year fire kills thousands of people and destroys billions of dollars worth of
property. These losses can be
prevented. Physical plant
workshops, art classrooms, laboratories, theater scene shops, etc.─stocked
with flammable and combustible liquids, gases, and solids─contain all the
elements of a potential fire.
a fire to start, three conditions must be met at the same time.
must be something to burn─a fuel; a source of oxygen (an oxidizer); but
most importantly, there needs to be an initiating event that imparts sufficient
energy to start a chain reaction─an ignition source. These three necessary factors are each at the corners of an
equilateral triangle, the fire triangle, whose overlap is a chain reaction that
results in the rapid oxidation of a fuel─fire.
fire will not always start when the three legs of the fire triangle meet, unless
all three elements are present in the required amounts. For instance, vapors
from a flammable liquid must be mixed with a certain amount of air in order to
ignite and propagate a flame.
vapors and gases will burn only if their concentration in air is within a
certain range (called the flammable range).
The lowest concentration at which a fuel/air mixture will burn is called
the Lower Flammable Limit (LFL); below this there is too little fuel (the
mixture is too lean). The highest
concentration at which a fuel/air mixture will burn is the Upper Flammable
Limit (UFL); above this there is not enough oxygen (the mixture is too
rich). Within this flammable range
(sometimes also called the Lower and Upper Explosive Limits─LEL and UEL),
there is enormous potential for fire or explosion.
For example, acetone will burn only when the vapor concentrations in air
are between 2 ½ percent and 13 percent.
Adjustment of work habits is necessary to keep the vapor concentration too lean to burn─that is, well below the LFL. Usually it is recommended to keep the vapor concentration below 25 percent of the LFL.
common measure of a liquid's ease of ignition is its flash point (the lowest
temperature at which sufficient vapors form above the liquid to produce an
ignitable mixture with air). Solvents
with flash points at or near room temperature are particularly hazardous because
of the ease at which they catch fire when an ignition source is present.
Substitution of high flash point solvents for more dangerous low flash
point solvents reduces the amount of flammable vapors produced and makes a fire
less likely. For example, mineral
spirits (flash point over 100°F)
is much safer than a similar naphtha product (flash point of 28°F).
transportation regulation purposes, the U.S. Department of Transportation
classifies all liquids with a flash point below 100°F
as flammable and all liquids with flash points at or above 100°F
as combustible. For storage
regulation purposes, the National Fire Protection Association (NFPA) has further
subdivided flammable liquids into Classes IA, IB, and IC, and combustible
liquids into Classes II, IIIA, and IIIB.
combustible liquids are not considered to be serious fire hazards at ambient
temperatures. However, heating a
solvent to a temperature at or near its flash point will increase its fire
hazard─causing a combustible liquid to act as if it were a flammable
liquid. This is because raising the temperature increases the amount
of flammable vapor produced, thus contributing to the fuel leg of the fire
triangle. For instance, turpentine
(whose flash point is 95°F)
must be used with extra care at high ambient temperatures or in direct sunlight.
A material's vapor pressure is a measure of its ability to evaporate. The higher the vapor pressure, the higher the evaporation rate (and the lower the flash point), which results in more vapors being produced. Consequently, liquids with high vapor pressures are greater fire hazards. Substitution of a lower vapor pressure solvent, such as ethyl alcohol for the higher vapor pressure acetone, reduces both the amount of vapors and the risk of fire.
measure of a material's ease of ignition is its auto-ignition temperature.
This is the temperature at which, in the presence of sufficient oxygen, a
material will ignite on its own and burn (spontaneous ignition).
For example, carbon disulfide (with an extremely low auto-ignition
temperature of 212°F)
must be kept away from all heat sources. Large
amounts of highly flammable materials should be stored in a laboratory safe
refrigerator (sometimes referred to as explosion-proof, although this
designation is not quite correct).
Gases and Solids
tall cylinder of acetylene welding gas that is a familiar sight in many physical
plant facilities and art studio workshops should be stored and used properly
according to the OSHA regulations.
that burn include paper, wood, and cloth. These
pose a fire hazard mostly because they are not usually treated as potential
fuels. Solid materials (like rags
or paper soaked with a flammable liquid) are quite dangerous due to the rapid
evaporation of the flammable liquid from their surfaces.
that burn (called pyrophoric) are an especially serious fire hazard, because it
is very hard to put these fires out. For
the most part these materials are not frequently encountered on campus.
it is impossible to eliminate oxygen from the fire triangle, fire prevention
depends on trying to eliminate sources of ignition and restricting the amount of
flammable and combustible liquids. Some
simple rules that should always be followed to eliminate sources of ignition
must be prohibited in all laboratory areas,
electrical equipment in ventilated hoods and spray booths must be explosion-proof
and well maintained, and
sources of light, such as projectors and lasers, should be kept away from
of the major ways to reduce fire hazards in the storage of flammable and
combustible liquids are:
the least hazardous materials possible,
the amounts stored to a minimum, and
Using safe storage procedures and containers.
storage of flammable materials requires that the materials be adequately labeled
as to their contents, fire hazards, and safe handling procedures.
