WO1992001490A1

WO1992001490A1 - Fire extinguishing methods utilizing 1-chloro-1,1,2,2-tetrafluoroethane

Info

Publication number: WO1992001490A1
Application number: PCT/US1991/005138
Authority: WO
Inventors: Mark Lester Robin; Yuichi Iikubo
Original assignee: Great Lakes Chemical Corp
Current assignee: Great Lakes Chemical Corp
Priority date: 1990-07-26
Filing date: 1991-07-22
Publication date: 1992-02-06
Anticipated expiration: 1993-01-26
Also published as: ZA915744B; CA2047800A1; CN1059286A; AU8416891A

Abstract

1-Chloro-1,1,2,2-tetrafluoroethane is a non-ozone-depleting fire extinguishing agent used alone or in blends with other compounds in total flooding and portable systems.

Description

FIRE EXTINGUISHING METHODS UTILIZING 1-CHLORO-l, 1,2,2-TETRAFLUOROETHANE

BACKGROUND OF THE INVENTION

Field of the Invention. This invention relates to fire extinguishing methods utilizing 1-Chloro-l,1,2,2- tetrafluoroethane, HCF2CF2C1.

Description of the Prior Art. The use of certain bromine, chlorine and iodine-containing halogenated chemical agents for the extinguishment of fires is common. These agents are in general thought to be effective due to their interference with the normal chain reactions responsible for flame propagation. It is taught in the art that the effectiveness of the halogens is in the order I > Br > Cl > F, for example, C.L. Ford, in Halogenated Fire Suppressants. R.G. Gann, ed., ACS Symposium Series 16. The use of iodine-containing compounds as fire extinguishing agents has been avoided primarily due to the expense of their manufacture or due to toxicity considerations. The three fire extinguishing agents presently in common use are all bromine-containing compounds, bromotrifluoro ethane (CF3Br), bromochlorodifluoromethane (CF2BrCl), and dibromotetrafluoroethane (BrCF2CF2Br) . It has generally been taught that to be effective as a fire extinguishing agent, a molecule would have to contain bromine, although certain chlorine-containing compounds have been proposed as extinguishing agents, for example chloropentafluoroethane (CF3CF2C1) as described in US Patent 3,844,354 to Larsen.

Although the above named bromine or chlorine-containing agents are effective in extinguishing fires, totally halogenated agents such as CF3Br, CF2BrCl and CF3CF2C1 containing bromine or chlorine are asserted by some to be capable of the destruction of the earth's protective ozone layer.

It is therefore an object of this invention to provide a method for extinguishing fires that extinguishes fires as rapidly and effectively as the present employed agents, and is environmentally safe with respect to ozone depletion.

SUMMARY OF THE INVENTION

The foregoing and other objects, advantages and features of the present invention may be achieved by employing 1-chloro-l,1,2,2-tetrafluoroethane (HCF2CF2C1) and blends thereof with other compounds as fire extinguishants for use in fire extinguishing methods and apparatus. More particularly, the method of this invention involves introducing to a fire 1-chloro-l,1,2,2-tetrafluoroethane in a fire extinguishing concentration and maintaining such concentration until the fire is extinguished.

1-Chloro-l,1,2,2-tetrafluoroethane may be used alone or in admixture with other compounds, optionally in the presence of a propellant. Generally 1-chloro-l,1,2,2-tetra-fluoroethane or its mixtures with other compounds are employed in the range of about 2 to 15%, preferably 4 to 10%, on a v/v basis.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention, 1-chloro-l,1,2,2-tetrafluoroethane has been found to be an effective fire extinguishing agent at concentrations safe for use. However, because 1-chloro-l,1,2,2-tetrafluoroethane contains a hydrogen atom, it has a very low ozone depletion potential due to its removal in the troposphere via reaction with hydroxyl radicals. For example, employing the method of Babson for the estimation of ozone depletion (ODP) values, 1-chloro-l,1,2,2-tetrafluoroethane has an ODP of 0.03, compared to ODP values of 14.26 and 2.65 for the presently employed agents CF3Br and CF2BrCl, respectively, a reduction in ODP of greater than 99% in each case.

1-Chloro-l,1,2,2-tetrafluoroethane has an LC50 value (con- centration necessary to cause death in half of test subjects) of 21% v/v as reported in Simons, Fluorine Chemistry, volume 3, and is hence effective at concentrations well below levels harmful to living things.

