DE69011662T2 - Non-toxic fire extinguishing agent. - Google Patents

Description

The invention relates to non-toxic fire extinguishing agents and, in particular, to an agent that extinguishes a fire without producing toxic gases or compounds.

For many years, fire extinguishing technology has been designed to extinguish fires quickly, regardless of whether the substances produced during extinguishing are toxic to humans or harmful to the environment.

There has been little progress in fire extinguishing technology for 25 years. However, the use of effective and widely used fire extinguishing agents such as carbon tetrachloride or Halon 2402 has recently been increasingly and systematically banned. It has been proven that these substances have an immediate toxic effect. It is to be expected that further regulations will come into force in order to limit possible environmental damage caused by the few effective fire extinguishing agents that are still approved. There are currently no fire extinguishing agents, let alone any in use, that are effective and at the same time clean, non-toxic, harmless, non-corrosive and generally environmentally friendly.

Derek A. Thacker has conducted research into the development of effective fire extinguishing agents and fire retardants including non-toxic fire extinguishing agents. DA Thacker is named as inventor in GB-A-2185394 which discloses a fire extinguishing agent composition comprising at least one of trichlorofluoromethane, dichlorodifluoromethane, trichlorotrifluoroethane, dichlorotetrafluoroethane and a fire extinguishing agent carrier containing a sesquiterpene. This composition is said to be relatively non-toxic in both the unpyrolyzed and pyrolyzed forms due to the absence of bromine. Derek Thacker is also named as inventor in US-PS 4 908 160 which relates to a fire extinguishing agent composition containing ammonium and sodium hydrogen phosphate(s). Also in the prior art includes GB-A-1603867 which relates to a fire extinguishing composition comprising trichloromethane and a monoterpene-containing additive, which may further contain dichlorodifluoromethane.

The first aspect of the invention relates to the use of a terpene or unsaturated oil as a detoxifying agent in a fire extinguishing agent composition containing one or more fluorocarbons selected from trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane and 1,2-dichloro-2,2-difluoroethane.

The invention relates to a new fire extinguishing agent which consists of a group of compounds which, when combined, extinguish a fire without producing toxic gases. Chemical additives are used in the fire extinguishing agent to detoxify toxic combustion products produced by fire extinguishing agents contained in the composition by means of a rapid chemical reaction. These separately used fire extinguishing agents have been rejected by the approval authorities because they convert into toxic substances at higher temperatures due to chemical decomposition or damage the environment. The detoxifying agents according to the invention are food additives approved under Title XXI of the United States Food and Drug Administration.

According to the first aspect of the invention, the terpene can be selected from: citral, citronellal, citronellol, limonene, dipentene, menthol, terpinene, terpinolene, sylvestrene, sabinene, menthadiene, zingiberene, ocimene, myrcene, α-pinene, β-pinene, turpentine, camphor, phytol, vitamin A, abietic acid, squalene, lanosterol, saponin, oleanolic acid, lycopene, β-carotene, lutein, α-terpineol and p-cymene; and the unsaturated oil can be selected from: oleic, linoleic, linolenic, elaeostearic, lincanic, ricinoleic, palmitoleic, petroselic, vaccenic and erucic acid.

According to a second aspect of the invention there is provided a non-toxic fire extinguishing agent comprising in combination:

(a) at least one fluorocarbon selected from trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane and 1,2-dichloro-2,2,-difluoroethane

(b) an unsaturated oil selected from oleic, linoleic, linolenic, elaeostearic, lincanic, ricinoleic, palmitoleic, petroselinic, vaccenic and erucic acid.

The composition according to the first or second aspect of the invention may further contain at least one of the fluorocarbons of group c) which comprises: dichlorodifluoromethane, 1,2-dichlorotetrafluoroethane, chlorodifluoromethane, 1- chloro-1,2,2,2-tetrafluoroethane, pentafluoroethane, 1,2,2,2-tetrafluoroethane.

According to the first aspect of the invention, the non-toxic fire extinguishing agent preferably comprises:

(a) trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane or 1,2-dichloro-2,2-difluoroethane,

b) Dipentene or linoleic acid and

c) Dichlorodifluoromethane and 1,2-dichlorotetrafluoroethane.

