗T2 )−(0.116∗718∗298)

T 2=295.9469 K

And from the ideal gas law we calculate the change in Pressure:

(11) P=m∗R∗T∀

P2=m2∗R∗T2

∀2=0.1151∗0.287∗295.9469

0.0128=763.7673 kPa

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Chapter 3

Discussion

A condition that 90% of the water in the extinguisher must leave the container was considered when performing the parametric study starting from the base case mentioned earlier.

In figure1.1 and 1.2 and 1.3 based on initial temperature of air at 25℃ of air and initial pressure 8 bar of air and initial volume of air is 0.0123m3and without heat transfer and orifice diameter. We see that the mass flow rate of water has great effect on the pressure and temperature of the air and discharge time. The drop in temperature with different mass flow rates happens in a longer period of time. They don’t necessarily drop to the final temperature in all cases. With higher mass flow rates, the expansion of air is faster thus the drop in temperature is greater. The mass of water, however, as expected drops faster with higher mass flow rates. The pressure doesn’t drop linearly. But it drops to the same value in all cases.

In figure 2.1 and 2.2 and 2.3 based on mass flow rate of water is 0.5 kgs (assume is

constant) and initial temperature of air is 25℃ of air and initial pressure of air is 8 bar of air and without heat transfer and orifice diameter. We see that the volume of air has effects on the discharge time and has effects but not great effects on the pressure and temperature of air.

In figure 3.1 and 3.2 and 3.3 based on initial temperature of air at 25℃ and mass flow

rate of water is 0.5kgs (assume is constant) and initial volume of air is 0.0123m3 with no

heat transfer and orifice diameter. We see that the initial pressure has no effect on discharge time but has effects but not great on the temperature of air. The greater expansion of air gives greater temperature drop. However, higher initial pressure restricts the expansion of air, thus reducing the temperature drop. The pressure drop is the same, so higher initial pressure yields higher final pressure. The interesting case here is that that the change of water mass with time doesn’t get affected by the initial pressure, because simply that has only to do with the output mass flow rate of water, this is also the case for different initial temperatures of air. The temperature drops linearly with time.

In figure 4.1 and 4.2a and figure 4.2b and 4.3 based on initial pressure 8 bar of air and

mass flow rate of water is 0.5kgs (assume is constant) and initial volume of air is 0.0123

m3 with no heat transfer and orifice diameter. We see that the initial temperature has no effects on the discharge time but it effects on the pressure of air, It is almost non-existent. A higher initial temperature yields higher final temperature because the rate of change in temperature is the same in all cases. The pressure drop may look the same with different

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initial temperature but in fact its change is very small that it’s not noticeable. And here’s a figure showing the very small difference.

All figures mentioned previous, The discharged water is 100% of initial mass of water and specified for each discharge time.

In figure 5.1 based on the initial temperature of air 25℃ and initial pressure 8 bar of air

and mass flow rate of water is 0.5kgs (assume is constant) and initial volume of air is

0.0123m3. We see that the difference between the two curves is neglected so we can assume heat transfer approximately has no effects on the temperature but in certain range, because we will see in below figures that the heat transfer has great effects in temperature. It is noticeable that the change in temperature and mass of water with time is decreasing linearly, unlike the pressure. In our calculations, when we calculated the heat transfer convection coefficient of the ambient air we assumed constant properties of the air at T=300K, arguing that the properties will not change significantly because the specific heat of air at 300K is 0.718 kJ/kg.K and at 250K is equal to 0.716 kJ/kg.K and at 350K is 0.7211 kJ/kg.K. with an negligible error of 0.2785% and 0.432% respectively. The surrounding temperature will never reach -23℃ and it is unlikely for it to reach 77℃ either. Taking into considerations the changes in other properties, and calculating Rayleigh and Nusselt numbers at temperatures of 250K and 350K will give us values of h(x) of 2.67 and 2.43 respectively. Comparing these values with the value of (h) at 300K will give us an error of 4.7% for both cases, which is acceptable. The effect of heat transfer to the cylinder is small. We chose to show it with multiple assumptions. However, we provided 2 curves above comparing the change in temperature with and without heat transfer; we can see the difference is almost a degree or two.

In figure 6.1 based on initial temperature 25℃ of air and initial pressure for air 8 of air bar and initial volume of air 12.3L(liter). We see the effects of heat transfer and orifice diameter on the behavior of temperature and pressure of air. The orifice diameter=1mm has great effects on properties of air than the heat transfer in range of discharge time.

