CHEMICAL DATA NOTEBOOK SERIES #68: FLUORINE
HAZARDOUS MATERIALS
Fluorine is a member of the family of elements known as halogens (other members are chlorine, bromine, iodine, and astatine, which is radioactive and very rare). Fluorine is a highly toxic, very corrosive, highly reactive, irritating, yellow gas with a choking odor. The most powerful oxidizer known, it is an extremely valuable chemical to industry. It is used principally to produce chemical compounds that contain the fluoride ion or the fluoride radical — that is, as a raw material to produce compounds such as fluorides for toothpaste and fluoridation of water, the monomers of fluorocarbons, and other compounds where the presence of fluorine in the compound is important to a chemical reaction. Fluorine may be shipped as a gas under pressure or as a cryogenic liquid. Its molecular formula is F2, and it has no synonyms.
PROPERTIES
Fluorine does not burn, but it vigorously supports combustion—better than oxygen or any other oxidizer. It has the following properties: vapor density 1.31, molecular weight 38, boiling point — 306.8°F, and freezing point — 363.4°F. Cryogenic liquid fluorine has a specific gravity of 1.108. Fluorine reacts with water to form a mixture of hydrogen fluoride, oxygen, ozone, hydrogen peroxide, and oxygen difluoride. All of these reaction products arc hazardous materials in their own right.
HAZARDS
Because fluorine is such a hazardous material, it is difficult to determine which of its properties is the most hazardous. Fluorine is such a powerful oxidizing agent that it actually oxidizes oxygen! The compound resulting from oxidation of oxygen is oxygen difluoride, OF2, also known as fluorine monoxide, fluorine oxide, or oxygen fluoride.
Fluorine’s presence with any material that will burn (any organic material and some metals) produces potentially explosive situations. Fluorine makes any ordinarily combustible material highly flammable and, in turn, makes any normally flammable material explosive. In other words, anything that will burn in air will burn hotter and faster when fluorine is present. If fluorine is present as a result of an accidental release, its enormous oxidizing power will be added to the oxidizing capability of the nearly 21 percent of the ambient atmosphere that is oxygen. If significant amounts of fluorine surround the fuel, an explosion may be imminent. It may be nearly impossible (and perhaps inadvisable) to extinguish a fire supported by leaking fluorine.
Oxidizers never should be stored near fuels (anything that will burn), and breaking this rule when fluorine is involved is more dangerous than doing so in the case of any other oxidizer. Preplanning inspectors must always keep this oxidizer-fuel restriction in mind during an inspection and see that violations of this rule arc corrected immediately.
When responding to an incident involving an accidental release of fluorine, the engine of an apparatus driven into or operated in an atmosphere containing some of the released fluorine (as would also occur near a spill of liquid fluorine) will be seriously damaged, perhaps even beyond repair. Any engine operating in such an atmosphere begins to race as the fluorine increases the burning speed of the fuel, and the resulting hydrofluoric acid that forms may seriously corrode the engine or its parts.
Fluorine causes severe lung damage when inhaled. A concentration of one percent fluorine in air kills in a few minutes, while 500 ppm (parts per million) has produced 100 percent fatalities in laboratory animals after exposure for one hour. Pulmonary irritation can occur at levels as low as two ppm, with greater damage occurring as the concentration in air increases. The ACGII1 (American Conference of Governmental Industrial Hygienists) has adopted a TLV-TWA (threshold limit value-time weighted average) of one ppm or 1.6 mg/m3 (milligrams per cubic meter), while OSHA has adopted an eight-hour timeweighted average of 0.1 ppm (0.16 mg/m3), The ACGIH has established the STEL (short-term exposure limit, usually for 15 minutes) at two ppm (or 3.1 mg/m3) and the 1DIJ1 (immediately dangerous to life and health) has been established at 25 ppm. The lowest concentration at which fluorine has been detected by smell is 0.035 ppm.
Fluorine is extremely corrosive to living tissue. Any contact of the gas with the skin can cause reactions ranging from simple irritation to severe burns, depending on the concentration of fluorine in the air. The burns will be comparable in appearance to thermal burns, with the added effects of chemical burns. Irreversible tissue damage can be expected in all but the lowest concentrations, such as levels near the TI.V-TWA. Any contact with the skin by liquid fluorine most likely will create irreversible tissue damage because of the extreme cold, and surrounding tissue will suffer severe chemical burns.