Flammable liquids should carry the following label:
AWAY FROM HEAT, SPARKS & OPEN FLAMES
CLOSED WHEN NOT IN USE
pertinent to preventing and extinguishing fires is contained in Section V of the
product's Material Safety Data Sheet (MSDS).
This section contains the material's flash point and flammability range,
as well as the proper fire fighting equipment to use in the event of a fire.
This data, and the information about the product's physical properties
contained in Section IV, are valuable for proper labeling, comparing various
products flammability range, and choosing less hazardous materials.
method of labeling is the NFPA 704 System of Hazard Identification.
This is a symbol hazard system intended for use on fixed locations, such
as laboratory entrances, storage rooms, etc.
It tells a firefighter or other person of the hazards in the area.
This NFPA system uses the NFPA diamond as the symbol.
The numbers 0 through 4 are placed in the three upper quadrants of the
diamond. These represent the degree
of hazard for health hazard, flammability, and reactivity.
The number 0 indicates the least degree of hazard, and 4 the highest.
The bottom quadrant is often used for the radiation hazard symbol or
water reactivity (a letter W with a bar through it).
and state fire codes limit the amounts of flammable and combustible liquids that
can be stored in various locations. Check
with your local fire department.
best location to store large amounts of flammable and combustible liquids is in
a separate outside building. If
this is not possible, then a suitable flammable storage cabinet or inside
storage room should be built. NFPA
30 (Flammable & Combustible Liquids Code) describes the requirements for
inside storage rooms. These can
include walls, floors and ceiling with a fire resistance rating of 2 hours,
class B fire doors, automatic fire protection systems, and mechanical
ventilation─depending on the amount stored.
If flammable liquids (Class I) are stored in this room, then explosion
vents, and Class I-Division 2 electrical wiring and fixtures are required.
Only flammable and combustible liquids should be stored in these rooms.
containers of flammable and combustible liquids must be stored in accordance
with established safety procedures that isolate incompatible materials from each
other. In addition, the amounts stored should be kept to a minimum to reduce the
risk of fire. Note that in
instructional laboratories, the largest container size permitted for flammable
liquids is 1 gallon (or a 2 gallon safety can).
Quantities of flammable liquids exceeding one pint should be stored in safety cans that are approved or listed by recognized testing laboratories, e.g., Factory Mutual or Underwriters Laboratories. These have self-closing covers, flame arrestor screens, and pressure release devices. Similar containers are used for storage of waste solvents.
often come in 5 gallon and 55 gallon drums. The maximum size of drum that
should be stored is 5 gallons; 55 gallon drums should only be stored in a
separate storage area away from heat and sunlight.
the amounts of flammable and combustible liquids present are too small to
warrant a separate storage room, they should be stored in a flammable storage
cabinet that has been built to meet OSHA and NFPA standards.
Cabinets should be labeled in large letters: FLAMMABLE KEEP FIRE AWAY.
storage cabinets do not need to be vented unless required by local codes.
A maximum of 120 gallons of Class I, II and IIIA liquids may be stored in
a flammable storage cabinet; of this total, not more than 60 gallons may be of
Classes I and II. A maximum of not
more than three such cabinets may be located in a given fire area (an area of a
building separated from the rest of the building by construction having a fire
resistance rating of at least one hour).
fires are started by the improper dispensing of flammable liquids.
The pouring and mixing of flammable materials should be restricted to a
special well-ventilated area. When
dispensing from drums, use approved transfer pumps or drum faucets.
When pouring flammable liquids from a drum to a metal container (e.g., a
safety can), ground the drum and bond the metal container to the drum to prevent
the build-up of any static charge. This
bonding is done with a braided wire with large metal clips to connect the drum
and container, and a grounding line from the drum to a ground.
liquid spills can be reduced, and in some cases eliminated, by proper training
and good housekeeping techniques. Should a spill occur, it must be quickly and
safely cleaned up to prevent its flammable vapors from igniting.
A large quantity of absorbent (e.g., commercially available spill
pillows) should be kept on hand in all areas used for storage, dispensing, or
use of flammable liquids.
Once a spill has been collected onto the absorbent, it must be treated as a flammable material. A metal container should be used to contain the absorbed flammable material, and disposed of separately from the regular trash─preferably wrapped in a separate plastic bag.
spills of flammable liquids (more than a quart) are especially dangerous and
need special cleanup procedures.