1-Chloro-l,1,2,2-tetrafluoroethane may be used alone or in admixture with other compounds, optionally in the presence of a propellant. Among the compounds with which ^• 1-chloro-l,1,2,2-tetrafluoroethane may be blended are chlorine and/or bromine containing compounds such as CF3Br, CF2BrCl, CF3CF2C1, and BrCF2CF2Br. Other compounds forming useful blends with 1-chloro-l,1,2,2-tetrafluoroethane include CF2HBr, CF3CHFBr, CF3CF2H, CF3CHFCF3, CF3CHFC1, CF3CHC12, CF4, CF3H, and similar fluorocarbons. The materials of this invention may also be used in the presence of a propellant, such as N2, C02 or Ar. Where 1-chloro-l,1,2,2-tetrafluoroethane is employed in blends, it is desirably at a level of at least about 5 percent by weight of the blend. 1-Chloro- 1,1,2,2-tetrafluoroethane is preferably employed at high enough levels in such blends so as to minimize the adverse environmental effects of chlorine and bromine containing compounds.

1-Chloro-l,1,2,2-tetrafluoroethane may be effectively employed at substantially any minimum concentration at which the fire may be extinguished, the exact minimum level being dependent on the particular combustible material, and the combustion conditions. In general, best results are achieved where 1-chloro-l,1,2,2-tetrafluoroethane or mixtures and blends are employed at a level of about 4% (v/v) . Likewise the maximum amount to be employed will be governed by matters of economics and potential toxicity to living things. About 15% provides a convenient maximum for use of 1-chloro-l,1,2,2- tetrafluoroethane and its mixtures thereof in occupied areas. Concentrations above 15% may be employed in non-occupied areas, with the exact level determined by the particular combustible material and the conditions of combustion.

1-Chloro-l,1,2,2-tetrafluoroethane may be applied using conventional application techniques and methods used for agents such as CF3Br and CF2BrCl. Thus, the agents may be used in total flooding systems, portable systems or specialized systems. Thus, as is known to those skilled in the art, 1-chloro-l,1,2,2-tetrafluoroethane may be pressurized with nitrogen or other inert gas at up to about 600 psig at ambient conditions.

Practice of the present invention is illustrated by the following examples, which are presented for purposes of illustration but not of limitation. EXAMPLE 1

Concentrations of agent required to extinguish diffusion flames of n-heptane were determined using the cup burner method. Agent vapor was mixed with air and introduced to the flame, with the agent concentration being slowly increased until the flow was just sufficient to cause extinction of the flame. The data are reported in Table 1, which demonstrate the effectiveness HCF2CF2C1. Values for CF3Br and CF2BrCl are included for reference purposes.

Table 1:

Extinguishment of n-heptane Diffusion Flames

Agent Air flow Agent Required Extinguishing Cone, cc/min cc/min % v/v mg/L

EXAMPLE 2

The procedure of example 1 was repeated employing n-butane as fuel. Results are shown in Table 2, and demonstrate the efficacy of HCF2CF2C1 for extinguishment of fires. Table 2 Extinguishment of n-Butane Diffusion Flames

Agent Air flow Agent required Extinguishing Cone, cc/min cc/min % v/v mg/L HCF2CF2C1 16,200 CF2BrCl 16,200 CF3Br 16,200

While the bromine or chlorine containing agents CF3Br and CF2BrCl are somewhat more effective than HCF2CF2C1, the use of HCF2CF2C1 in accordance with this invention remains highly effective and its use avoids the significant environmental handicaps encountered with totally halogenated agents.

Claims

1. A method of extinguishing a fire comprising the steps of introducing to the fire a fire extinguishing concentration of 1-chloro-l,1,2,2-tetrafluoroethane, and maintaining the fire extinguishing concentration until the fire is extinguished.

2. The method of Claim 1 wherein 1-chloro-l,1,2,2- tetrafluoroethane is introduced to the fire at a concentration relative the air surrounding the fire of less than 15% (v/v) .

3. The method of Claim 1 wherein the 1-chloro-l, 1,2,2- tetrafluoroethane is introduced to the fire at a concentration relative the air surrounding the fire of from 3 to 10% (v/v) .

4. The method of Claim 1 wherein said introducing step includes introducing the l-chloro-l,l,2,2-tetrafluoroethane through a total flooding system.

5. The method of Claim 1 wherein said introducing step includes introducing the l-chloro-l,l,2,2-tetrafluoroethane through a portable extinguishing system.

6. A method for extinguishing a fire comprising the steps of: introducing to the fire a fire extinguishing concentration of a mixture comprising: HCF^CF-Cl, and one- or more compounds selected from the group CF₃Br, CF₂BrCl, BrCF₂CF₂Br, CF₃CHFBr, CF₃CHC1₂, CF..CHFC1, CF₃CF₂C1, CF₃CF₂H, CF₃CHFCF₃, CF₂HC1, CF-.H, and CF„ wherein HCF₂CF₂C1 is at a level of at least about 1% by weight of the mixture and maintaining the fire extinguishing concentration of the mixture until the fire is extinguished.

7. The method of Claim 1 where a compound selected from the group nitrogen, CO„, and argon is employed as a propellant.

8. The method of Claim 6 wherein a compound selected from the group consisting of nitrogen, CO_, and argon is employed as a propellant.