WO2003024537A1

WO2003024537A1 - Fire suppressing and extinguishing compositions

Info

Publication number: WO2003024537A1
Application number: PCT/US2002/030260
Authority: WO
Inventors: Robert G. Richard; David L. Diggs; George A. Shia
Original assignee: Honeywell International, Inc.
Priority date: 2001-09-21
Filing date: 2002-09-23
Publication date: 2003-03-27
Also published as: CA2461131A1; BR0212909A; US20040195544A1; EP1432476A1; MXPA04002657A; JP2005503854A

Abstract

The present invention describes halogenated alkane fire extinguishing compositions consisting essentially of 1,1,1,3,3-pentafluoro propane, optionally pentafluoro ethane, and optionally one or more fire extinguishing fluoro- or chlorfluoroalkanes.

Description

CROSS REFERENCE TO RELATEDAPPLICATIONS

The present application is related to and claims the priority benefit of United

States Provisional Application No.60/323876, which is incorporated herein by

5 reference in its entirety.

FIELD OF THE INVENTION

The present invention is directed toward fire extinguishing compositions and

methods having low ozone depletion potential and low greenhouse gas potential, fire

extinguishing characteristics which compare favorably with the use of bromo-chloro-

.0 difluoro-methane (a highly efficient fire extinguishing agent which is unsuitable for

continued use because of environmental issues).

BACKGROUND

In general, extinguishing agents can be applied to a fire in three manners: 1)

.5 directing a stream of a liquid extinguishing agent at the fire (hereinafter, "streaming

application"); 2) atomizing a liquid extinguishing agent to produce a "mist" or "fog"

of liquid droplets suspended in gas (typically air) and presenting the "fog" to the fire

(hereinafter, "fogging application"); and 3) filling an area within which a fire is

contained with an extinguishing agent in a gaseous state (hereinafter, "flooding

! 0 application"). Flooding application can be carried out by vaporizing a fire extinguishing agent to uniformly occupy the entirety of an enclosed space in which the

fire is contained (total flooding) or by moving a body of the material in the form of a

gas cloud over the region in which the fire is burning, suffocating the fire.

Application of fire extinguishing agent compositions comprising alkanes which

5 have some or all of their hydrogen atoms replaced with halogens (hereinafter "halo-

alkanes", certain subgenus groupings of which are also known in various industries as

"Halons" and "Freons") is generally limited to flooding or streaming. Examples of

these include, for streaming application, bromo-chloro-difluoro-methane (Br(Cl)CF₂),

and for flooding application, bromo-trifluoromethane (BrCF₃).

L 0 Halo-alkanes used as fire extinguishing agents may exhibit a fire extinguishing

effect through: (a) removal of heat energy from a fire (cooling below a level required

to sustain combustion); (b) separating oxygen and fuel through blanketing the fuel

(smothering); and (c) decomposition of the extinguishing agent generating fragments

which effectively terminate the chemical processes sustaining combustion. Various of

L 5 the halo-alkanes exhibit one or more of these properties when applied to a fire. The

method by which the extinguishing agent is applied to a fire has bearing on the degree

to which it is important that the extinguishing agent exhibits these fire extinguishing

processes.

In flooding applications, the fire extinguishing agent must be volatile in all

10 ambient conditions in which the agent is used to insure that the space in which it is

deployed contains sufficient concentration of the fire extinguishing agent to suppress the fire, thus, vapor phase heat capacity and flame suffocating ability are important

aspects associated with a flooding agent. Secondarily, the ability of a flooding agent

to decompose and disrupt the chemical process involved in combustion is also

important.

In streaming applications, the fire extinguishing agent is presented to the fire as

a liquid. In such applications, a high value of liquid to vapor phase heat absorption

(heat of evaporation) becomes important, as well as the vapor phase heat capacity. Of

additional importance in fire extinguishing agents used in streaming applications is the

volatility of the liquid. While high heat absorption in changing phase is desirable, a

streaming agent which is not sufficiently volatile to provide a large volume of

smothering gas upon application to the fire will not readily "knock down" the flame

front of the fire, making it less efficient in extinguishing the fire.

Fogging agents, which are suspended droplets of a liquid extinguishing agent in

a gas, usually air, typically have very high liquid to gas phase change heat of

evaporation and low volatility. An example of a good fogging agent is water.

Typically, fire extinguishing agent compositions based on halo-alkanes have

heretofore been formulated for application as a flooding or streaming agent, and not

for fog application. Among the halo-alkane fire extinguishing agent compositions

known, one that has long been known in the art as having superior performance in

streaming application is bromo-chloro-difluoromethane (Br(Cl)CF₂). Br(Cl)CF₂ is

toxic to humans, and therefore is not used in flooding applications. Even though it is a less efficient fire extinguishing agent, bromo-trifluoromethane (BrCF₃), which is non-

toxic, is used in flooding applications instead of bromo-chloro-difluoromethane.

The use of various halo-alkanes in applications in which they enter the

atmosphere has raised international concern with regard to the ability of these

materials to contribute to destruction of ozone in the upper atmosphere and with

regard to the ability of these gases to also function as "greenhouse" gasses. This

concern has created a need for compositions which exhibit flood and streaming fire

extinguishing agent properties similar to BrClCF₂ and BrCF₃ (hereinafter, "the halo-

methanes") identified above, but which do not posses the negative environmental

impact associated with those materials.