In figure 7.1a and 7.1b and 7.2a and 7.2b and 7.3a and 7.3b based on initial temperature 25℃ of air and initial pressure for air 8 of air bar and initial volume of air 12.3L(liter) with heat transfer and orifice diameter = 1mm. As decreasing in the steps the behavior of properties will approach to the actual behavior. Also there are great difference in the behavior of curves of properties of air for time steps =1s and time steps =0.1s, but we can neglect the difference in the behavior of curves of properties of air for time steps =0.1s and time steps =0.01s because the difference is very small. Also we notice that as we take time step=0.1s, the temperature will not decrease linearly like the temperature will decrease linear at time step =1s.

In figure 8.1 and 8.2 and 8.3 based on initial temperature 25℃ and initial pressure 8 bar and initial volume 12.3L with heat transfer and orifice diameter =1mm in non-isentropic process.. We see that there difference between the behavior of temperature of air in isentropic process and non-isentropic process. The difference is caused because there are conditions of isentropic process which assimilate in :1) No temperature difference

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2) No pressure difference 3) No heat transfer 4) No friction 5) No combustion

Also the turbulence of water will cause the irreversibility process.

In figure 9.1 and 9.2 and 9.3 and 9.4 based on initial temperature 25℃ and initial pressure 8 bar and initial volume of air 12.3L with heat transfer and orifice diameter=1mm. We see the Initial temperature does not affect on the discharge time and on pressure behavior and on mass flow rate discharged of water. For reminding the mass flow rate of water is function of inside pressure and height of air inside the cylinder. For approximately t=11s, the 90% of initial water will discharge.

In figure 10.1 and 10.2 and 10.3 and 10.4 based on initial temperature 25℃ and initial volume of air 12.3L with heat transfer and orifice diameter=1mm. We see the pressure has effects on discharge time and mass flow rate discharge of water and little effects on mass of water but we can assume there is no effects on temperature behavior. Also these figure show the different properties in range of time and shows how the initial pressure affects on the time discharge.

In figure 11.1 and 11.2 and 11.3 and 11.4 based on initial temperature 25℃ of air and initial volume of air 12.3L and initial pressure of air 8 bar with heat transfer and orifice diameter. We see that the orifice diameter has great effects on the discharge time and mass flow rate discharge and mass of water and temperature and pressure of air. First , the orifice diameter has huge effects on the temperature of air but at orifice diameter =3mm and approximately t =13.8s, it has not great effects to decrease the temperature of air and the increasing in temperature caused by heat transfer from outside and from water that assumed the temperature of it remain constant and equal to 25℃, here the heat transfer has great effect on the air. We note that when we use he orifice diameter , the mass of water will not discharge 90% of initial mass of water due to the mass flow rate=0 because it depend on the gage pressure of air and height of air.

In figure 12.1 and 12.2 and 12.3 and 12.4 based on initial temperature of air 25℃ of air and initial pressure of air 8 bar with heat transfer and orifice diameter=1mm. We see that the initial volume of air has effects on the discharge time and behavior of the properties of air and water. This effects appear clearly in temperature than pressure of air.

In figure 13.1 and 13.2 and 13.3 and 13.4a and 13.4b shows the effects of the types of nozzle and orifice diameter and initial volume of air and initial temperature of air on the total discharged time for several initial pressure of air. For figure 13.1 based on initial temperature of air 25 and initial volume of air 12.3L and with heat transfer and orifice diameter =1mm, It shows the effect of type of nozzle on the total discharge time of water (90% of water out) for several initial pressure, we can consider that the effect of Spiral nozzle is same as the Wide angle full cone nozzle that have same effect on total discharge time but the full cone nozzle have great effect on total discharge time for water, it increases the discharging process than the Spiral nozzle and Wide angle full cone nozzle. In figure 13.2 based on initial temperature of air 25 and initial volume of air 12.3L and

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with heat transfer and orifice diameter, it shows the effects of orifice diameter on the total discharge time for several initial pressure, the effects all orifice diameter except orifice diameter 3mm are approximately convergent and differentiate reason for orifice diameter =3mm ,it decrease the pressure of air quickly and that decrease discharging process for water. In figure 13.3 based on initial temperature of air 25 and with heat transfer and orifice diameter=1mm.We see that the initial volume of air has effect on the total discharge time for water but this effect is not great. We notice that at certain initial pressure, the difference between the curves are equal for example at initial pressure 10 bar we see that the total discharge time for water at 8.3L of air is 10s and for 9.3L is 12s and for 10.3L is 14s and for 11.3L is 16s and for 12.3L is 18s. Finally in figure 13.4 based on initial volume of air is 12.3L and with heat transfer and orifice diameter =1mm. We see that the initial temperature of air has no great effect on the total discharge time for water for several initial pressure of air so we can neglect this effect and say that the initial temperature has no effect on the total discharge time for certain initial pressure.

