Study on Water-based Fire Extinguishing Agent Formulations and Properties

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Procedia Engineering 45 (2012) 649 – 654

2012 International Symposium on Safety Science and Technology

Study on water-based fire extinguishing agent formulations and properties HUANG Yinsheng*, ZHANG Wencheng, DAI Xiaojing, ZHAO Yu School of Chemical Engineering, Nanjing University of Science & Technology, Nanjing 210094, Jiangsu, China

Abstract This article uses the orthogonal experimental method to explore seven kinds of additives, including the fluorocarbon surfactant, hydrocarbon surfactant, chelating agents, anti-burning agents, emulsifiers, thickeners and antifreeze, with different content ratio of waterbased extinguishing agent studying the impact of fire extinguishing performance. Get the best theoretical formula by using standard combustion room to simulate the extinguishing process of gasoline fire. The affect size of extinguishing time of those additives is hydrocarbon surfactant> chelating agents> fluorocarbon surfactant> emulsifiers> anti-burning agents> thickeners> antifreeze. According to the national standards for the test methods, the pH, stability, sediment, surface tension, fire performance of the best theoretical formula are consistent with the requirements of national standards. The article also verifies the feasibility of the orthogonal experiment method in dealing with such issues.

© 2012 The Authors. Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Beijing Institute of Technology. Keywords: water-based fire extinguishing agent; orthogonal; additives; performance test

1. Introduction Water is the most commonly used in fire extinguishing agent, but there is losing easily of water flow. By adding additives in the water could improve the efficiency of fire fighting. The main additives of water-based fire extinguishing agent are surfactant additives (including fluorocarbon surfactants and hydrocarbon surfactants), flame retardants, emulsifiers, thickeners, antifreeze and other additives [1-2]. In the early stages of water-based fire extinguishing agent researching, improved the fire fighting performance by changing water flow, wetting, adhesions, spraying methods etc.. Enhanced water, viscous water, and wet water have their own advantages and disadvantages [3-8]. However, one or a small amount of additives added to water the fire fighting performance only have little change. The author hoped that through the various additives performance and studied different ratio to increase a greater degree of water-based extinguishing agent’s performance. In this paper, The author have studied the different proportion relationship of fluorocarbon surfactants and hydrocarbon surfactants, anti-burning agents, emulsifiers, thickeners, chelating agents and antifreeze affect to the fire fighting efficiency. The best theoretical formula is obtained and tests the performance of pH, stability, sediment, surface tension, fire performance of the formula and conforms to the national standards.

* Corresponding author. E-mail address: [email protected]

1877-7058 © 2012 Published by Elsevier Ltd. doi:10.1016/j.proeng.2012.08.217

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HUANG Yinsheng et al. / Procedia Engineering 45 (2012) 649 – 654

2. Experiment 2.1. Experimental device of extinguishing The fire extinguishing experiment had been conducted in a 3m×3m×3m standard combustion room, with a burning oil pan which size was 0.45m×0.45m×0.3m. The gasoline depth in the pan was not less than 5 cm. The surface of the fuel layer was located 15 cm below the top edge of the pan, so that the fire could not be blown away by the discharge of water-based fire extinguishing agent. The fire extinguisher’s pressure was 0.25MPa, and its capacity was 3L. One video camera was set up to obtain visual records of the extinguishing. The video was recorded at approximately 30 frames/s. In the experiment, the gasoline was ignited by using a blow torch and the fire was allowed to burn freely for 1 min before the injection of the extinguishing agent. The water-based fire extinguishing agent attack was made from one side only and the operator was not allowed to extend any part of his body past the edge of the test pan while fighting the fire. The whole device is shown in Fig 1.

Fig. 1. Experimental device of extinguishing

2.2. Extinguishing process Table 1 and Table 2 are the experimental data of gasoline fire extinguishing in standard combustion room. Table 1 is a comprehensive study of the seven kinds of additives. Table 2 has four additives which are selected from table 1 for further analysis. Table 3 is the processing of the data in Table 2. A, B, C, D, E, F, G are respectively on behalf of the seven kinds of additives, the percentage of the mass fraction is accounted for the total quality of the additives not including water quality. Using L8(27) and L9(34) orthogonal experiment tables [9-10] studied seven water-based extinguishing agent additives. They were fluorocarbon surfactant, hydrocarbon surfactant, chelating agents, anti-burning agents, emulsifiers, thickeners, and antifreeze that corresponding to A, B, C, D, E, F, G of the table1 respectively. Additives added to the water and the mass fraction of additives were 3%. In Table 1 each level corresponds to the concentration of A(20%,10%), B(10%,20%), C(2%,4%), D(5%,10%), E(5%,10%), F(5%, 10%), G(8%,16%). I and II are column corresponding to “1” and “2” of the data summation respectively. The data -6.2,4.8,-4.4,-3.8 in the last line of Table 1 shows that the factor A, B, C and E’s affect are relatively large. It’s indicated that the factor A, B, C and E are the main factors for extinguishing time. Table 2 is the major impact factors of the experiment, the factor A, B, C, E correspond to Table 1 A, B, C, E. In Table 2 each level corresponds to the concentration of A(5%,10%,20%), B(10%,20%,30%), C(2%,1%,0%), E(5%,2.5%,0%). I, II and III are column corresponding to “1”, “2” and “3” of the data summation respectively. When S=X2+Y2+Z2 calculated from Table 3, four factors deviation: SA = 1.73, SB = 11.65, SC = 3.33, SD = 0.61. From the results we know that the second factor has the greatest impact than other factors. That means hydrocarbon surfactant has great impact on extinguishing time. Under this conditions, the best ratio is A3B3C1E2. According to the results of the three tables we get a theoretical formula A3B3C1D2E2F2G1.