A class of compounds, halo-alkanes of 4 or fewer carbon atoms, have been

identified as having sufficient volatility and heat capacity for use in fire extinguishing

agent compositions and may be candidates for replacing the above-identified halo-

methane compounds by virtue of their low ozone depletion potential and low potential

as greenhouse gasses.

One such compound is 1,1,1,2,3,3,3 heptafluoro-propane. When used as a fire

extinguishing agent it is not as efficient as the halo-methanes it replaces due to its

lower volume of smothering vapor. Another compound, pentafluoroefhane, offers

better smothering vapor than the heptafluoro-propane and is believed to also readily

breakdown in the environment, thus it has potential to replace bromotrifluoro-methane

(BrCF₃) as an extinguishing agent in flood applications. Pentafluoroethane compares favorably with bromotrifluoro-methane, based on a comparison of the vapor phase

heat capacity and ability to deliver a volume of blanketing gas. This implies that

pentafluoroethane is a good candidate for use as a fire extinguishing agent. However,

when pentafluoroethane is used by itself as an extinguishing agent in a flood

application, it is less efficient than the bromotrifluoro-methane it replaces, thus

applicants perceive a continuing need for a replacement with improved efficiency.

It has been suggested (see,U.S. Patent 5,124,053 to Yuichi et al), that blending

various fluoro-alkanes can take advantage of the various indidividual properties of the

fluoro-alkanes and produce compositions which are similar to the properties of the

halo-methanes described above, providing a more suitable fire extinguishing agent

composition for replacing them. Examples of such compositions include compositions

described in published PCT application WO 93/17758, TAG Investments, Inc.,

applicants, (hereinafter, "the '758 application"), which describes two fire

extinguishing compositions for flood applications. A first composition is generically

described comprising one or more fluoro- or chlorofluorcarbon compounds of up to 4

carbon atoms. A second composition is described as containing one or more fluoro- or

chlorofluoro carbon compounds from a list naming about 40 such compounds.

Pentafluoroethane is encompassed within this list. However, pentafluoroethane alone

is unsuitable for use as a fire extinguishing agent in streaming applications. Because

of its low boiling point, when pentafluoroethane is applied as a stream it disperses

before it reaches the fire, making it unsuitable for use out-of-doors. All of the compositions described in the '758 application also include from about 0.1 to about 10

wt. % of an acid scavenging compound of the type further described below.

U.S. Patent Nos. 5,393,438 and 5,141,654, both to Fernandez, (hereinafter, "the

'438 patent" and "the '654 patent", respectively) both describe fire extinguishing agent

compositions, which are adaptable for use in flooding applications and which

comprise pentafluoroethane or a mixture of pentafluoroethane and one or more

propane compounds selected from a list comprising chloro-flouoropropanes, hexa- and

heptafluoropropanes. Neither of the '438 patent nor the '654 patent describes the use

of these compositions as streaming or fogging agents.

Published PCT application WO 95/26218 describes fire extinguishing agent

compositions for use as flooding agents which comprise one or more fluorocarbon

compounds of the formula C_xH_yF_z, where "x" = an integer and "y+z" = "2x+2", and an

acid scavenging compound comprising terpenes, unsaturated oils, and alkali metal

compounds of bicarbonate, phosphate, halide, and urea. These compositions are

described as being suitable for use as total flooding agents. This publication does not

describe a fire extinguishing agent suitable for streaming or fogging applications, nor

does it mention or suggest the use of 1,1,1,3,3 pentafluoropropane alone or in

combination with pentafluoroethane.

Applicants have come to appreciate the need for an improved method of

extinguishing a fire in situations where there is no "line of sight" between the source

of the fire extinguishing agent and the fire, such as where the fire is in a confined space or under a cover or cowl. It has been heretofor common to use a flooding

method in such situations. Compositions which are sufficiently volatile to be

employed as a flooding agent have heretofore been unsuitable for application as

streaming or fogging fire extinguishing agents. This is because flooding agents and

methods have been designed to vaporize the agent to the gas phase before application

to the fire, whereas streaming and fogging agents must be applied to the situs of the

fire as a liquid in order to taking advantage of the heat capacity involved in converting

the liquid to a gas.

Applicants have come to recognize that heretofor used streaming agents, as

discussed above, suffer from the relative inability to provide sufficient suffocating

volume after application to the fire, which generally requires relatively high volatility,

while at the same time being of sufficiently low volatility to avoid dissipation of the

liquid prior to contact with the situs of the fire.

SUMMARY OF THE INVENTION

Applicants have discovered compositions which tend to overcome some or all

of the above-noted disadvantages of the prior art, and others which are not mentioned

above.

One aspect of the present invention involves a method of extinguishing a fire

comprising providing a fire extinguishing agent comprising pentafluoropropane and optionally pentafluoroethane, generating a fog of said fire extinguishing agent and

introducing said fog to the fire. In preferred embodiments, the methods comprise

introducing said fog to the fire by releasing the fog from a location that not in the line

of sight of the fire.

