Chemical Data Notebook Series #16: Methanol
FEATURES
HAZARDOUS MATERIALS
Moonshiners” have used methyl alcohol, or methanol, for years. Because it has a taste similar to that of ethyl alcohol (the alcohol in alcoholic beverages), it’s sometimes added to illegally fermented “moonshine” to increase the volume.
But methyl alcohol is no drink. It’s a chemical poison that interrupts vital nerve impulses. Consumption of ¼ ounce or more may be fatal. And, if quantities less than a fatal amount are ingested, the material attacks the optic nerve, causing blindness.
Fire managers face problems other than ingestion. Methyl alcohol is flammable and produces vapors that, if allowed to accumu-late, could produce an explosion when ignited. And because it burns somewhat “cleanly,” its pale blue flame may be difficult to see in bright sunlight. Thus firefighters and victims may be covered by flames and not realize it— which, of course, can prove fatal.
Editor’s note: This series, covering the 100 to 150 chemicals which represent 95 percent of the volume of chemicals transported and used in this country, began more than a year ago. We said at the time that we hoped fire departments would use the information in preparing their own hazardous-materials reference guides in order to have the full range of information available in one place.
To assist in this effort, we’re reprinting the single-page, blank haz-mat data sheet that accompanied the first article (see page 65). You can copy this sheet and fill in the information after studying each chemical, then file it in a loose-leaf binder.
At the suggestion of a reader, we’re also adding a further aid to compiling your own reference binder, by numbering each article as it appears. You may want to go back to the previous articles you’ve saved and number them accordingly:
- Sulfuric acid, June 1986
- Chlorine, July 1986
- Vinyl chlorine, August 1986
- Ammonium nitrate, September 1986
- Nitric acid, October 1986
- Oxygen, November 1986
- Ethylene oxide, December 1986
- Sodium hydroxide, January 1987
- Hydrogen peroxide, February 1987
- Ammonia, March 1987
- Acrylonitrile, April 1987
- Calcium carbide, May 1987
- Acetone, June 1987
- Hydrocyanic acid, July 1987
- Ethylene, August 1987
Methyl alcohol is a clear, colorless liquid with the sweet and pungent odor of alcohol. It’s used in the manufacture of many materials, including plastics, coatings, dyes, and soaps. It’s also a major ingredient in some antifreezes, inks, paint removers, and cleaning products, as well as a solvent for many materials. In 1985, methyl alcohol was the 22nd highest-volume chemical in the United States.
The substance has a flash point of 54° F, making it a hazard at room temperature. And its ignition temperature of 725° F is attainable by all common ignition sources. Its flammable range is from 6% to 36.5% in air, and its vapor density is 1.1. Methyl alcohol has a specific gravity of 0.792 and is completely soluable, and nonreactive, in water. This stable compound boils at 148.1° F and freezes at -144° F. It will react with strong oxidizers, chloroform, and strong corrosives such as sulfuric acid, sodium hydroxide (caustic soda), and potassium hydroxide (caustic potash).
Methyl alcohol has a molecular weight of 32. Its chemical formula is CH3OH.
Because methyl alcohol is flammable, firefighters usually approach it with the confidence with which they approach any flammable liquid. But firefighters must remain cautious. Liquids don’t burn, but some, including methyl alcohol, produce vapors that burn. If, as is often the case, there is a time lapse between the spill and the introduction of an ignition source, the liquid has the opportunity to evaporate (especially at temperatures above its 54° F flash point). This allows the vapors to accumulate, and they’ll flow along the ground until they’re able to find an ignition source. The result will be an explosion followed by fire. Firefighters are often prepared for the fire, but not the explosion.
Deadly to drink
Then there’s the matter of toxicity. Of the four major methods of entry into the body (ingestion, inhalation, absorption through the skin, and entry through an opening in the skin), the most common method through which victims encounter methanol poisoning is ingestion. Because methyl alcohol is similar in taste to ethyl alcohol, and because of the fact that it’s called “alcohol,” many alcoholic derelicts will drink hair tonic, gasoline additives, or antifreeze containing this poison in the form of denatured alcohol, which is ethyl alcohol with enough methyl alcohol added to make it toxic.