According to a third aspect, there is provided a non-toxic fire extinguishing agent comprising:

a) at least one fluorocarbon selected from trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane and 1,2-dichloro-2,2-difluoroethane;

b) Dipenten and

c) dichlorodifluoromethane and/or 1,2-dichlorotetrafluoroethane.

The non-toxic fire extinguishing agent according to the third aspect of the invention may further comprise:

c') at least one of the following compounds: chlorodifluoromethane, 1-chloro-1,2,2,2-tetrafluoroethane, pentafluoroethane, 1,2,2,2-tetrafluoroethane.

Performance characteristics established for effective fire extinguishing may impose certain restrictions on the composition of the fire extinguishing agent:

1) Trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane or 1,2-dichloro-2,2-difluoroethane can contain at least 50 wt.%

2) the terpene or unsaturated oil may contain at least 2% but not more than 10% by weight,

3) the proportion of fluorocarbons of group c) according to the first and second aspects of the invention and of group c) or c) and c') according to the third aspect of the invention can amount to a maximum of 48% by weight, all proportions in each case based on the total amount of fire extinguishing agent.

The proportions chosen in each case, subject to restrictions regarding the type of compound and its mixture, are determined by the respective application technology, the material costs and the impact on the environment.

A special non-toxic fire extinguishing agent suitable for hand-held fire extinguishers has the following composition:

65% trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane or 1,2-dichloro-2,2-difluoroethane;

15% dichlorodifluoromethane;

15% 1,2-dichlorotetrafluoroethane;

5% Dipenten.

Another special non-toxic fire extinguishing agent has the following composition: 90% trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane or 1,2-dichloro-2,2-difluoroethane; 10% linoleic acid.

Fluorocarbons, such as those used as evaporating refrigerants, cause very little damage to the ozone layer compared to the approved brominated halon fire extinguishing agents, such as Halon 1211 or 1301 (trade names).

Many fluorocarbons have a remarkable fire-extinguishing effect on wood, hydrocarbon and electrical fires. They have very low toxicity, except when pyrolyzed at elevated temperatures. However, it has been demonstrated that fluorocarbons decompose in fire, producing primarily dangerous concentrations of hydrogen chloride and secondarily hydrogen fluoride, chlorine and fluorine.

The inventors have found that the problem of volatile chlorofluorocarbons, which produce dangerous compounds when ignited, can be eliminated by using a small amount of terpene or unsaturated oil in the chlorofluorocarbon fire extinguishing agent component. Although the inventors do not wish to be limited by theoretical considerations, they believe that the chemically active double bonds contained in the terpene or unsaturated oil will quickly neutralize the expected toxic gases by harmless chemical bonding. The inventors have carried out room-scale fire extinguishing tests using detoxified fluorocarbon mixtures at the British Columbia Research Council, Vancouver, Canada. It was shown that properly selected terpenes or unsaturated vegetable oils drastically reduce the expected concentrations of toxic hydrogen halides or halogens to levels that are less than 10% of the generally accepted "immediate danger to life and health (IDLH) concentrations". The carbonyl halide concentration generated was determined to be < 1 ppm (parts per million), a concentration that corresponds to that generated by water vapor in a typical fire.

The inventors have found three chlorofluorocarbons that are currently commercially available and that are suitable as fire extinguishing agents. One of these compounds is trichlorofluoromethane, which boils at 24ºC under normal pressure. It has Compared to other chlorofluorocarbons, it has a slow fire extinguishing effect, but has a longer range. Range is the distance that the fire extinguishing agent can cover in a fire without losing its fire extinguishing effect. Another of these compounds is 1,2-dichlorotetrafluoroethane, which boils at 4ºC under normal pressure, has a good fire extinguishing effect, but has a shorter range. The third of these compounds is dichlorodifluoromethane, which boils at -30ºC under normal pressure, has a good fire extinguishing effect and also has a scattering effect on the distribution pattern of the escaping fire extinguishing agent.