Although applicants do not wish to necessarily be bound by or to any particular

theory of operation, it is believed that 1,1,1,3,3-pentafluoropropane has excellent

performance as a replacement for bromochlorodifluoromethane (BrClCF₂) in

streaming applications because at temperatures above 412 °C it displays facile

decomposition. It is believed that this decomposition property gives 1,1,1,3,3-

pentafluoropropane an exceptional ability to readily participate in free radical

scavenging when exposed to a fire.

Applicants have also discovered that, in certain applications, the use of

1,1,1,3,3-pentafluoropropane can be further improved by the addition of

pentafluoroethane to the composition. Although it has similar heat capacity to

bromochlorodifluoromethane, when 1,1,1 ,3, 3 -pentafluoropropane is applied to a fire it

may not always produce as much smothering vapor as the halomethane. In such

situations, it may provides adequate cooling to extinguish a fire, but may not exhibit

rapid flame front "knock down" properties (fire smothering ability) comparable to

halomethane. The use of pentafluoroethane and 1,1,1,3,3-pentafluoropropane together

in the present compositions provides a fire extinguishing agent which in many cases is

comparable to or exceeds the fire extinguishing efficacy of halomethane. One aspect of the present invention provides a fire extinguishing agent

comprising, and preferably consisting essentially of, pentafluoroethane and

pentafluoropropane, preferably 1,1,1,3,3-pentafluoropropane. In certain preferred

embodiments, 1,1,1,3,3-pentafluoropropane is present in the composition in amount of

at least about 20 wt.% of the composition. In other embodiments, the composition

comprises at least about 6 wt% pentafluoroethane. Preferably, the composition

comprises at least about 6 wt% pentafluoroethane and at least about 20 wt.% of

1,1,1 ,3,3-pentafluoropropane.

Compositions of the present invention can optionally contain up to about 10

wt.% additional of a hydrogen fluoride ("HF") scavenging agent. Preferably when an

HF scavenging agent is employed it is comprises from about 2 wt% and about 10 wt%

of the composition.

Another aspect of the present invention is the provision of a fire extinguishing

agent in the form of a fog made from a composition comprising, and preferably

consisting essentially of, pentafluoroethane and from about 1 wt% 1,1,1,3,3-

pentafluoropropane to about 80 wt.% 1,1,1,3,3-pentafluoropropane.

agent in the form of a stream made from a composition comprising, and preferably

consisting essentially of, pentafluoroethane and from about 45 wt% to about 94 wt.%,

and even more preferably from about 64 wt % to about 94 wt. %, of 1 , 1 , 1 ,3,3-

pentafluoropropane. According certain preferred embodiments, the fire extinguishing stream of the present invention is formed using a composition comprising from about

20 wt. % to about 36 wt. % of pentafluoroethane and at least about 45 wt. %, of

1,1, 1 ,3,3-pentafluoropropane.

Another aspect of the present invention is the provision of a method of

extinguishing a fire by providing a fire extinguishing composition of the present

invention to a fire as a stream of fire extinguishing agent comprising

1,1,1,3,3-pentafluoro propane and pentafluoroethane wherein the

1,1,1,3,3-pentafluoropropane is present in amount of at least about 45 wt.% of the

composition and the pentafluoroethane is present to a level of at least 6 wt.% of the

composition.

Optionally, the stream application fire extinguishing composition can contain

up to about 10 wt% additional of an HF scavenging agent. Preferably, when an HF

scavenging component is employed it is added to the composition to a level of

between about 2 wt.% and about 10 wt. % additional.

Another aspect of the present development is the provision of a method of

extinguishing a fire by providing the fire extinguishing composition of the present

development to a fire as a fog of fire extinguishing agent comprising a mixture of

1,1,1,3,3-pentafluoro propane and pentafluoroethane wherein the pentafluoropropane

is present to a level of at least 1 wt.% of the composition and the pentafluoroethane is

present to a level of at least 20 wt.% of the composition.

Optionally, the fog application fire extinguishing agent can have up to about 10 wt% additional of an HF scavenging agent.

Other features of the present invention will be pointed out in the following

description and claims, which disclose but do not necessarily limit the broad aspects

of the present invention, the principles of the invention.

In certain preferred embodiments, the present compositions do not contain fire

extinguishing amounts of any compounds that are completely fluorinated and/or any

compounds that contain chlorine. Preferably in such embodiments, the present

compositions do not contain any substantial amount of, and even more preferably are

substantially free of, any compounds that are completely fluorinated and/or any

compounds that contain chlorine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

DEFINITIONS

Effectiveness in extinguishing fires is measured by the amount of an agent

required to extinguish a standard fire within a specified time. Such tests can be

performed using, for example, a cup burner or other extinguishing concentration

measurement. A recitation of this method as a standard test of effectiveness can be

found in the 2000 edition of "NFPA 2001 Standard on Clean Agent Fire Extinguishing

Systems" Appendix B Cup Burner Test Procedure. Efficiency is measured by the speed with which the flame front of a standard

fire is "knocked down" upon commencing the application of an extinguishing agent,

and the amount of extinguishing agent that is required to be applied to the site to

extinguish a standard fire. Efficiency can be quantified using either UL testing

standard 2166 or the standard cup burner test described above.

As the term is used herein, alkanes having a majority of the hydrogens replaced

with fluorine (hereinafter "highly fluorinated" alkanes) and those with all of the

hydrogen replaced by fluorine (hereinafter "completely fluorinated" or

"perfluorinated" -alkanes) are those surmised to be not as likely to participate in ozone

destruction as the analogous chloro, chloro/fluoro, and bromo compounds. The

stability of these materials, however, raises concerns that their presence in the

atmosphere can impede re-radiation of heat from the earth, leading to global warming.