Methyl alcohol also has distinct narcotic properties.
Ingestion is not the only danger. Inhalation of high vapor concentrations can produce drunkenness, drowsiness, light-headedness, blurred vision, blindness, unconsciousness, and death. In some cases, the effects may be delayed 24 hours or longer.
Furthermore, absorption of the material through the skin will cause similar symptoms. Contact of the liquid with the skin and eyes should be avoided. Repeated contact with the liquid will cause defatting of the skin and irritation of the skin and eyes.
The short-term exposure limit (STEL) of methyl alcohol for skin exposure is 250 parts per million, and the threshold-limit value/timeweighted average (TLV/TWA) is 200 ppm. The level that’s considered immediately dangerous to life and health (known as the IDLH) is 25,000 ppm, and the level at which methyl alcohol’s odor can be detected is 100 ppm.
In any situation where methyl alcohol is spilled, leaked, or otherwise released from its container, all the rules of preventing a fire from occurring must be followed. Always approach from upwind, and eliminate all ignition sources. Evacuation must always be considered, especially downwind. With a vapor density of 1.1, the vapors will slowly sink to the ground, flow along low spots, and accumulate in any enclosed area.
Synonyms
Carbinol
Colonial spirit
Colombian spirits
Methanol
Methyl alcohol
Methyl hydroxide
Methylol
Monohydroxymethane
Pyroxylic spirit
Resource Conservation and Recovery Act Waste Number U154
Wood alcohol
Wood naphtha
Wood spirit
Identification Numbers and Ratings
UN/NA
(United Nations/North America)
1230
National Fire Protection Association 704 rating
1-3-0
CAS
(Chemical Abstract Service)
67-56-1
RTECS
(Registry of Toxic Effects of Chemical Substances) National Institute for Occupational Safety and Health
PC1400000
STCC
(Standard Transportation Commodity Code)
Association of American Railroads, Bureau of Explosives
4909230
CHRIS
(Chemical Hazard Response Information System)
U.S. Coast Guard MAL
IMO
(International Maritime Organization)
Flammable liquid, 3.2
Spilled methyl alcohol must be prevented from entering sewers and waterways. If it does enter a sewer, warnings must be given all along the route the sewer travels, so all ignition sources can be eliminated and areas where the chances of injury from explosion or fire might exist can be evacuated. If the material enters a waterway, all downstream users of the water must be alerted immediately. This is because water taken into an industrial or commercial process will contain the dissolved flammable liquid and could cause a fire or explosion inside the building.
It’s important to keep any spilled methyl alcohol as cool as possible. The colder the environment, the slower the release of hazardous vapors. Obviously, if the ambient temperature of the environment and the liquid are both below the flash point of 54° F, the danger of fire and explosion are significantly reduced. On an extremely cold day, the danger of fire may be totally eliminated if due care is exercised.
If the temperature of the liquid (at least at the surface) is 54° F or higher, vapors sufficient to form an ignitable mixture will be present. A fine water spray or fog deployed just downwind of the spill will effectively dissolve the alcohol vapors from the air. Care must be taken if the volume of the spill is increased by the spray or fog to a size large enough to overflow its confinement area.
Alcohol-type foam applied to the surface will also slow the generation of vapors. Again, care must be taken to keep spilled material from overflowing the confinement area, since the foam is water-based.
Methyl alcohol contains only one carbon atom. So when it does burn, it burns very “cleanly,” meaning that there may be no smoke visible so long as it’s only methyl alcohol that’s burning. In bright sunlight, the pale blue flame may be almost invisible, an obvious danger. In addition, it’s a relatively “cool”-burning liquid, with a heat of combustion of only 8,419 Btu/lb., compared with gasoline’s 18,720 Btu/lb.
Carbon dioxide and dry-chemical extinguishers will be effective on small quantities of burning methyl alcohol, while alcohol-type foam will be effective on larger spills. Water spray may or may not extinguish the fire immediately; if it does, reignition is possible. However, water spray will cool the fire and eventually extinguish it.