If you do not succeed in preventing a fire, then you have to extinguish it. The timely use of the proper fire extinguisher will slow a fire and give professional fire fighters time to arrive. There is a wide variety of fire extinguishers─each designed to fight a particular type of fire. The use of the wrong fire extinguisher will prove ineffective on a fire, and may even spread the fire.
class of fire has special fire extinguishers that are recommended for it.
Common types include the following:
A Types: For areas containing
ordinary combustibles, a Class A fire extinguisher is needed.
Water-based Class A fire extinguishers include pressurized water,
loaded stream, anti-freeze, and aqueous film-forming foam (AFFF) types.
Inverting Class A fire extinguishers (e.g., soda acid and foam) are
obsolete and must not be used.
ABC Multipurpose Dry Chemical: Many physical plant workshops, laboratories, and art
departments contain a variety of ordinary combustibles, solvents, and
electrical equipment. The use
of a Class ABC multipurpose dry chemical fire extinguisher, which can easily
handle any of these classes of fires, is recommended.
The multipurpose fire extinguisher sprays a stream of ammonium
dihydrogen phosphate that cuts off the fire's supply of oxygen and smothers
the flame. A problem particular
to the art field is that the powder is gritty and corrosive, and can damage
some artifacts and sensitive electrical equipment.
BC Carbon Dioxide: If the workspace contains no substantial amounts of Class
A materials, then a Class BC carbon dioxide fire extinguisher will suffice.
This piece of fire fighting equipment sprays a cloud of pressurized
carbon dioxide to displace air and cut off the fire's oxygen.
Fire extinguishers are also assigned Class A and B numerical ratings
based on their relative effectiveness in extinguishing a particular type of
fire. For example, a 4A rating
can put out a bigger class A fire than can a 2A rating. The size of rating needed will depend on the relative amounts
of the flammable materials present. Where solvents are present, usually a
12BC rating is required.
Automatic sprinkler systems are commonly used in public buildings as a fire suppression method. There are several types, including water and halon. This newsletter is just going to briefly discuss these types.
system of water pipes that sprays a mist when activated by the heat of a fire is
common in older buildings. Water
sprinkler systems are, however, not common in museums and libraries for a
variety of reasons.
Halon automatic sprinkler systems spray a halogenated chemical─either Halon 1301 or 1211─onto the fire. Halons, while effective fire retardants, decompose to toxic gases (such as hydrogen fluoride and hydrogen chloride) when heated. In addition, the halons themselves can be toxic at the high concentrations encountered in total flooding systems. The use of halon deluge systems must be carefully planned, must only be used in enclosures, and never in conjunction with an automatic door closing mechanism that might trap workers or visitors. See in particular the NFPA standards on halons. Halon extinguishing systems are also quite expensive.
for Fire Fighting
has detailed regulations concerning firefighting procedures.
All employers must have a written fire prevention plan.
OSHA regulations allow for three situations:
evacuation in case of fire alarm;
Partial evacuation with some employees allowed to use fire extinguishers; and
All employees allowed to use fire extinguishers. If any employees are allowed to use fire extinguishers, then OSHA specifies training and other requirements.
you are subject to use a fire extinguisher, the first step is to ask yourself
whether or not you can effectively fight the fire at hand.
Small trash fires can be easily be put out; but when threatened with a
large and fast moving fire, sound the alarm and wait for professional fire
fighters to arrive. An easy four-step
plan will help in the event of a fire:
you think you can handle the fire, sound the fire alarm in order to set the
emergency plan in operation.
the closest fire extinguisher that conforms to the type of fire. Remember,
the wrong extinguisher will be ineffective, and can actually spread a fire.
the fire extinguisher and follow the directions for use.
(You should have had previous practice in using the fire
extinguisher.) Remember, even
when the fire appears to be extinguished, it might not be.
Many smoldering fires are still hot enough to re-ignite.
Before you leave, make sure it is completely out.
If at any time you feel overwhelmed, or the extinguisher charge runs out, leave the area and wait for the professional fire fighters to arrive. Your guidance as to what type of fire and where it started will be quite valuable to them. The actual procedures should be part of your fire prevention training, which should include actual practice in the use of fire extinguishers.
fighting equipment must be well maintained and checked periodically for pressure
and integrity─this can be inexpensively contracted out to an extinguisher
fire extinguishers must be placed prominently according to OSHA regulations (and
not used for bookends, coat racks, or door stops).
A fire extinguisher cannot help in the event of a fire if nobody can find
it or it does not work. Other types
of fire suppression equipment, such as sprinkler systems, must also meet the
appropriate OSHA standard.
Remember! Don’t cut corners when working with hazardous materials. Work safely by constantly remaining aware of the hazards of the materials you are working with. Watch those storage areas where materials can accumulate. This is one of the most common problems on our campuses throughout the state.