The inventors have found that the distribution pattern of the escaping fire extinguishing agent can change the fire extinguishing effect by a factor of 5. The inventors have developed fire extinguishing agent compositions containing chlorofluorocarbons that are optimally effective in a wide range of typical fires. The compositions preferably have a high trichlorofluoromethane content in order to prevent the reignition of extinguished fires.

The inventors have discovered that two specific detoxifying agents, namely dipentene and linoleic acid, are particularly effective in fire extinguishing compositions. Dipentene, a natural product found in the peels of citrus fruits, is non-toxic, highly volatile, soluble in fluorocarbon compositions and has been found to be an effective agent for binding and detoxifying undesirable toxic combustion products. Linoleic acid, the main constituent of sunflower and safflower edible oil, is non-toxic, soluble in chlorofluorocarbon mixtures which are of interest as fire extinguishing agents according to the invention and has been found in the tests carried out by the inventors to be an effective agent for binding and detoxifying undesirable toxic combustion products. However, unlike dipentene, linoleic acid is not very volatile and it has been found that after a small residue remains after the fire extinguishing agent evaporates. However, since linoleic acid is less volatile than dipentene, it has the advantage of increasing the range of the fire extinguishing agent up to 100 meters. It can therefore be concluded that linoleic acid is best suited for use in fire extinguishing agents for extinguishing fires outdoors, while dipentene, due to its higher volatility and lack of residue, is best suited for use in fire extinguishing agents for extinguishing fires indoors.

The invention is explained in more detail using the following examples.

example 1 Ineffective fire extinguishing agent

The Underwriters Laboratories of Canada and the USA have established performance criteria for acceptable fire extinguishing agents. One of the simplest criteria is the 1B test, which involves placing 12.5 liters of n-heptane in a 0.23 m² (2.5 square foot) pan and waiting for the maximum rate of fire to occur. An agent that extinguishes this 1B fire would receive a 1B classification, while an agent that extinguishes an n-heptane fire twice the size would receive a 2B classification, and so on.

In comparison to Example 2 below, a commercially available fire extinguishing agent containing Halon 1211 with a ULC 2B classification was used on a fully developed 1B fire outdoors. A passive "back-off" technique was used. It was found that this 2B unit failed to extinguish the 1B fire due to the passive back-off technique used by the operator and the presence of a slight air movement at a speed between 8.05 and 11.27 km/h (5 - 7 miles/h).

Example 2

The following fire extinguishing agent formulation has been proven to have good fire extinguishing properties without producing toxic combustion by-products. For easy identification, the formulation is referred to as NAF interior mixture (trademark NAF). It has the following composition (in % by weight):

65% fluorotrichloromethane,

15% dichlorodifluoromethane,

15% 1,2-dichlorotetrafluoroethane,

5% Dipenten.

This NAF indoor mixture has been shown to be effective in extinguishing wood and hydrocarbon fuelled fires, including n-heptane, using portable hand-held fire extinguishers, as well as in extinguishing electrical fires. The NAF indoor mixture has also been shown to be effective in automatic sprinkler and flooding systems. At room temperature, the four components are miscible and chemically inert to one another. Furthermore, they do not corrode typical metal containers.

In a typical performance test conducted by technicians at Underwriters Laboratories in Canada [0.23m2 (2.5 square feet) ULC-1B test], 367 ml (532 g) of the mixture extinguished 12.5 L of burning n-heptane in 1.9 s. This result was achieved using a passive back-off technique, as would normally be used by an inexperienced firefighter. An aggressive technique, as permitted by Underwriters Laboratories testing methods, was not required. The smoke observed was minimal and did not obstruct the view of the fire, the extinguishing stream or the escape route.

Similar results (see Example 3 below) were obtained in standard wood fires (ULC-1A test) as well as in fires caused by automatic flooding/sprinkler systems were extinguished.

This mixture proved to be a safe electrical insulator at 150 kV in tests carried out at Imperial College.