In very small quantities in the air, fluorine can be a respiratory irritant. Eye and skin irritation are also possible when the fluorine is in low concentration in the air, with the severity of the irritation increasing to skin burns as the concentration increases.
Fluorine is a highly reactive chemical and oxidizes all metals to the corresponding fluoride compound except certain metals used for containers. lines, and fittings. At least one reference lists such metals as nickel, copper. Monel, aluminum-siliconbronze alloy, and some special aluminums and stainless steels. Most other metals would be severely corroded by fluorine. Fluorine reacts violently (sometimes explosively) with many materials. Among the most common materials with which violent reactions are possible are ammonia, carbon, carbon monoxide, charcoal, halocarbons (such as carbon tetrachloride and chloroform), hydrobromic acid, hydrochloric acid, hvdrofluoric acid, hydriodic acid, hydrogen, hydrogen bromide, hydrogen chloride, hydrogen fluoride, hydrogen iodide, hydrogen sulfide, liquid hydrocarbons (such as gasoline and turpentine), most metals, metal iodides, nitric acid, oxygen, potassium perchlorate, potassium hydroxide, stainless steel, sulfur dioxide, water, and many other chemicals.
For economic reasons, fluorine may be shipped, stored, or used in a liquefied form. Fluorine’s boiling point is very low; the maximum temperature of the liquid will be at its boiling point, — 306.8°F. This means that at least two more hazards must be considered when in contact with liquid fluorine: the extreme coldness of the liquid and the tremendous vapor-toliquid ratio of 980 to 1. This means that one cubic foot of liquid fluorine will produce 980 cubic feet of gas at ambient temperature. In addition, liquid fluorine will flow on the ground, freezing everything it contacts, weakening or destroying everything it touches, and forming explosive mixtures with any combustible material with which it mixes.
NONFIRE RELEASE
Any accidental release of fluorine is hazardous, and all but the smallest releases should activate the local emergency plan as required by SARA Title III. This activation will notify all government agencies and other groups vital to a safe conclusion of the incident.
If compressed fluorine gas is leaking through a hole in its container, exercise great caution if considering an attempt to plug the leak. No organic materials such as wood, rubber, or plastic may be safe to use. Metals that can resist fluorine, such as those mentioned above, might be used. Contact the shipper of the fluorine to determine whether it is advisable to attempt to plug the leak. Highly fluorinated polymers such as PTFE (polytetrafluoroethylene, or Teflon® ) are resistant to fluorine.
Any leaking fluorine gas is cold, since lowering the pressure of the gas by releasing it from a container to atmospheric pressure causes the temperature to drop. This adds slightly to its vapor density (cold gases are more dense than warm gases). Since fluorine already is heavier than air, it sinks to the ground and flows along low spots. Since fluorine is not flammable, the normal danger of a gas finding an ignition source and “flashing” back to the source of the leak does not exist. However, barring a wind or breeze, the fluorine will flow and accumulate in enclosed spaces, producing a great toxic danger to anyone entering the area without respiratory protection. Eye and skin burns are also possible, depending on the concentration.
Another great hazard in areas where fluorine accumulates, in spite of its nonflammability, is the intensified burning of any combustible materials within the fluorine concentration, assuming there is an ignition source. So, instead of a flash back to the source of the leak, a very hot and fast-spreading fire is possible at the source of ignition rather than at the source of the leak.
Consider evacuation at the source of the leak immediately and carry it out downwind. Distances depend on the size of the container, and evacuation in a radius of one-half mile around the leak to one to two miles downwind may be sufficient.
Eliminate all ignition sources, and take other precautions standard for flammable, toxic, and corrosive gases. Approach the site from upwind; remember the damage that the gas can do to internal-combustion engines, not to mention unprotected emergency responders.
Prevent liquid fluorine from entering sewer systems and waterways. Any liquid fluorine entering a sewer has explosive potential due to the presence of organic material and the possible presence of methane, a byproduct of the anaerobic decomposition of organic matter. If fluorine enters a sewer, an explosive condition may exist throughout the underground system, needing only an ignition source to initiate it. Notify sewage-treatment facilities immediately.