For this reason, highly fluorine substituted and perfluorinated alkanes have been

implicated as greenhouse gases. Less highly fluorine substituted alkanes (hereinafter

"partially fluorinated") are those that are thought to be subject to more facile

breakdown in the environment, and therefore have a lesser global warming potential.

COMPOSITIONS OF THE PRESENT DEVELOPMENT

As discussed above, pentafluoroethane and 1,1,1,3,3-pentafluoropropane are

"partially fluorinated" fluoro-alkanes which have been identified as potential replacements for the halo-methane fire extinguishing agents described above. When a

fire is small, 1,1,1,3,3-pentafluoropropane may be used by itself as a replacement

streaming agent for bromochlorodifluoromethane, or with other halogenated alkanes

having similar physical characteristics. In applications where chlorinated materials

may be tolerated various fluoro- or chloro-/fluoro- alkanes may be substituted for or

used in addition to pentafluoroethane to yield desirable fire extinguishing

compositions. Thus, alternative or additional low and high boiling fluoro and chloro

fluoro alkanes may be blended with 1,1,1,3,3 pentafluoropropane to provide for fire

extinguishing agent compositions which may be used in stream or mist applications.

Examples include, but are not limited to HC(C1)F₂ (HCFC-22), HCF₃ (HFC-23), F₃C-

(H)CC1₂ (HCFC-123), F₂C(C1)-(H)C(F)C1 (HCFC-123a), C1₂C(F)-(H)CF₂ (HCFC-123b), F₃C-(H)C(F)C1 (R124), F₂C(C1)-(H)CF₂ (R124a ), F₂C(H)-(H)CF₂ (R134), F₃C-(F)CH₂ (R134a ), H(F)C(C1)-(H)C(F)C1 (HCFC 132), F₃C-(H)C(F)-CF₃ (HFC-227ea), F₂C(H)-C(F₂)-CF₃ (HFC-227ca), F₃C-C(H₂)-CF₃,(HFC-236fa), F₂C(H)-(H)C(F)-CF₃ (HFC-236ea), H₂C(F)-(CF₂)-CF₃ (HFC-236cb), F₂C(H)-C(H₂)-CF₃ (HFC-245fa),

F₂C(H)-(H)C(F)-(H)CF₂ (HFC-245ea), H₂C(F)-(H)C(F)-CF₃ (HFC-245eb),

H₃C-C(F₂)-CF₃ (HFC-245cb), ICF₃.

As described above, where fire extinguishing efficiency in a fire extinguishing

agent is required, for example, in fighting large fire, use of 1,1,1,3,3-

pentafluoropropane or pentafluoro ethane alone has not proved to be a fully adequate

replacement in all applications, and blends containing either of these materials suitable for streaming and fogging application in fighting fires have not been heretofore

identified.

It has now been found, surprisingly, that by combining, preferably to a

substantially homogenous mixture or blend, pentafluoroethane with 1,1,1,3,3

pentafluoropropane, the efficiency of the resulting composition when used as a

streaming application fire extinguishing agent is improved to the point where it

compares favorably with bromo-chloro-difluoro-methane in many applications.

Without wanting to be bound by theory, it is believed that the improvement in

the performance of the pentafluoropropane/pentafluoroethane combinations over

pentafluoropropane alone is due to the low boiling component supplying a sufficient

volume of a gas that has good smothering properties and sufficient heat capacity to

impart rapid "knockdown" of the flame front, while providing a sufficient heat

capacity between the gas phase component and liquid phase component dispersed as

fine droplets therein that the blend retains adequate cooling properties as well. A

blend made from pentafluoroethane and 1,1,1 ,3 ,3-pentafluoropropane is especially

desirable because incorporation of the low boiling pentafluoroethane provides a vapor

pressure to the composition that is sufficient to propel the liquid from a storage

container in a stream application mode without the use of an additional propellant

charge, although typically, a super pressure of gas, for example nitrogen, can also be

used for this purpose. Preferred blends of pentafluoroethane and 1,1,1,3,3-pentafluoropropane have a

boiling range (defined as the "bubble point" to "dew point" of the material measured,

as detailed in Experimental Thermodynamics Volume II, Edtors B. Le Neindre and B.

Vodar (1975), page 780) that includes the boiling point of

bromochlorodifluoromethane (- 4°C). Thus, a blend of 6 wt. % pentafluoroethane and

94 wt. % 1,1,1,3,3-pentafluoropropane exhibits a - 4°C "bubble point" and a blend of

55 wt% pentafluoroethane/ 45 wt.% 1,1,1,3,3-pentafluoropropane exhibits a - 4°C

"dew point". Blends comprising 44 wt.% 1,1,1,3,3-pentafluoropropane with the

balance consisting of pentafluoroethane have also been found to exhibit a - 4°C

"bubble point". This similarity of physical properties indicates that such blends may

be adequate to replace the halogenated methane now used in streaming applications.