Physical properties of the NAF interior mixture

Toxicity 350 000 ppm, 30 min, 50% lethal;

observed boiling point: 10ºC (50ºF);

Density (10ºC): 1.44 g/ml;

Evaporation rate: 3.4 mg/cm²/s Temperature Vapor pressure ATM [bar]

Example 3

A wood fire was set up in accordance with U.S. Underwriters Laboratories specifications, consisting of 10 layers of dry logs measuring 2 x 2 x 20 in3 (5.08 x 5.08 x 50.8 cm3), with 5 logs in each layer. The setup was ignited using n-heptane and allowed to burn for 8 minutes to ensure that the fire was fully developed and had "eaten" deep into the stack. An agent that would extinguish this fire would receive a 1A classification, while agents that extinguish larger wood fires of similar configuration would receive a higher classification.

By applying 500 g of NAF interior mixture to three side surfaces and the top of the 1A wood fire, the fire was extinguished in less than 5 s.

Example 4

The following fire extinguishing agent composition showed good fire extinguishing effect without producing toxic combustion byproducts. For easy identification, the mixture is called NAF outdoor mixture.

The NAF outdoor mixture (trademark: BLITZ) has the following composition (in % by weight):

90% Fluorotrichloromethane

10% linoleic acid.

The mixture has proven effective when used on large outdoor fires where water should not be used and the extent of the fire requires a range of between approximately 10 and 100m. At these higher ranges, dichlorodifluoromethane is not desirable as it leads to a wider spread of the extinguishing jet, thereby reducing the fire extinguishing effect. In these cases, a higher proportion of linoleic acid is preferably used to avoid excessive broadening of the extinguishing jet.

A performance test of this mixture was conducted at the Transport Canada Training Institute at Abbotsford Airport, British Columbia, under the supervision of a large group of government and institute personnel. Approximately 2000 liters of jet fuel was placed in a 15.24 x 30.84 m² (50 x 100 square foot) shallow burning pit partially filled with natural rainwater. The jet fuel was ignited and the maximum burn rate was allowed to reach. A helicopter hovering about 50 m above the fire in a downwind direction released 400 liters of NAF outside mixture, which spread in the fall to cover almost the entire downwind edge of the burning pit. The opaque vapor cloud was observed to locally extinguish the fire as it passed over the fire pit. After 10 s, the isolated residual flames along the downwind edge of the fire pit were extinguished with a single 2 kg NAF The fire was extinguished using a hand-held fire extinguisher containing an outdoor mixture. The wind speed was between 9.3 and 18.5 km/h (5 - 10 knots). Attempts to deliberately reignite the unburned fuel in the pit failed for several minutes.

Environmental damage to scale models conducted outdoors prior to the above-described test showed that a mixture of five parts gasoline and one part NAF outdoor mix cannot be set on fire with matches.

Physical properties of the NAF outdoor mixture

Toxicity 330 000 ppm, 30 min, 50% lethal;

observed boiling point: 27ºC (81ºF);

Density: 1.46 g/ml;

Evaporation rate: 1.5 mg/cm²/s Temperature Vapor pressure ATM [bar]

Alternative formulations

The two NAF mixtures disclosed here (NAF and BLITZ) have less impact on the ozone layer than conventional halon fire extinguishing agents, as can be seen from the following comparison: Fire extinguishing agent Ozone depletion NAF BLITZ Halon Malon

Nevertheless, the NAF fire extinguishing agents can be reduced to ozone depletion values of < 0.05 by replacing the chlorofluorocarbons listed in Examples 2, 3 and 4 above with the following chlorofluorocarbons. Name Boiling point [ºC] Ozone depletion Chlorodifluoromethane 1,1-dichloro-2,2,2-trifluoroethane 1-chloro-1,2,2,2-tetrafluoroethane Pentafluoroethane 1,2-dichloro-2,2-difluoroethane 1,2,2,2-tetrafluoroethane

With the sole exception of chlorodifluoromethane, none of these chlorofluorocarbons were produced on a commercial scale in 1988. Therefore, the two formulations listed above are preferred solely on the basis of availability and economics. Dipentene and linoleic acid are also the preferred detoxifying agents. However, a list of acceptable substitutes for these two agents is given below. It includes almost all of the terpenes normally obtained from plant material by steam distillation, as well as most of the unsaturated fats and oils obtainable from natural sources:

TERPENES UNSATURATED OILS

Citral Oleic Acid

Citronellal Linoleic Acid

Citronellol Linolenic acid

Limonene Elaeostearic acid

Dipentene Lincanic acid

Menthol Ricinoleic Acid

Terpinene Palmitoleic acid

Terpinolene Petroselinic acid

Sylvestrene Vaccenic Acid

Sabinene Erucic Acid

Menthadien

Zingiberen

Ocimen

Myrcen

α-Pinene

β-Pinene

turpentine

Camphor

Phytol

Vitamin A

Abietic acid

Squalen

Lanosterol

Saponins

Oleanolic acid

Lycopen

β-carotene

Lutein

α-Terpineol

p-Cymene

Of course, the possible variations in the basic formulation of NAF fire extinguishing agents are innumerable. Nevertheless, all effective variations must generally comply with the basic principles of the invention. In order to obtain the most effective fire extinguishing agent, the formulation must meet the following conditions:

(1) The detoxifying agent, dipentene, linoleic acid or the substitutes listed above, must be present in a concentration of at least 2% by weight of the total amount of the formulation in order to achieve chemical detoxification of the chlorofluorocarbon. On the other hand, the proportion of these additives must not exceed 10% by weight of the total amount of the formulation without impairing the fire-extinguishing effect of the resulting mixture.

(2) The proportion of higher boiling chlorofluorocarbons, such as fluorotrichloromethane, 1,2-dichloro-2,2-difluoroethane and/or 1,1-dichloro-2,2,2-trifluoroethane, alone or in combination, in a formulation must be at least 50% by weight of the resulting mixture. The use of higher boiling components in this order of magnitude prevents the fire from flashing back.

(3) The proportion of low-boiling chlorofluorocarbons or fluorocarbons such as dichlorodifluoromethane, 1,2-dichlorotetrafluoroethane, 1-chloro-1,2,2,2-tetrafluoroethane, 1,2,2,2-tetrafluoroethane, chlorodifluoromethane and/or pentafluoroethane, alone or in combination, must not exceed 48% by weight of the resulting mixture. Low-boiling components cause a wider distribution and a faster effect of the fire extinguishing agent over short distances in hand-held fire extinguishers, but have the disadvantage of a reduced range.

Claims (20)

