Composed typically of acidic and/or alkaline, fire extinguishants significantly corrode metal containers with the passage of time. Accordingly, conventional fire extinguishants suffer from the disadvantage of being difficult to store in containers made of metal such as copper, iron or aluminum, which are used in fire engines and helicopters, for a long time of period.

Therefore, it is an object of the present invention to solve the problems encountered in prior arts and to provide a novel neutral fire extinguishant which does not corrode metal containers.

It is another object of the present invention to provide a method for preparing such a neutral fire extinguishant.

DESCRIPTION OF THE INVENTION The present invention pertains to a fire extinguishant which is neutral in pH so that no oxidative corrosion occurs in metal containers containing it. Thus, the fire extinguishant of the present invention is applicable to fire engines or fire- fighting planes which are usually provided with metal tanks for storing fire extinguishants.

In accordance with the present invention, the fire extinguishant comprises 60 kg of ammonium sulfate ((NH4) 2SO4), 8 kg of urea (CO (NH2) 2), 3 kg of potassium sulfate (K2SO4), 2 kg of potassium carbonate (K2CO3) j l. 5 kg of sodium phosphate (Na3P04), 500 g of an anion surfactant, and 500 g of alum per 100 liters of water. The fire extinguishant of the present invention has a specific gravity of 3.2 and is not frozen at as low as-20 °C. Further, the fire extinguishant of the present invention shows excellent adhesion and penetration properties for wood.

With these advantages, the fire extinguishant of the present invention is particularly useful for the extinguishment of forest fire or fire on structures made of wood. Additionally, application of the fire extinguishant to such wooden or other inflammable structures brings about fire prevention effects. Furthermore, upon firing, a fire line can be constructed by applying the fire extinguishant of the present invention.

Also, the present invention pertains to the preparation of such a fire extinguishant. To 100 liters of water is added 60 kg of ammonium sulfate ((NH4) 2S04) with stirring, to give a solution with a specific gravity of 2.3. Next, 8 kg of urea (CO (NH2) 2) is dissolved in the solution with stirring to give a solution with a specific gravity of 2.7, followed by the addition of 3 kg of potassium sulfate (K2S04) to increase the gravity to 2.9. Subsequently, 2 kg of potassium carbonate (K2CO3) is mixed with the solution by stirring to produce a solution with a specific gravity of 3.1. Afterwards, addition of 1.5 kg of sodium phosphate (Na3PO4) gives a solution with a specific gravity of 3.15 : Also, 500 g of an anion surfactant is added to produce a solution having a specific gravity of 3.2. Finally, the resulting solution is added with 500 g of alum and subjected to precipitation to obtain the fire extinguishant of the present invention.

EXAMPLE 1 A neutral fire extinguishant was prepared as follows.

First Process 60 kg of ammonium sulfate ((NH4) 2SO4) was dissolved in 100 liters of water with stirring to produce a solution with a specific gravity of 2.3.

Second Process 8 kg of urea (CO (NH2) 2) was added to the solution of the first process with stirring to produce a solution with a specific gravity of 2.7.

Third Process 3 kg of potassium sulfate (K2SO4) was added to the solution of the second process with stirring to produce a solution with a specific gravity of 2.9.

Fourth Process 2 kg of potassium carbonate (K2CO3) was added to the solution of the third process with stirring to produce a solution with a specific gravity of 3.1.

Fifth Process 1.5 kg of sodium phosphate (Na3PO4) was added to the solution of the fourth process with stirring to produce a solution with a specific gravity of 3. 15.

Sixth Process

500 g of an anion surfactant was added to the solution of the fifth process with stirring to produce a solution with a specific gravity of 3.2, followed by the addition of 500 g of alum and precipitation.

INDUSTRIAL APPLICABILITY As described above, because conventional fire extinguishants are composed mainly of acidic and/or alkaline compounds, they are apt to corrode metal, suffering from the disadvantage of reducing the lifespan of fire-fighting facilities, particularly metal containers, which are usually mounted onto fire engines and fire-fighting planes. However, the fire extinguishant of the present invention is neutral in acidity and thus does not corrode its metal containers. In addition, the fire extinguishant of the present invention have a specific gravity of 3.2 so that it is not frozen at as low as-20 °C. Further, the fire extinguishant of the present invention shows excellent adhesion and penetration properties for wood. With these advantages, the fire extinguishant of the present invention is effectively used for the extinguishment of forest fire or fire on structures made of wood. Moreover, application of the fire extinguishant to such wooden or other inflammable structures brings about fire prevention effects.

Upon firing, a fire line can be constructed by applying the fire extinguishant of the present invention.

The present invention has been described in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings.. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.