Additionally, blends consisting essentially of pentafluoroethane and 1,1,1,3,3-

pentafluoropropane having between 74 and 94 wt.% of the pentafluoropropane can be

made that have the same or greater ability to remove heat from a fire that is exhibited

by a streaming agent currently used to replace bromochlorodifluoromethane, 1 , 1

dichloro-2,2,2 trifluoroethane. An example of such a blend comprises 23 wt%

pentafluoro-ethane and 77 wt.% 1,1,1,3,3-pentafluoropropane.

It has been additionally found that blends of the pentafluoroethane and

1,1,1,3,3-pentafluoropropane can be employed as a suspension of droplets, for

example a fog or a mist, hereinafter "a fog dispersion", produced using conventional

equipment typically employed to deliver water as a fog in air dispersion. It has been suprisingly found that this type of a fog dispersion has "flood agent-like"

characteristics which can be used to extinguish fires in situations where a flood

application of the fire extinguishing agent is used.

Blends consisting essentially of pentafluoroethane and 1,1,1,3,3-

pentafluoropropane that make good candidates for such fogging application

extinguishing agents have pentafluoroethane present in an amount between about 20

wt. % to about 99 wt. %. Fire extinguishing fog dispersions of these blends have been

found to have the same heat capacity as heptafluoropropane when used as an

extinguishing agent in flood applications. Additionally, they have the same efficiency

as that demonstrated by flood application of the bromodichlorofluoromethane. As

well, it will be appreciated by one of ordinary skill in the art that fogs of the blend of

pentafluoroethane and 1,1,1,3,3 - pentafluoropropane can be employed to extinguish

enclosed fires, and as well, passed through labyrinthian passageways in the same

manner that single molecule flood agents are employed. As well, it will be

appreciated that these fog dispersions can afford improved efficiency in fire

extinguishment over the single molecule compounds previously used to replace

bromotrifluoromethane in such applications.

It is known that when hydrogen and fluorine atoms are present in the same

molecule (as in the case of partially or highly fluorinated alkanes), the compounds

tend to generate HF upon decomposition. HF is highly corrosive to materials and

represents a danger to humans occupying the air space where it is present. Copious HF generation is particularly acute in compounds that have a high ratio of hydrogen to

fluorine. In fire extinguishing agent compositions employing such fluoroalkanes, a

scavenger of HF is included in the formulation. This permits the use of such materials

as components in fire extinguishing agents employed in confined space occupied by

humans, or in the presence of equipment or material which is damaged by the

corrosive effects of HF. Acid scavenging molecules are easily included in fire

extinguishing agent compositions. In this manner they are delivered to a fire along

with the fire suppressing components, and so their presence at the point of HF

generation is insured. Suitable acid scavenging compounds for use in both streaming

and flooding agents are, for example, disclosed in published patent applications WO

93/17758 and WO 95/26218 and U.S. Patent 4,954,271 to Green.

Extinguishing agent compositions of the present invention may also incorporate

an effective amount of an HF scavenging agent in their formulation to mitigate

problems caused by the HF generated when fluoroalkanes of the present invention

compositions are heated in the process of extinguishing a fire. Examples of agents

known to have HF scavenging properties are beta-carotene, citral, citronellol,

citronnellal, para-cymeme, camphor, lanosterol, limonene, lutein, lycopene,

menthadiene, menthol, myrcene, ocimene, oleanolic, dipentene, alpha-pinene, beta-

pinene, phytol, sabinene, saponin, squalene, sylvestrene, terpinene, alpha-terpineol,

terpinolene, turpentine, vitamin A, zingiberene, oleic acid, eleostearic acid, palmitoleic

acid, linoleic acid, lincanic acid, petroselenic acid, abietic acid, linolenic acid, ricinoleic acid, vaccenic acid. Additional examples may be found as well in U.S.

Patent 4,954,271 to Green and in published PCT applications W095/26218 and WO

93/17758, the disclosures of which are incorporated herein by reference. It will be

appreciated by one skilled in the art that mixtures of the various acid scavenging

compounds may additionally be used to scavenge HF generated during extinguishment

of a fire.

Generally, acid scavenging compounds are added to the fire extinguishing

composition in an amount between about 0.1 and 10 wt% of the composition. ..

Preferably, they are added in an amount that is between about 2.0 wt% to about 10 wt.

% of the fire extinguishing composition.

Preparation of Fire Extinguishing Agent Compositions

The compositions of the present invention may be prepared by mixing the

components in a sealed vessel, starting with the least volatile component first, in a

manner familiar to those skilled in blending condensible gas. Thus, for example, a

composition comprising 10 wt% of an acid scavenging component, 80 wt.% of

1,1,1,3,3-pentafluoropropane, and 10 wt% of pentafluoroethane will be prepared by

first placing a weight of the acid scavenging component into a sealed gas cylinder,

condensing a weight of 1,1,1,3,3-pentafluoropropane into the cylinder eight times as

much as the weight of acid scavenging component initially charged, followed by condensing into the gas cylinder a weight of pentafluoroethane equal to the weight of

the acid scavenging component initially charged into the cylinder. The mixture can

then be left to statically blend, or be dynamically blended by rolling or otherwise

agitating the cylinder.

It will be appreciated that other known means of blending volatile liquids and

of blending liquid and condensible gas components may be equally effective in

preparing compositions of the present invention.