1. Use of a terpene or unsaturated oil as a detoxifying agent in a fire extinguishing agent composition containing one or more fluorocarbons, selected from trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane and 1,2-dichloro-2,2-difluoroethane. 2. Use according to claim 1, wherein the terpene is selected from citral, citronellal, citronellol, limonene, dipentene, menthol, terpinene, terpinolene, sylvestrene, sabinene, menthadiene, zingiberene, ocimene, myrcene, α-pinene, β-pinene, turpentine, camphor, phytol, vitamin A, abietic acid, squalene, lanosterol, saponin, oleanolic acid, lycopene, β-carotene, lutein, α-terpineol and p-cymene; and the unsaturated oil is selected from oleic, linoleic, linolenic, elaeostearic, lincanic, ricinoleic, palmitoleic, petroselic, vaccenic and erucic acid. 3. Use according to claim 1 or 2, wherein trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane or 1,2-dichloro- 2,2-difluoroethane makes up at least 50% by weight of the total extinguishing agent. 4. Use according to claim 1, 2 or 3, wherein the terpene or the unsaturated oil constitutes at least 2% but not more than 10% by weight of the total extinguishing agent. 5. Use according to claim 2, 3 or 4, wherein the extinguishing agent contains 90% by weight of trichlorofluoromethane, 1,1-dichloro-2,2,2- trifluoroethane or 1,2-dichloro-2,2-difluoroethane and 10% by weight of linoleic acid. 6. Use according to claim 1, 2, 3 or 4, wherein the extinguishing agent contains one or more fluorocarbons selected from the group a) with dichlorodifluoromethane, 1,2-Dichlorotetrafluoroethane, chlorodifluoromethane, 1-chloro- 1,2,2,2-tetrafluoroethane, pentafluoroethane, 1,2,2,2-tetrafluoroethane. 7. Use according to claim 6, wherein the compound(s) of group a) make up (make up) not more than 48% by weight of the total extinguishing agent. 8. Use according to claim 6 or 7, wherein a) trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane or 1,2- dichloro-2,2-difluoroethane make up at least 50% by weight; b) the compound(s) of group a) make up a maximum of 48% by weight and c) the terpene or the unsaturated oil make up at least 2% but not more than 10% by weight of the entire extinguishing agent. 9. Use according to claim 6, 7 or 8, wherein the extinguishing agent contains: a) trichlorofluoromethane, 1,1-dichloro-2,2,2- trifluoroethane or 1,2-dichloro-2,2-difluoroethane, b) dipentene or linoleic acid and c) dichlorodifluoromethane and 1,2-dichlorotetrafluoroethane. 10. Use according to claim 6, 7, 8 or 9, wherein the extinguishing agent contains: 65% by weight of trichlorofluoromethane, 1,1-dichloro- 2,2,2-trifluoroethane or 1,2-dichloro-2,2-difluoroethane; 15% by weight of dichlorodifluoromethane; 15% by weight of 1,2-dichlorotetrafluoroethane; and 5% by weight of dipentene. 11. Non-toxic fire extinguishing agent containing in combination: (a) at least one fluorocarbon selected from trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane and 1,2-dichloro-2,2, difluoroethane and (b) an unsaturated oil selected from oleic, linoleic, linolenic, elaeostearic, lincanic, ricinoleic, palmitoleic, petroselinic, vaccenic and erucic acid. 12. Non-toxic fire extinguishing agent according to claim 11, wherein the compound(s) of group a) make up at least 50% by weight of the total extinguishing agent. 13. Non-toxic fire extinguishing agent according to claim 11 or 12, wherein the unsaturated oil from group b) makes up at least 2 wt.%, but not more than 10 wt.% of the total extinguishing agent. 14. A non-toxic fire extinguishing agent according to claim 11, 12 or 13, which contains 90 wt.% trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane or 1,2-dichloro-2,2-difluoroethane and 10 wt.% linoleic acid. 15. Non-toxic fire extinguishing agent according to claim 11, 12 or 13, which further contains one or more compounds, selected from the group c) with dichlorodifluoromethane, 1,2-dichlorotetrafluoroethane, chlorodifluoromethane, 1-chloro- 1,2,2,2-tetrafluoroethane, pentafluoroethane, 1,2,2,2-tetrafluoroethane. 16. Non-toxic fire extinguishing agent containing: a) one or more fluorocarbons selected from trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane and 1,2-dichloro-2,2-difluoroethane; b) dipentene and c) dichlorodifluoromethane and/or 1,2-dichlorotetrafluoroethane. 17. Non-toxic fire extinguishing agent according to claim 16, which additionally contains at least one or more compounds from group c') with chlorodifluoromethane, 1-chloro-1,2,2,2-tetrafluoroethane, pentafluoroethane, 1,2,2,2-tetrafluoroethane. 18. Non-toxic fire extinguishing agent according to claim 16 or 17, wherein the compounds of group c) or c) and c') make up no more than 48% by weight of the entire extinguishing agent. 19. Non-toxic fire extinguishing agent according to claim 16, 17, 18, wherein a) the compound(s) of group a) make up at least 50% by weight of the entire extinguishing agent; b) the compound(s) of group c) or c) and c') make up no more than 48% by weight of the entire extinguishing agent; and c) the dipentene makes up at least 2% by weight and no more than 10% by weight of the entire extinguishing agent. 20. Non-toxic fire extinguishing agent according to claims 16, 17, 18 or 19, which contains: 65% by weight of trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane or 1,2-dichloro-2,2-difluoroethane; 15% by weight of dichlorodifluoromethane; 15% by weight of dichlorotetrafluoroethane and 5% by weight of dipentene.