DE1187489B - Halon fire extinguishers - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

A62d

German class: 61b-2

Number: 1187489

File number: N 23093 VI b / 61 b

Filing date: April 25, 1963

Opening day: February 18, 1965

Proposals are known to use the Tetrac carbon dioxide either because of its toxicity or by other less toxic © halogenated hydrocarbons! to replace with good fire-extinguishing effect or to use mixed with these. It was assumed here, that an increased number of hemi-genic atoms in the molecule should generally ensure better extinguishing effectiveness and, above all, greater security against reignition. Hydrocarbons containing chlorine and bromine, such as chloromethane, have a better extinguishing power than those containing chlorine and fluorine, such as triomorofluoromethane, trifluorobromomethane or dibromodofluoromethane, but their extinguishing power is less than that of carbon tetrachloride. In addition, the boiling points and vapor pressures of the halon extinguishing agents mentioned are very low. Mixtures of two components with different boiling points showed better extinguishing effectiveness compared to the individual components. Thus, for example chlorine and fluorine-containing compounds having boiling points of not more than +35 ⁰ C in an amount .of 20 were up. 50% together with other extinguishing liquids known for fire fighting, such as chlorobromomethane, used successfully to fight fires of liquid or gaseous fuels.

To evaporate the carbon tetrachloride too quickly to prevent this, as is well known, one has to use higher-boiling liquids or solid chlorinated hydrocarbons, such as hexachloroethane, perchlorinated naphthalene, perchlorinated diphenyl, perehlortriphenylbenzene and hexachlorobenzene and brominated halogen derivatives of methane and ethane, mixed. Such mixtures have the Disadvantage that these chlorine-containing additives in the brominated halogen derivatives of methane or ethane and are only sparingly soluble in carbon tetrachloride. Solvents added to overcome this disadvantage act too strongly diluting, which considerably reduces the extinguishing power of the mixture will. Solutions of incombustible chlorination products from chlorinated paraffins or paraffin mixtures with a chlorine content of at least 40 to 45% and at least such a high molecular weight, that they are normally no longer gaseous in bromine-containing halogen compounds of methane and / or ethane, on the other hand, should be used to combat ember fires, in particular from smoldering dusts, have proven their worth.

The study of behavior, of liquid, simply halogenated hydrocarbons up to 3 carbon atoms compared with different ones Halon fire extinguishing agents

Applicant:

Nu-Swift International Limited, Eiland,

Yorkshire (UK)

Representative:

Dr.-Ing. J. Schmidt, patent attorney,

Munich 2, Hermann-Sack-Str. 2

Named as inventor:

Sidney Bernard Anderton, Islet, Yorkshire

(Great Britain)

Claimed priority:

Great Britain May 30, 1962 (20775)

Fuels generated fires revealed that only these simply chlorinated hydrocarbons had extinguishing power because they are flammable from 4 carbon atoms. The compounds are simply chlorinated but already from 1 carbon atom, flammable. The extinguishing power, however, increases from the iodine to the Bromine to the chlorine compounds. As. The main carriers of the extinguishing effect were those under the influence the heat split off halogen elements determined. For the intensity of the extinguishing effectiveness of such Liquids are also the evaporation rate, the flow rate, the size of the flammable Hydrocarbon residue, the calorific value and the flavor size the burning liquid or the concentration of volatile, flammable components of the burning substance and the jet cone angle depending on the viscosity of the liquid extinguishing agent used authoritative.

The same investigations were carried out with multiple or mixed halogenated hydrocarbons carried out and found that this has an increased extinguishing effectiveness compared to the simple Have halogenated compounds, due to the increase in the number of halo atoms in the molecule such extinguishing agent. It was recognized here that the intensity of the extinguishing effectiveness is dependent of the rapidity of the disintegration of the multiply halogenated extinguishing agent increases, whereby multiply halogenated Methyl compounds act stronger than. the corresponding ethyl compounds. Best as a means

509 509/207

The dffluccdibrominethane was recognized as dissolving power, followed by Tefcrafluordibromätnan. It stays that way In addition, of decisive importance, what toxicity and corrosion effect that used Has halon solvent and the distance over which it can be thrown onto the flame (see Chemiker-Zeitung, Volume 81, No. 16, 1957, Pp. 526 to 531).