Examples

Calculations modeling the discharge behavior of extinguishing agent

compositions comprising a blend of 1 , 1 , 1 ,3,3-pentafluoropropane with

pentafluoroethane present in amounts varied between 0 and 55 mole % were studied.

In a typical determination, an amount of the composition is assumed to be discharged

from a container using a driving pressure of 600 psig to drive the discharge. The

calculations were carried out by assuming an amount of the composition in a sealed

vessel equilibrated to the ambient temperature. Further, it is assumed that the

composition is then released from the vessel under the force of the driving pressure

through a standard orifice developing a directed stream. During discharge, the

composition and temperature of the stream and vapor of the discharged material were

calculated based on adiabatic expansion of the material. This determination was carried out for eight example blends, with the results listed below in Table 1.

Table 1

Inspection of the data in Table 1 shows that increasing the percentage of low

boiling constituents increases the amount of low boiling constituent comprising the

vapor to a greater degree than it increases the presence of the low boiling constituent

in the liquid discharged.

During these discharge tests, the volume of the vapor discharged with the

stream was calculated, and the heat of vaporization of a liquid having the composition

of the discharged stream was calculated in each case. In each case, the calculated

volume of vapor discharged represents the relative amount of suffocant available from each composition. Heat removal calculations were performed by assuming a final

vapor temperature of 412 °C, the auto ignition temperature of 1,1,1,3,3-

pentafluoropropane. At or above the autoignition temperature, decomposition of the

pentafluoropropane is facile, and radical scavenging by the decomposition products

will become significant in the process of extinguishing a fire to which such a

composition is directed. These results are presented below in Table 2.

Table 2

* Heat energy required to change the composition from a liquid at the discharge temperature to a gas with a temperature of 412 °C.

** ml vapor generated/g of composition discharged It can be seen that as the pentafluoroethane content of the liquid is increased, the heat

removal ability of the composition decreases and the smothering volume produced by

the composition increases monotonically with the increase in pentafluoroethane

content.

The heat capacity and smothering behavior of compositions of the present

invention fire extinguishing agent, as reported in Tables 1 and 2, can be compared

with those of a prior art flooding agent (1,1,1,2,3,3,3 heptafluoropropane) and with a

prior art streaming agent (1,1 dichloro, 2,2,2 trifluoroethane). The flooding agent is

known to produce a smothering volume of 47.1 ml/g. The streaming agent is known

to remove 76649 kilojoules/kg-mole when it is converted from a liquid to a 412 °C

gas. By choosing a composition comprising between about 20 wt. % to about 36 wt.

% pentafluoroethane and the balance substantially 1,1,1,3,3 pentafluoropropane, the

smothering capability of the flooding agent and the heat capacity of the streaming

agent can be achieved in a single composition. A composition within this range can

then be used either in a stream application, or dispersed in a fog application and

employed as a flooding agent, depending upon the equipment from which it is

discharged. Cup Burner Tests of Various Compositions

Comprising 1,1,1,3,3 Pentafluoropropane and Pentafluoroethane.

Cup burner tests were run according to testing protocol listed in the 2000

edition of "NFPA 2001 Standard on Clean Agent Fire Extinguishing Systems"

Appendix B "Cup Burner Test Procedure" using binary blends of pentafluoroethane

(hereinafter, "R125") and 1,1,1,3,3 pentafluoropropane (hereinafter, "R245fa") as an

extinguishing agent. The fluoroalkanes from which the blends were made were

sourced from Honeywell. They had a purity exceeding 99.5%, and were used as

received. The volumetric ratio of the two components comprising the extinguishing

agent was varied by varying the flow rate of the two constituents admitted in gaseous

form into the air stream of the cup burner apparatus. The flow rate of the various

components was controlled using an Environics^® gas mixer equipped with flow meters

calibrated for the gasses used.

Initially, the cup-burner apparatus was calibrated using pure R 125 as an

extinguishing agent. In this manner it was determined that an air stream flow rate of

25 1/min required the highest volume percent (8.4 Vol. %) of R125 to be introduced

into the air stream to extinguish the test flame, and this flow rate of burner air was

employed throughout the tests. Cup-burner tests were repeated using 25 1/min of air

stream flow into which was introduced a fire extinguishing agent comprising 0, 2.4,

4.8, 7.0, 9.1, 10.5, 11.3, 13.3, 15.5, 15.7, 17.6, 18.7, 19.8, 20.3, 27.1, 31.0, 35.0, 41.6, 48.4, and 62.5 Vol. % R245fa with the balance of extinguishing agent volume

comprising R125. The amount of this blended extinguishing agent which had to be

introduced into the burner air stream to extinguish the test flame (expressed as a

volume percent of the extinguishing agent in the air stream) is presented graphically in

Figure 1 for each blend tested.

Figure 1 presents three traces, a base line trace, a trace of the above-described

test data, and a trace of "no-effect blend" data, further described below. The test data

trace of Figure 1 is in the form of a black diamond located at the value (in volume %

of burner air) recorded for each extinguishing agent composition tested (described

above), the base line trace is a line comprising alternating long and short dashed, and

the "no-effect blend" trace is a dotted line.

The base line of Figure 1, a horizontal line at 8.4 Vol % of extinguisher

composition in the burner air stream, is the amount of pure R125, expressed as Vol. %

of the burner air stream, required to extinguish the test flame, as described above.