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Figure 1.1 Variation of Mass of Water with Time for several mass flow rate of water

Figure 1.2 Variation of Pressure of Air with Time for several mass flow rate of water

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Figure 1.3 Variation of Pressure of Air with Time for several mass flow rate of water

Figure 2.1 Variation of Pressure of Air with Time for several Initial Volume of Air

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Figure 2.2 Variation of Mass of Water with Time for several Initial Volume of Air

Figure 2.3 Variation of Temperature of Air with Time for several Initial Volume of Air

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Figure 3.1 Variation of Temperature of Air with Time for several Initial Pressure of Air

Figure 3.2 Variation of Pressure of Air with Time for several Initial Pressure of Air

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Figure 3.3 Variation of Mass of Water with Time for several Initial Pressure of Air

Figure 4.1 Variation of Temperature of Air with Time for several Initial Temperature of Air

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Figure 4.2a Variation of Pressure of Air with Time for several Initial Temperature of Air

Figure 4.2b Variation of Pressure of Air with Time for several Initial Temperature of Air

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Figure 4.3 Variation of Mass of Water with Time for several Initial Temperature of Air

Figure 5.1 Variation of Temperature of Air with Time either with heat transfer and without heat transfer

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Figure 6.1 Variation of Pressure of Air with Time either with heat transfer and orifice diameter and without heat transfer and orifice diameter

Figure 6.2 Variation of Temperature of Air with Time either with heat transfer and orifice diameter and without heat transfer and orifice diameter

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Figure 6.3 Variation of mass flow rate of water with Time either with heat transfer and orifice diameter and without heat transfer and orifice diameter

Figure 7.1a Variation of Temperature of Air with Time for several steps

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Figure 7.1b Variation of Temperature of Air with Time for several steps

Figure 7.2a Variation of Pressure of Air with Time for several steps

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Figure 7.2b Variation of Pressure of Air with Time for several steps

Figure 7.3a Variation of mass flow rate of water with Time for several steps

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Figure 7.3b Variation of mass flow rate of water with Time for several steps

Figure 8.1 Variation of Temperature of Air with Time for Non-Isentropic Process and Isentropic Process

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Figure 8.2 Variation of Pressure of Air with Time for Non-Isentropic Process

Figure 8.3 Variation of Mass Flow Rate of Water with Time for Non-Isentropic Process

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Figure 9.1 Variation of Temperature of Air with Time for several Initial Temperature of Air

Figure 9.2 Variation of Pressure of Air with Time for several Initial Temperature of Air

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Figure 9.3 Variation of mass for rate of water with Time for several Initial Temperature of Air

Figure 9.4 Variation of mass of water with Time for several Initial Temperature of Air

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Figure 10.1 Variation of Temperature with Time for several Initial Pressure of Air

Figure 10.2 Variation of Pressure with Time for several Initial Pressure of Air

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Figure 10.3 Variation of mass for rate of water with Time for several Initial Pressure of Air

Figure 10.4 Variation of mass of water with time for several Initial pressure of air

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Figure 11.1 Variation of Temperature with Time for several Orifice Diameter

Figure 11.2 Variation of Pressure with Time for several Orifice Diameter

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Figure 11.3 Variation of mass flow rate of water with Time for several Orifice Diameter

Figure 11.4 Variation of mass of water with time for several Orifice Diameter

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Figure 12.1 Variation of Temperature with Time for several Initial Volume of Air

Figure 12.2 Variation of Pressure with Time for several Initial Volume of Air

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Figure 12.3 Variation of mass flow rate of water with Time for several Initial Volume of Air

Figure 12.4 Variation of mass of water with time for several Initial volume of air

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Figure 13.1 Variation of Total time for discharge water with Initial Pressure for several type of nozzle

Figure 13.2 Variation of Total time for discharge water with Initial Pressure for several Orifice Diameter

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Figure 13.3 Variation of Total time for discharge water with Initial Pressure for several Initial volume of air

Figure 13.4a Variation of Total time for discharge water with Initial Pressure for several Initial Temperature of air

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Figure 13.4b Variation of Total time for discharge water with Initial Pressure for several Initial Temperature of air

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Chapter 4

Conclusion:

The principle of a fire extinguisher started many years ago. A lot of developments have been done to cylinder itself and more developments have been done to the extinguishing agents. Scientists throughout the years tried and are still trying to use environment friendly and non-toxic agents.

Fire extinguishers come in many types. Each type is for certain kinds of fires. Using an extinguisher to the wrong kind of fire may cause serious hazards. The classification of extinguishers differs from country to country but they have few classifications in common.

The use of fire extinguishers in facilities and the knowledge of how to use them helped in reducing losses and deaths caused by fires. Water based fire extinguishers are used for fires that have a fuel of wood, plastics or any daily used material that does not react with water. This type shall not be used with electricity, obviously! It also shall not be used with combustible metals, flammable liquids or gases or cooking oils.