Any liquid fluorine entering a stream or other body of water causes localized freezing of the water on contact. The liquid fluorine sinks in the water as it boils and reacts with it. Reaction with the water produces hydrogen fluoride gas (which dissolves in the water to form hydrofluoric acid), plus the other hazardous by-products mentioned earlier. Notify all downstream users of the water at once, and the environmental authorities will constantly monitor the contamination. Appropriate neutralizing agents may be added to the water to speed decontamination. Soda lime (a mixture of sodium hydroxide and calcium oxide, two very hazardous materials) is a possible neutralizing agent; sodium carbonate (baking powder) is much safer but less efficient. Consult manufacturers of the fluorine for the best neutralization techniques and materials. Environmental authorities will determine the amount of soil and water contamination and how much soil may have to be removed. Activated charcoal (or carbon) should not be used to adsorb fluorine, since an explosive reaction is possible when fluorine and carbon mix together.
Emergency responders, especially firefighters, should not perform cleanup activities. Professional salvage and cleanup companies have properly educated, trained, and equipped employees who can remove the hazardous material safely. Professional services are especially important in incidents involving fluorine, which has multiple hazards —all of them extremely dangerous.
FIRE SCENARIO
Should a container of fluorine be exposed to the radiant heat of a fire, it should be cooled by water applied by unmanned appliances from as great a distance as possible. If the containers are equipped with safety-relief devices that are operating, a deadly, corrosive, oxidizing gas will be forced out, creating a very hazardous situation for anyone nearby. Whenever fluorine contacts water, the fluorine may react with that water, forming and spreading other hazardous materials.
If die fire is very close or if flames are impinging on the container, the fire will be fed (supported) by the fluorine being released. This portion of the fire will be much hotter than other nearby flames, and the addition of an oxidizer generally will speed up the burning process.
If the vents are not operating, the pressure inside the container will rise until it surpasses the design strength of the container, and it will fail catastrophically, spewing shrapnel in addition to its contents.
If the container holds liquid fluorine, the heat may or may not be reaching the product inside because cryogenic liquids are kept in a container within a container, and the air space acts as an efficient insulator. Continued absorption of radiated heat, however, eventually will have some effect on the liquefied fluorine. As the inner container absorbs heat energy, the liquid boils, generating fluorine gas that will be vented to the outside. If water is used to try to cool this container (called a Dewar’s flask, or just plain Dewar), any water that contacts the tank near the vent freezes instantly, thus blocking the pressure-relief system. If threatened containers cannot be cooled safely and no life is threatened by the failure of the containers, withdrawal may be the preferred tactic.
No fire being fed by fluorine leaking from a container should be extinguished until the flow of fluorine can be stopped.
If fluorine may begin to leak again after the fire has been extinguished, it may be prudent to allow the fire to continue to burn until all the fluorine has been consumed, especially if no life is threatened.
Techniques that ordinarily would extinguish the burning fuel by removing the oxygen may not work in this instance, since additional oxidizer in the form of fluorine gas is being added. Other normal fire extinguishing techniques may not be effective because of the ferocity with which the fire will be burning.
PROTECTIVE CLOTHING AND EQUIPMENT
Choose protective clothing and equipment that prevent any contact of the fluorine with the eyes or skin. Rubber gloves, aprons, and boots may offer some limited skin protection; wear splashproof chemical goggles to protect the eyes. Use positive-pressure. self-contained breathing apparatus with frill face masks tor respiratory and eye protection. The face masks, unless made from highly fluorinated polymers, will offer protection for only a limited time.
Manufacturers of total encapsulating suits claim that suits made of neoprene may offer protection for a longer period of time. Contact the individual manufacturers of total encapsulating suits to inquire about the degree of safety offered by each recommended material; also consult the manufacturers of fluorine for their recommendations concerning the proper protection.
FIRST AID
Speed in removing the victim from the contaminated atmosphere is just as critical as removing the liquid or vapor from the victim’s eyes and skin.
Inhalation. The victim should be moved to fresh air, kept calm and warm, and be given 100 percent oxygen immediately. If oxygen is not immediately available and the victim’s breathing has stopped or becomes labored, artificial respiration should be administered; the first-aid giver must be aware that such action might expose him/her to the material in the victim’s lungs and/or vomit. Administering 100 percent oxygen immediately is critical and should be done while seeking immediate medical attention.
Eye contact. Flush the eyes immediately for at least 15 minutes, lifting the eyelids occasionally. Immediate medical attention is required.
Skin contact. Drench affected areas of the body with large amounts of water after removing the victim’s contaminated clothing. Immediate expert medical attention is needed to attend to the skin burns.
Ingestion. It is unlikely that anyone would ingest liquid fluorine.