The "no-effect blend" trace, the upper-most curve of Figure 1 , is based on the

notion that a composition comprising a diluent having no fire extinguishing properties

and R125 would be effective in extinguishing the cup burner flame when a sufficient

volume percent of the composition was introduced into the burner air stream that the

R125 present therein accounted for 8.4 Vol. % of the cup burner air stream. To

generate the "no-effect blend" data, a theoretical binary blend comprising R125 and a

diluent having no fire extinguishing properties was postulated. For any given ratio of R125 and diluent, the volume percent of the "no-effect blend" indicated as adequate to

extinguish the burner flame is that amount (expressed as a volume percentage of the

burner air stream) which would be required of the given indicated composition to be

introduced into the burner air stream to provide burner air containing 8.4 Vol % of

R125.

The test data trace, the middle trace in Figure 1, is indicated by a series of black

diamonds located at the amount of composition (in vol. % of burner air) of the various

binary extinguishing agent blends tested, as described above. This trace indicates that

the extinguishing agent "blends" of the present invention perform significantly better

than the theoretical "no effect" binary blends described above. This data also

indicates that pure R125 vapor alone is a more efficient extinguishing agent than the

vapor of an R125/R245fa blend.

It will be appreciated that the cup burner test does not take into account that the

physical characteristics of pure R 125, as described above, which make it unsuitable for

use as a fire extinguishing agent in the form of a "stream" or "fog", and as such the

test can not indicate its suitablity for use as a "streaming" or "fogging" agent. As

described above, the fire extinguishing agent comprising a blend of R245fa and R125

of the present invention are intended to replace those used in streaming application (a

fire extinguishing agent in the form of a stream) or as a dispersion of liquid droplets (a

fire extinguishing agent in the form of a fog). Thus, when the unsuitablity of R125

alone is taken into account, and in consideration of the data presented in Figure 1 and Tables 1 and 2 above, it is clear that blends of R125 and R245fa provide an effective

fire extinguishing agent which has the physical properties suitable for use in fogging

or streaming applications.

As an added benefit, the blended compositions display vapor pressures of up to

about 165 psig when contained at ambient temperature. Thus, present invention

compositions may be charged into standard fire extinguishing equipment, and

discharged therefrom using standard propellant systems.

A preferred fire extinguishing agent in the form of a stream which has superior

fire extinguishing properties from the standpoint of rapid "knockdown" of flame and

good cooling and smothering characteristics when the stream is applied to a fire is

made from a composition having between 0 and about 55 wt. % pentafluoroethane

with the balance substantially consisting of 1,1,1,3,3-pentafluoropropane. Even more

preferred is a stream made from a composition having from about 20 wt. % to about

36 wt. % pentafluoroethane with the balance substantially consisting of

1,1,1,3,3-pentafluoropropane.

A preferred fire extinguishing agent in the form of a fog which exhibits rapid

"knockdown" of the flame front and possesses good cooling and smothering

characteristics when the dispersion is applied to a fire is made from a composition

having more than about 20 wt% pentafluoroethane with the balance substantially

consisting of 1 , 1 , 1 ,3, 3 -pentafluoropropane.

Claims

What is claimed is:

1. A fire extinguishing composition comprising a fire extinguishing effective

amount of 1,1,1,3,3-pentafluoro propane and optionally one or more fire

extinguishing fluoro- or chlorofluoroalkanes.

2. The composition of claim 1, wherein said one or more fire extinguishing

fluoro- or chlorofluoroalkanes are present in the composition and are selected

from the group consisting of HC(C1)F₂ (HCFC-22), HCF₃ (HFC-23), F₃C-(H)CC1₂

(HCFC-123), F₂C(C1)-(H)C(F)C1 (HCFC-123a), C1₂C(F)-(H)CF₂ (HCFC-123b), F₃C- (H)C(F)C1 (R124), F₂C(C1)-(H)CF₂ (R124a ), F₂C(H)-(H)CF₂ (R134), F₃C-(F)CH₂ (R134a ), H(F)C(C1)-(H)C(F)C1 (HCFC 132), F₃C-(H)C(F)-CF₃ (HFC-227ea),

F₂C(H)-C(F₂)-CF₃ (HFC-227ca), F₃C-C(H₂)-CF₃,(HFC-236fa), F₂C(H)-(H)C(F)-CF₃ (HFC-236ea), H₂C(F)-(CF₂)-CF₃ (HFC-236cb), F₂C(H)-(H)C(F)-(H)CF₂(HFC-245ea), H₂C(F)-(H)C(F)-CF₃ (HFC-245eb),

H₃C-C(F₂)-CF₃ (HFC-245cb), ICF₃.

3. The composition of claim 1 wherein said one or more fire extinguishing fluoro-

or chlorofluoroalkanes comprises pentafluoroethane.

4. A fire extinguishing composition comprising a fire extinguishing effective

amount of 1,1,1,3,3-pentafluoropropane and up to about 55 wt. % pentafluoroethane.

5. The composition of claim 4 wherein said pentafluoroethane is present in an

amount up to about 36 wt.% of the composition.

6. The composition of claim 4 wherein said 1 , 1 , 1 ,3,3 pentafluoro propane and said

pentafluoroethane are present in amounts effective to provide said composition

with a boiling point range encompassing -4° C.