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HUANG Yinsheng et al. / Procedia Engineering 45 (2012) 649 – 654 Table 1. First stage of fire test data Additive

A

B

C

D

E

F

G

Extinguishing time /s

1

1

1

1

1

1

1

1

18

2

1

1

1

2

2

2

2

21

3

1

2

2

1

1

2

2

18

4

1

2

2

2

2

1

1

20

5

2

1

2

1

2

1

2

35

6

2

1

2

2

1

2

1

25

7

2

2

1

1

2

2

1

21

8

2

2

1

2

1

1

2

21

I

77

99

81

92

82

94

84

Sum

II

102

80

98

87

97

85

95

179

I/4

19.3

24.8

20.1

23.0

20.5

23.5

21.0

179/8=22.4

II/4

25.5

20.0

24.5

21.8

24.3

21.3

23.8

I/4-II/4

-6.2

4.8

-4.4

1.2

-3.8

2.2

-2.8

/Test No.

Average

Table 2. Second stage of fire test data Additive

A

B

C

E

Extinguishing time / s

1

1

1

1

1

20.3

2

1

2

2

2

17.7

3

1

3

3

3

17.5

4

2

1

2

3

21.0

5

2

2

3

1

19.0

6

2

3

1

2

14.0

7

3

1

3

2

20.0

8

3

2

1

3

14.5

9

3

3

2

1

15.5

I

55.5

61.3

48.8

54.8

Sum

II

54.0

51.2

54.2

51.7

159.5

III

50.0

47.0

56.5

53.0

Average

I/3

18.5

20.4

16.3

18.3

159.5/9

II/3

18.0

17.1

18.1

17.2

=17.7

III/3

16.7

15.7

18.8

17.7

/Test No.

Be handled to Table 2. Table 3. Data processing A

B

C

E

X (I/3-Average)

0.8

2.7

-1.4

0.6

Y (II/3-Average)

0.3

-0.6

0.4

-0.5

Z (III/3-Average)

-1.0

-2.0

1.1

0

SA=1.73

SB=11.65

SC=3.33

SD=0.61

2

2

S=X +Y +Z

2

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3. Performance test According to the national standard the water-based fire extinguishing agent of theoretical formula was tested. The items including pH, stability, sediment, surface tension and fire fighting performance. 3.1. pH The calibration of pH meter was done by using pH benchmark reagent. 30ml water-based fire extinguishing agent was injected into a dry clean 50ml beaker under (20±0.5)℃. The electrode into the fire extinguishing agent measured the pH. Repeated the test and took two experimental average value as the measurement results. The difference of the two test results should not be greater than 0.1pH. 3.2. Stability 20L non-concentrated water-based extinguishing agent was prepared to pour into the plastic bucket of 30L volume. First, The samples were placed in the freezer that maintaining the temperature for 24h, and thawed at room temperature that their storage time should be more than 24h and less than 96h. Second, took the samples into (60±3)℃ electric oven and maintained the temperature for 24h. Then the samples were placed at room temperature that storage time should be more than 24h, less than 96h. Repeated this process three times to complete the four cycles of freezing, melting, high temperature test. Observed the sample if there was segregation phenomenon happened. 3.3. Sediment Took two samples, one of the original sample, and the other sample had been done the stability test and mixed well. Two sets of samples were placed in two cone scale centrifuge tubes with 50ml liquid respectively. The tubes were placed into centrifuges symmetrically then covered the lid. The tubes had been centrifuged at (2000±100)r/min for 15min. Removed the centrifuge test tubes, recorded the mean value of precipitate volume percentage as the test results. Washing the sample in the test tube to sieve and observe if the sediment can dispersed through the sieve by water flushing. 3.4. Surface tension Adjusted the temperature of the water-based extinguishing agent to (20±2)℃, and measured the surface tension. Repeated the test, took the average value of the two tests as the test results. 3.5. Extinguishing performance 3.5.1. Class A fire extinguishing experiment Wood crib used in the fire experiments consisted of 0.04m×0.04m×0.5m long spruce. A total of 72 wooden sticks were arranged as the crib with 12 layers that every layer had 6 battens. The crib was constructed upon an iron support frame and mounted on a weighing platform which above the ground level (0.25 0.01)m. A pan with 1.1L gasoline which size of 0.4m×0.4m×0.1m high was placed centrally beneath the crib and acted as an ignition source. The total mass of the crib was measured prior to the experiment. Gasoline in the pan was then ignited manually and the crib was allowed to burn freely until its mass was reduced to 55% of its original mass. At the beginning of the injection of fire extinguishing agent, the direction was the front of the wooden cribs, and the distance was not less than 1.8m. The fire extinguishing was proceeded from five sides of the crib, by discharging continuously. The injection was not allowed to directed at the back of the crib. Any part of the operator and fire extinguishers should not be touched the model. After 10min when the flame went out, there was no visible flame ( non-sustained flame appeared within 10min was not considered, that is, fire fighting succeed). Fire test was conducted three times. If there were two succeeded fire fighting, that affirmed the fire extinguishing agent was this fire fighting level 3.5.2. Class B fire extinguishing test Oil pan of the test was 1.14m in diameter and the depth was not less than 0.2m. The bottom of the gasoline layer by adding water to the pan as the cushion, in order to ensure that the oil level from the top of the plate a distance of