Another method of extinguishing a methyl alcohol fire is the addition of water directly to the chemical. This dilutes the chemical, spreading its molecules so far apart that the resulting evaporation produces alcohol-air mixtures of less than 6%. That percentage is too lean to burn.
Containers and containment
Methyl alcohol containers— which can be anything from small glass bottles and cans to drums, tank trucks, and railroad tank cars—present the danger of catastrophic failure if heated by radiant heat or impinging flame. This could mean the release of flammable liquid and vapors, probably explosively. Whenever possible, a container stressed by heat should be cooled by as much water as can be safely delivered to the container, preferably by unmanned monitors.
Standard confinement practices work well for methyl alcohol. Containment ponds may be created by diking around the spill with soil, clay, sand, or any other sorbent material that’s available. A shallow trench may be dug to lead the liquid away from an unwanted or dangerous location to an area where a collection pond can be easily and quickly created.
A deep pit may also be dug to contain the liquid, and this may be more desirable. That’s because a pit’s smaller surface area means that less evaporation will take place, thereby releasing a smaller amount of toxic and flammable vapors into the air. A tarp or plastic cover may be used to cover the surface of the pit to further contain the vapors.
Liquid that accumulates in the containment pond or pit should be salvaged as soon as possible. When you’re pumping the material into a secure container, you must use explosion-proof pumps to prevent ignition from occurring.
If the material is leaking from a container and can be caught in a portable container, it can then be pumped into another secure container or back into the leaking container. In the latter case, even though the leak may continue, most of the material can be recirculated. This solves the containment problem and reduces the amount of vapors produced. Once again, if any pumping is done, the equipment must be explosion-proof.
Smaller amounts of methyl alcohol may be absorbed by clay, soil, sand, and other sorbent materials. Once absorbed, the sorbent will have the same hazards as the liquid, so disposal must be done carefully and in accordance with federal, state, and local regulations. In addition, any soil with which the methyl alcohol has come into contact will be contaminated as the liquid percolates into the ground. This soil may have to be removed.
Where methyl alcohol has entered a waterway and downstream users have been notified, the chemical can be removed from the water if the water can be contained. Aeration of the water by spraying it into the air or sparging (bubbling air through the water) will effectively remove the dissolved alcohol, usually slowly enough that dangerous accumulations of vapor won’t occur.
Glossary
Btu—British thermal unit; the amount of heat energy required to raise the temperature of one pound of water one degree Fahrenheit.
Defatting—Dissolution of the fat from human skin by a solvent.
Flash point—The minimum temperature at which a specific liquid gives off vapors sufficient to form an ignitable mixture near the surface of the liquid.
Heat of combustion—The amount of heat energy released during the total combustion of a material.
Ignitable mixture—A mixture of fuel and air within the flammable range.
Protecting and restoring health
It’s most important to guard the skin and eyes from methyl alcohol. Splash-proof goggles and face shields should be used to protect the eyes, and clothing impervious to methyl alcohol must be used to protect the skin. Manufacturers claim that Butyl rubber, chlorinated polyethylene, natural rubber, neoprene, nitrile rubber, nitrile butadiene rubber, polyethylene, polyurethane, and Viton will protect against methyl alcohol.
Positive-pressure self-contained breathing apparatus will provide respiratory protection. Do not use an organic cannister mask.
If a victim has ingested methyl alcohol and is conscious, administer a concentrated solution of salt water. Induce vomiting only if medical attention isn’t immediately available. If the victim is unconscious, keep the person warm. Medical attention must be sought immediately.
If enough methyl alcohol vapors have been inhaled to produce symptoms of intoxication, headache, drowsiness, or weakness, remove the person to fresh air immediately and keep the person calm and warm. Artificial respiration must be administered if breathing has become difficult or stopped. High concentrations (50,000 ppm) will cause optic nerve damage, central nervous system depression, or death, which may occur after exposure that lasts for an hour or longer.
If skin contact has occurred, remove contaminated clothing and wash affected areas of the body with large amounts of water. If eye contact has occurred, eyes should be flushed with water for at least 15 minutes, lifting the lids occasionally. Medical attention must be secured if eye contact has occurred. ■