In these investigations, the polychlorinated methyl and ethyl compounds Dichloro- and TricMarmetnan, 1,1,2-Trichlor-, 1,1, 2,2-Tetraohlor- and Pentachloräthan with regard to their Viscosities, evaporation rates, flow rates, disintegration speeds, dissolving times and the consumed © Amount for extinguishing attempts against burning liquids in one. Distance of, 50 cm tested and found that dichloromethane has no extinguishing power and trichloromethane compared with Tetrachloride compound 25 to 30 «/» less extinguishing power possesses 1,1,2-trichloroethane decomposes within 1 to 2 seconds. The pyrolysis smoke consists of chlorine, a lot of hydrochloric acid and soot. '

In the end, these extensive tests show that there seems to be no such thing as a "universal extinguishing agent". Usually it wärdl SLCN ^*: therefore to extinguishing agent mixtures. act whose components are coordinated in such a way that the good effectiveness of the individual components while further containing their special disadvantages, such as high volatility, severe decomposition, excessive toxicity, corrosive effect, etc., is fully exploited.

The replacement of the high extinguishing effect of TeteacMorcarbones, which is relatively volatile and has too high toxicity, by .. Chlorobromomethane was an advance because the latter is less toxic and one; has at least the same extinguishing effectiveness as tetra-carbon. It is also less volatile. Therefore, Chlorbrommeftauiiim: Mixture 'with carbonic acid and, if necessary, small amounts of other halogen TcoMeawaesers & iiffiö especially against aircraft engine fires TMd Mixtures ams 50 bis. 80 parts by weight GhloibMominiEifhain ^; .tiind 20> -to: 50 parts by weight TriflEorbrommeiJxan recognized as particularly suitable against aircraft engine fires.

It has now been found that a liquid extinguishing agent, dos essentially l; l, l-trichloroethane, that KoMendfoxyd under pressure of about 3 to 20atü At the very least, the quenching efficiency of carbon tetrachloride is maintained. has »but is considerably less toxic than this *.,; although the 1,1,1-trichloroethane . alone is less dissolving than carbon tetrachloride and, in itself, carbon dioxide is only relatively small LöschwiifeuÄg ». .

• 1,1,1-Trichorethane is also considerably less toxic than 1,1,2-TriabutaräÄäB, which has already been investigated for its dissolving effectiveness, namely only about a fifth of its toxicity. It is only about half as toxic as chlorobromomethane and only about a twentieth as toxic as carbon tetrasound. !,!, l-Tricloroethane is also a relatively good solvent for carbon dioxide, so that it is homogeneous and saturated with the latter. Mixture (7 percent by volume CO ₂ ) in a fine spray jet leaves the fire extinguisher filled with it. While carbon dioxide pressures of 60 atmospheres were used with the known liquid halon fire-releasing agents, the pressures for the fire-extinguishing agent according to the invention were very low, namely between 3 and 20 atmospheres. The liquid jet has the correct strength within this pressure range, ie it is neither too coarse nor too fine. The carbon dioxide is not liquefied, but is dissolved in the liquid 1,1,1-trichloroethane.

To extinguish gasoline fires in a ^{closed space of around 70 m 3} , comparative tests with fire extinguishers carried out

a) carbon tetrachloride,

b) chlorobromomethane and

c) a mixture of 80% 1,1,1-trichloroethane and 20% chlorobromomethane

and which were each saturated with carbon dioxide under a pressure of 12 to 15 kg / cm ² , led to the finding that it was not possible in cases a) and b) after extinguishing the fires for more than 30 seconds in the Hold the fire room, while in case c) you only felt a slight discomfort after 5 minutes.

As already stated, this has 1,1,1-trichloroethane a lower extinguishing effectiveness than carbon tetrachloride, but it surpasses 1,1,2-trichloroethane Surprisingly significant as the latter is only of mediocre potency, though it has a higher boiling point (113 ° C compared to 74.1 ° C), so its evaporation rate is lower than that of the 1,1,1-isomer.

When used in a mixture with chlorobromomethane and carbon dioxide under pressure, the known good extinguishing power of the latter is achieved, however without! Increase in toxicity and the risk of corrosion.

The chloroboramethane content should not exceed Go beyond 50 percent by volume. For economic reasons, one does not use more than 10 to 20 percent by volume add chlorobromomethane, known per se as a halon extinguishing agent.

Claims (1)

Claim: Halon fire extinguishing agent improved by adding carbon dioxide under pressure, thereby characterized in that it consists essentially of 1,1,1-trichloroethane, the up to one Pressure of about 3 to 20 atmospheres of carbonic acid is added, if necessary with an addition of up to 50 percent by volume, especially 10 to 20 percent by volume, of the halon extinguishing agent component known chlorobromomethane. Considered publications:
German publications No. 1105 283,
1118 014; British Patent No. 691448;
Chemiker-Zeitung, 16/1957, pp. 526 to 531.