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0.15m±0.005m. Ignited the gasoline (the pre-combustion time was 60s), and began to fire fighting after the end of the precombustion. In the process of extinguishing the fire extinguisher could jet continuously but cannot set foot into the oil pan for fire fighting. After 1min when the flame went out, if the flame did not appear again and there was a surplus of gasoline, then affirmed the fire fighting success. Fire fighting test three times, including two fire fighting success, the fire extinguishing agent of this fire fighting level.

Fig. 2. Extinguishing process of class A

Fig. 3. Extinguishing process of class B

The following are the national standards and experimental data:

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HUANG Yinsheng et al. / Procedia Engineering 45 (2012) 649 – 654

Table 4. National standards compared with experimental data Test project pH value (20

)

Stability Sediment (volume %)

Experimental data

6.5~9.0

7.5

No segregation

No segregation

Before the stability test

0.25;Sediment can through 180μm sieve

0.12; Sediment can through 180μm sieve

After the stability test

1.00;Sediment can through 180μm sieve

0.55; Sediment can through 180μm sieve

35.0

20

Class A fire

1A

1A

Class B fire

4B

5B

Surface tension (20

National standards

), mN/m

Extinguishing performance (3L liquid)

4. Conclusions (1) Through using orthogonal test method to explore several additives on the efficiency of water-based fire extinguishing agent of influence, analyze the impact of various factors, size, and get the best theoretical formulations and the order of affect size. (2) According to the national standards for test method, the performance parameters of the preparation of water-based extinguishing agent are superior to the national regulations. (3) Orthogonal experimental method is feasibility to deal with water-based extinguishing agent additives. References [1] Chow W. K, Jiang Z, Li S. F, Han D. L, 2007. Improving fire suppression of water mist by chemical additives, Polymer-Plastics Technology and Engineering 46, p. 51. [2] A. K. Kim, 2001. "Improvement of water mist performance with foam additives," Fire Suppression and Detection Research Application Symposium", Orlando, US, p. 7-8. [3] ZHOU Xiaomeng, LIAO Guangxuan, 2006. Improvement of water mist’s fire-extinguishing efficiency with MC additive, Fire Safety Journal 41, p. 39. [4] LeFort Georges, W. Andre Marshall, Pabon Martial, 2009. Evaluation of Surfactant Enhanced Water Mist Performance, Fire Technology 45, p. 341. [5] LI Zenghua, ZHOU Shining, 1997. Study and development of water-based extinguisher, China Safety Science Journal 7(2), p. 47. [6] LI Zenghua, ZHOU Shining, 2003. Study on the properties and extinguishing mechanism of viscous water extinguishment, China Safety Science Journal 13(9), p. 41. [7] XU Xiaonan, 2005. Comparison of fire-extinguishing performance for water extinguishing agent series, Fire Safety Science14(4), p. 228. [8] XU Xiaonan, 2003. Research on new water-series extinguisher, Chemical Industry and Engineering Progress 22 (7), p. 717. [9] YANG Shousheng, WANG Xuebao, 2009. Optimizing the multi-compound fire-extinguishing agent by the orthogonal experiment, Fire Science and Technology 28(9), p. 676. [10] Department of Mathematics and Mechanics Peking University, 1979. Orthogonal experiment, Editor. Chemical Industry Press, Beijing, p.1-20.