Flammable Materials

Flammable Materials, Organic Solvents, Corrosives, Explosives, Peroxide-Formers, Toxics

The basic safety issues relative to the chemical hazard classes noted above are discussed herein. For a specific chemical the Material Safety Data Sheet for the material should always be consulted. Electronic access to MSDS is available through the UCSB EH&S website.

i. Flammable Materials

Flammable and Combustible Liquids (Examples: alcohols, esters, ethers, ketones)

Vapors from flammable and combustible liquids can mix with air and burn if they contact an ignition source. Possible ignition sources include hot electrical wires, hot surfaces, open flames, hot particles and embers, and sparks. The lowest temperature at which a liquid releases enough vapor to start burning is called the flash point. The flash point is what distinguishes a flammable liquid from a combustible liquid.

Flammables: Liquids classified as flammable have flash points below 100 degrees Fahrenheit. At normal room temperature, flammable liquids are a much greater fire hazard than combustible liquids. Flammables include lacquer thinner, turpentine, acetone, ether, alcohol, gasoline, toluene and shellac. For example, ethyl ether (a common solvent) has a flash point (FP) of –49 deg. F and acetone has a FP of 0 deg. F.
Combustibles: These liquids have vapors which burn when heated above 100 deg. F. Combustibles include fuel oil, kerosene, mineral oil and paints.

Flammable Solids

Examples –
Organic Solids: camphor, cellulose nitrate and napthalene.
Inorganic Solids: decaborane, lithium amide, phosphorous heptasulfide, phosphorous sesquisulfide, potassium sulfide, anhydrous sodium sulfide and sulfur

Combustible Metals: (except dusts and powders): cesium, magnesium and zirconium, aluminum powder, calcium/magnesium/sodium metals.

Combustible Dusts/Powders:(including metals): finely divided flammable solids which may be dispersed in air as a dust cloud. Examples: wood sawdust, plastics, coal, flour and powdered metal (few exceptions).

Water Reactives: Sodium, potassium metal, certain metal hydrides such as lithium aluminum hydride and calcium hydride. Flammable solids are materials which burn so vigorously or persistently when ignited that a serious hazard is created. Flammable solids include finely divided solid materials which when dispersed in air as a cloud may be ignited and cause an explosion.

Pyrophorics (Examples: titanium dichloride, phosphorus, tributyl aluminum, dichlorosilane, organoboranes)

Pyrophorics are substances which present serious hazards due to their ability to ignite spontaneously upon contact with air. Accordingly, the use of these materials is specifically controlled by the CA Fire Code. Contact EH&S for review of new uses of pyrophorics.

• Store in air-tight containers in a dark, cool and dry place; label containers with receiving and opening dates, and dispose before expiration date.

• Yellow/white phosphorus should be stored and cut under water.

• The severe consequences of pyrophoric compounds mandate careful review of handling and storage procedures.

Guidelines for Safe Handling of Flammable and Combustible Materials

• Minimize the quantity of flammable materials on hand in operating areas, particularly in laboratories. Make it a habit to put flammables back in the flammable storage cabinet.

• Do not utilize flammable liquids on the bench top— use the fume hood.

• Label repackaged combustible and flammable materials as such

• Store flammable and combustible substances in closed metal safety cans or cabinets whenever possible.

• Store and use flammable materials away from electrical equipment, sources of static electricity, and machinery with moving parts.

• A maximum of (10) gallons of flammable liquids may be stored outside of a flammable storage cabinet, provided the following are observed:

• Quantities exceeding the above totals shall be stored in approved metal flammable liquid storage cabinets. Quantities stored in approved cabinets within labs or classrooms shall not exceed 60 gallons/cabinet and 120 gallons total.

• UCSB Policy 5460 prohibits smoking in any indoor area except a private residential space.

• Remove all obstructions which are blocking corridors and exits. Storage of any kind is not permitted within corridors.

• Never store anything in front of fire extinguishers or electrical panels.

• Become familiar with evacuation routes from the building, and know the Emergency Assembly Point for your building (generally posted on dept. Safety Bulletin Board).

• Know how to use and locate fire alarms, fire extinguishers, and cut-offs for electricity to work areas. EH&S offers a hands-on fire extinguisher class.

• Report any problems with accumulation of stored materials, locked or blocked exits, or other fire-related problems to your supervisor. Supervisors should contact the campus Fire Marshal at x3008.

• Utilize secondary containment for large containers to prevent the spread of spills

• Electrically ground all containers involved when pumping flammable liquids to prevent the buildup of static electricity.

ii. Organic Solvents

Examples: aromatic hydrocarbons, aliphatic hydrocarbons, freons, alcohols, ethers, ketones

Hazard Properties:

• Repeated skin contact with a solvent can cause the skin’s protective fats and oils to dissolve, resulting in reddening, itching, blistering, and pain.

• Some solvents can also be readily absorbed through the skin, producing systemic toxic effects.

• In addition to irritation of the respiratory tract and mucous membranes, inhalation can cause dizziness, drowsiness, headache, lack of coordination and nausea.