7. The composition of claim 6 wherein said 1,1,1,3,3 pentafluoro propane is

present in the composition in an amount of at least about 74 wt% of said

composition.

8. The composition of claim 6 wherein said pentafluoroethane is present in the

composition in an amount of from about 20 wt.% to about 36 wt.% of said

composition.

9. The composition of claim 3 wherein said pentafluoroethane is present in the

composition in an amount of from about 20 wt.% to about 99 wt.% of said

composition.

10. A fire extinguishing fog comprising a composition consisting essentially of

pentafluoroethane and from about 1 wt% to about 80 wt.%

1,1,1 ,3 ,3-pentafluoropropane.

11. The fire extinguishing fog of claim 10 further comprising an effective amount

of an HF scavenging agent.

12. The fire extinguishing fog of claim 11 wherein said HF scavenging agent is

selected from the group consisting of beta-carotene, citral, citronellol,

citronnellal, para-cymeme, camphor, lanosterol, limonene, lutein, lycopene,

menthadiene, menthol, myrcene, ocimene, oleanolic, dipentene, alpha-pinene,

beta-pinene, phytol, sabinene, saponin, squalene, sylvestrene, terpinene, alpha-

terpineol, terpinolene, turpentine, vitamin A, zingiberene, oleic acid, eleostearic

acid, palmitoleic acid, linoleic acid, lincanic acid, petroselenic acid, abietic

acid, linolenic acid, ricinoleic acid, vaccenic acid.

13. A fire extinguishing stream comprising a composition consisting essentially of

pentafluoroethane and from about 45 wt% to about 94 wt.%

1,1,1 ,3,3-pentafluoropropane.

14. The fire extinguishing stream of claim 13 wherein said 1,1,1,3,3-pentafluoropropane is present in an amount of from about 64 wt% to

about 94 wt.% of said composition.

15. The fire extinguishing stream of claim 13 wherein said composition further

comprises an effective amount of an HF scavenger.

16. The fire extinguishing stream of claim 14 wherein said composition further

comprises an effective amount of an HF scavenger.

17. The fire extinguishing agent of claim 15 wherein said HF scavenger is selected

from the group consisting of beta-carotene, citral, citronellol, citronnellal, para-

cymeme, camphor, lanosterol, limonene, lutein, lycopene, menthadiene,

menthol, myrcene, ocimene, oleanolic, dipentene, alpha-pinene, beta-pinene,

phytol, sabinene, saponin, squalene, sylvestrene, terpinene, alpha-terpineol,

terpinolene, turpentine, vitamin A, zingiberene, oleic acid, eleostearic acid,

palmitoleic acid, linoleic acid, lincanic acid, petroselenic acid, abietic acid,

linolenic acid, ricinoleic acid, vaccenic acid.

18. A method of extinguishing a fire comprising the steps of:

(a) streaming a fire extinguishing composition comprising the

composition of claim 13 at a fire; and (b) maintaining said stream for a time sufficient to substantially diminish

< the fire, and optionally until said fire is extinguished.

19. The method of claim 18 wherein said fire extinguishing composition comprises

1,1,1,3,3 pentafluoro propane and pentafluoroethane, said composition having a

boiling point range encompassing -4° C.

20. The method of claim 19 wherein said fire extinguishing composition comprises

from about 20 wt. % and to about 36 wt. % of said pentafluoroethane.

21. A method of extinguishing a fire comprising the steps of:

(a) dispersing the composition of claim 9 as a fog;

(b) directing said fog into an area such that it contacts the fire; and

(c) continuing said directing step for a time sufficient to substantially

diminish the fire, and optionally until said fire is extinguished.

22. The method of claim 21 wherein said fire extinguishing composition comprises

from about 20 wt. % to about 36 wt. % of said pentafluoroethane.

23. A method of extinguishing a fire comprising the steps of:

(a) contacting the fire extinguishing composition of claim 1 at a fire; and (b) maintaining said contact for a time sufficient to substantially

diminish the fire, and optionally until said fire is extinguished.

24. The method of claim 23 wherein said fire extinguishing composition has a

boiling point range encompassing -4° C.

25. The method of claim 23 wherein said fire extinguishing composition comprises

from about 6 wt. % to about 26 wt. % of said pentafluoroethane.

26. A method of extinguishing a fire a fire comprising the steps of:

(a) dispersing the composition of claim 3 as a fog;

(b) directing said fog into an area such that substantially engulfs the fire;

and

(c) continuing the steps of dispersing and directing for a time sufficient

to substantially diminish the fire, and optionally until said fire is

extinguished.

27. The method of claim 26 wherein said fire extinguishing composition comprises

from about 20 wt. % to about 99 wt. % pentafluoroethane.

28. The stream of claim 14 wherein said composition comprises from about 20 wt.% to about 36 wt.% pentafluoroethane.

29. The stream of claim 14 wherein said composition comprises from about 20

wt% to about 23 wt. % pentafluoroethane.

30. The stream of claim 14 wherein said composition consists essentially of 77 wt.

% 1,1,1,3,3-pentafluoroethane and 23 wt% pentafluoroethane.

31. The fog of claim 10 wherein said composition comprises from about 20 wt.%

to about 36 wt.% pentafluoroethane.

32. The method of claim 23 wherein said composition is contacted to said fire in

the form of a stream.