A lot of parameters affect the performance of a fire extinguisher such as temperature, pressure, the mass of water in the cylinder, the water exit mass flow rate, the drag coefficient and the orifice diameter. They differ according to different initial conditions or different size of the extinguisher. In this paper we have studied the effect of each of the mentioned parameters with the time needed to discharge.

Finally we notice that the varying the mass flow rate of water not leading to a great changing in the final temperature and final pressure of air at any mass flow rate of water. As varying initial volume of air lead to greatly changing in the final temperature and final pressure of air at any initial volume of air. Also we see that the varying the initial pressure lead to greatly changing in final temperature of air at any initial pressure of air, but the varying the initial temperature not lead to greatly changing in final pressure of air but it made the deviation in the final pressure of air very small that forcing us to consider it same.

The constants in the equation of water exit mass flow rate are only measure experimentally and when initial conditions change, they change and affect the following results.

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Resources and references: 1- <http://www.femalifesafety.org/types-of-fires.html>

2-< http://www.eurofireprotection.com/blog/the-fire-classification-system-in-the-uk/>

3- <http://www.firesafeservices.com.au/fact-sheets/safety_extinguishers.pdf>

4- <http://www.sulekha.com/fire-fighting/fire-fighting-buying-guide>

5- <http://www.firesafetyinfo.co.uk/>

6- <https://www.wormald.com.au/fire-products/fire-extinguishers/extinguisher-selection-and-fire-classification>

7- National Fire Protection Association (NFPA) report issued in September, 2015.

<https://www.usfa.fema.gov/data/statistics/#tab-1>

<http://www.nfpa.org/research/reports-and-statistics>

8- Local authority fire and rescue services in England,

<https://www.gov.uk/government/publications/incident-recording-system-for-fire-and-rescue-authorities>

<https://www.gov.uk/government/statistics/fire-statistics-monitor-april-2014-to-march-2015>

9- Bergman, T. L. and Lavine, A. S. and Incropera, F. P. And Dewitt, D. P., 2006, Fundamentals of heat and mass transfer - 7th edition, John Wiley & Sons, 605, 995.

10- NFPA Guide to Portable Fire Extinguishers, Mark T. Conroy, Editor, First Edition11- Fire safe

<https://www.firesafe.org.uk/history-of-fire-extinguishers/>

12- Traffic Awareness Forum

<http://trafficsafety.mountada.net/t81-topic>

13- Marefa

<h ttp://www.marefa.org/index.php/%D8%B7%D9%81%D8%A7%D9%8A%D8%A9_%D8%AD %D8%B1%D9%8A%D9%82>

14- RDM

<http://www.rdm1.com/brief-history-fire-extinguisher/>

15- Ezine Article

<http://ezinearticles.com/?History-of-the-Fire-Extinguisher---Find-Out-Who-Invented-the-Fire-Extinguisher&id=2158264>

16- Vaari, Jukka., Hostikka, Simo., Sikanen, Topi. and Paajanen, Antti. (2012). Numerical simulations on the performance of water-based fire suppression systems.

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https://www.gov.uk/government/statistics/fire-statistics-monitor-april-2014-to-march-2015

https://www.gov.uk/government/publications/incident-recording-system-for-fire-and-rescue-authorities

http://www.nfpa.org/research/reports-and-statistics

https://www.usfa.fema.gov/data/statistics/#tab-1

https://www.wormald.com.au/fire-products/fire-extinguishers/extinguisher-selection-and-fire-classification

http://www.firesafetyinfo.co.uk/

http://www.sulekha.com/fire-fighting/fire-fighting-buying-guide

http://www.firesafeservices.com.au/fact-sheets/safety_extinguishers.pdf

http://www.eurofireprotection.com/blog/the-fire-classification-system-in-the-uk/

http://www.femalifesafety.org/types-of-fires.html

17- Tanner, Geoff., Knasiak, Keith. F. (2003). Spray Characterization of typical suppression nozzles.

Sources of figures and tables:

Figure (1) – <http://safety108.blogspot.com/2011_09_01_archive.html>

Figure (2) & (6) – NFPA Guide to Portable Fire Extinguishers, Mark T. Conroy, Editor, First Edition.

Figure (4) - <https://www.usfa.fema.gov/data/statistics/#tab-1>

Figure (5) - <https://www.gov.uk/government/publications/incident-recording-system-for-fire-and-rescue-authorities>

Table (2) - <http://www.allfirealarms.com/Fire-extinguisher-types.html>

Table (3) - <http://www.firesafetyinfo.co.uk>

Table (4) - <http://www.exelgard.com.au/product/fire-extinguishers>

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