• Exposure over a prolonged period of time may result in damage to the liver, kidneys, lungs, blood, nervous system, and other organs. Carcinogenic, mutagenic and teratogenic effects are not uncommon.

• Many solvents are flammable; see Flammables above.

Practices:

• See Guidelines for Safe Handling of Flammable and Combustible Materials above.

• Use fume hoods to prevent inhalation of solvent vapors and build-up of flammable levels of vapor.

• Allow space for thermal expansion in all containers; overfilling can cause leakage or breakage. Glass bottles can rupture if they are filled nearly to the top with cold liquid and then stored in a warm area.

• Wear eye protection for all operations in which accidental splashing might occur.

• Substitute a less toxic solvent whenever possible.

• Avoid direct skin contact by using lab coat and solvent-resistant gloves and changing them whenever necessary.

• Use appropriate equipment to avoid ignition (e.g., flammable-storage refrigerators).

Specific Classes of Solvents—

Chlorinated Solvents

Examples: methylene chloride, chloroform, trichloroethylene

• Most of these compounds have an anesthetic or narcotic effect, causing people to feel intoxicated if overexposed. This can be particularly dangerous when working around machinery, as judgment and coordination can be impaired. Examples of compounds which are powerful anesthetics are trichloroethylene, ethylene dichloride, and chloroform.

• In studies on laboratory animals, several chlorinated hydrocarbons have been linked to the development of cancer in animals; examples of these compounds are: chloroform, perchloroethylene, and methylene chloride.

• Some of the chlorinated solvents are strong systemic poisons which damage the liver, kidneys, nervous system, and other organ system. These symptoms most often appear gradually, with nausea, loss of appetite, vomiting, headaches, weakness, and mental confusion most common. Carbon tetrachloride, tetrachloroethane, and 1,1,2-trichloroethane are examples of compounds which can cause systemic toxic effects.

• All chlorinated solvents can cause dermatitis (chapping, drying, rashes) on repeated contact with the skin, since they remove the protective fats and oils. Impervious gloves made of synthetic rubber can be worn for hand protection.

• Many of the compounds are highly irritating to the membranes around the eyes, and in the nose, throat, and lungs. Examples of chlorinated solvents which have irritant properties are ethylene dichloride and chloroform.

• When excessively heated, chlorinated solvents can decompose, forming highly toxic fumes such as phosgene, hydrochloric acid, and chlorine.

• With few exceptions, most of the chlorinated hydrocarbons are non-flammable.

Fluorinated Solvents (freons)

• Fluorocarbon solvents are organic compounds containing fluorine. The vapors are four to five times heavier then air and tend to accumulate in low places. This displaces the oxygen which can cause suffocation, or the vapors themselves may be toxic in high concentrations.

• Fluorocarbon solvents can dissolve the natural oils present in the skin, causing dryness and cracking with prolonged contact. Gloves made of neoprene or the equivalent should be worn when there is the possibility of prolonged or repeated skin contact with the liquid.

• Fluorocarbon vapors decompose when exposed to high temperatures. Toxic fumes such as hydrofluoric acid, hydrochloric acid, and phosgene may be formed. Therefore, it is advisable to avoid contact with hot surfaces, electric heating elements or open flames when working with freons.

• Fluorocarbon solvents are non-flammable.

• Since many fluorocarbons released into the air contribute to depletion of the ozone layer, evaporation should be kept to a minimum.

Aromatic Hydrocarbons (Examples: benzene, toluene, xylenes)

• Chronic exposure to a low concentration of benzene may damage the bone marrow, with resultant changes in blood cells. Benzene is considered carcinogenic, and has a relatively short latency period. Substitutes for benzene should be used.

• Aromatic hydrocarbon solvents defat the skin, and prolonged use causes drying, scaling and cracking. Many are also readily absorbed through intact skin and may produce systemic toxic effects.

• Splashing aromatic hydrocarbons into the eyes causes itching, tearing, and irritation, with injury to tissue after prolonged contact.

Aliphatic Hydrocarbons (Examples: hexanes, pentanes)

• Typically lighter aliphatic hydrocarbons (five to nine carbon atoms) are highly volatile and flammable with low flash points.

• Like routes of exposure are vapor for the lighter aliphatics and skin for the heavier aliphatics.

• Although not typically very toxic, the aliphatic hydrocarbons do cause many of the common symptoms related to organic solvent overexposure.

• N-hexane is unusual among aliphatic hydrocarbons as it is particularly toxic to the peripheral nervous system.

Ketones and Aldehydes (Examples: acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetaldehyde)

• These chemicals are generally highly flammable.

• Typical effects are those of respiratory tract irritation, anesthesia, and dermatitis.

Ethers (Examples: ethyl ether, dioxane, glycol ethers)

• Some ethers may cause anesthetic effects and may be potent irritants and cause dermatitis.

• Glycol ethers may, in addition to the typical symptoms of organic solvent overexposure, cause anemia (low red blood cell count) and have deleterious reproductive effects.

• The lower molecular weight ethers (e.g., diethyl ether) are highly volatile and are particularly hazardous flammable liquids.

• Many ethers can also form explosive peroxides upon exposure to air (see peroxide formers in this section).

iii. Corrosives

Examples:
Acids –   Solids: benzoic acid, sulfamic acid; Liquids: acetic acid, nitric acid, phenol, sulfuric acid; Gases: hydrogen chloride, hydrogen fluoride, hydrogen bromide, chlorine, and sulfur dioxide

Bases -   Solids: sodium, potassium and calcium hydroxides; Liquids: ammonium hydroxide, bromine; Gases: ammonia

Hazard Properties:

• Corrosives can seriously burn body tissue on contact as well as cause dermatitis and eye damage.

• Exposure to vapors or mists can affect the respiratory tract and mucous membranes.

• Corrosives are not flammable, but they can react with each other and with other chemicals, causing potential fire and explosion.

• Contact with ordinary materials such as paper and wood may generate sufficient heat to ignite; especially true for oxidzing acids such as nitric and perchloric.

• Many corrosives may cause delayed injury, particularly bases. The absence of immediate symptoms may prolong exposure and as a result, cause even more severe injuries.

Practices:

• Be aware of the nearest eyewash station and emergency shower. If a chemical splash occurs, flush immediately with running water for at least 15 minutes and seek medical attention.

• Use chemical splash goggles or other eye protection when working with acids/bases. Appropriate acid- and base- resistant protective clothing, including aprons, lab coats, and gloves, should also be worn.

• When diluting acids or bases with water, always pour the reagent slowly (while mixing) into the water, never the reverse.

• Always read labels and observe special precautions when handling corrosives.

• Whenever acid, base or solvent bottles are carried from the laboratory, the bottles should be placed in heavy duty buckets which act as secondary protective containers.

iv. Explosives

Examples: acetylides, azides, organic nitrates, nitro compounds, many peroxides, and perchlorates (e.g., ammonium perchlorate, picric acid, lead azide)

These compounds are unstable and may decompose spontaneously or through contact with the immediate environment. Protect these substances from shock, elevated temperature, rapid temperature changes and other reactive chemicals.

Some materials, such as lead azide, are regulated explosives. This means it is illegal to own, possess or create them in a laboratory without a permit from the appropriate agency. If you have need to use or create any potentially explosive compound determine the restrictions placed on it from your supervisor and the EH&S Campus Fire Marshal (x3008) prior to any work.

Keep in mind that a serious explosion from even milligram quantities can drive small fragments of glass or other matter deep into the body.

Practices:

• Serious consideration should be given to any experiment involving explosives so that any special safety measures and handling techniques are understood and followed by all persons involved. A written Standard Operating Procedures should be developed and rigorously followed.

• Only the smallest quantities adequate for the experiment being conducted should be present.

• Careful segregation from other materials must be performed.

• Special personal protection equipment (e.g., gloves, clothing, face shields) and engineering controls (e.g., barriers, remote access tools) may be required.

• Warning signs should be posted to read “DANGER: AUTHORIZED PERSONNEL ONLY”.

v. Peroxide Formers (see also Peroxides)

Examples: ethers, compounds with benzylic hydrogen atoms, aldehydes and many alkenes (e.g., cyclooctrene, diethyl ether, tetrahydrofuran, potassium metal, tetralin (tetrahydronapththalene))

• Over a period of time, these chemicals can generate levels of peroxides that may explode when the cap is removed, or when they are concentrated during distillation.

• If precipitate (crystals around the cap) or oily layer appear, do not open or use the material — call EH&S for disposal (x3293).

• Use a shield when evaporating or distilling mixtures which may contain peroxidizable compounds; chemical splash goggles or a face shield should also be worn.

• There are procedures for testing for presence of peroxides, including test-strips that are commercially available.

• Solutions of peroxides in volatile solvents should not be used under conditions in which the solvent might be vaporized due to the resulting increase in the peroxide concentration.

• Peroxide contamination by metals can lead to explosive decomposition; metal spatulas should not be used to handle peroxides.

• Avoid friction, grinding and all forms of impact near peroxides (especially solids).

• By storing peroxides at the lowest possible temperature, but above solubility or freezing point, the rate of decomposition is minimized.

• Spills of solutions of peroxides should be cleaned up immediately and absorbed on vermiculite.

• Special methods must be used to dispose of peroxides. Pure peroxides are never to be disposed of directly. Contact EH&S (x3293) for assistance.

vi. Toxics (see also the “ Basic Toxicology” section of this website)

All chemicals should be considered toxic to some degree and should be handled with caution. The level of toxicity (high, low, moderate) is based on dose-response measurements as performed on test animals. The term “toxic”, however must reference the route of entry for the material: inhalation, ingestion, skin contact, etc.    Lists of materials which are classified as acutely (highly) toxic are available electronically. All of these materials should be handled with special attention to appropriate engineering controls, personal protective equipment and general work practices.

The OSHA Laboratory Safety Standard stipulates that special provisions such as Standard Operating Procedures be included in a lab’s Chemical Hygiene Plan for the handling of these acutely toxic materials as well as for recognized chemical carcinogens and reproductive toxins. Development of SOPs is the responsibility of the laboratory supervisor Contact EH&S at x-4899 for questions regarding development of your Chemical Hygiene Plan.