Safety and emergency equipment is intended to protect you from injury if a serious incident occurs. Properly used, safety and emergency equipment can reduce the exposure to injury caused by chemicals, broken glass, burning materials, fires, and other causes.

Signs posted in sections of the labs will help you to quickly find the locations of safety showers, eyewash stations, exits, and fire extinguishers.

NOTE

For your safety, know the locations of, and how to use safety and emergency equipment. Become familiar with emergency procedures!

4.1. Fire Extinguishers
Fire extinguishers are required by National Fire Protection Association (NFPA) and OSHA regulations. In general, the regulations state that:

• Each laboratory must have a fire extinguisher of adequate size
• All fire extinguishers must be fully charged
• All fire extinguishers must be certified by an authorized service technician.

After reviewing this section, if you have any further questions regarding fire extinguishers for your lab, contact EH&S at 823-5323.

4.1.1. Types of fires and fire extinguishers

The type of extinguisher that needs to be available is based upon two factors:

• The class of fire
• The fire-fighting material.

• Class A -- paper, cloth, trash, or wood
• Class B -- oil, grease, flammable liquids
• Class C -- electrical
• Class D -- burning metal.

• Water (Class A)
• Carbon dioxide (Classes B and C)
• Dry chemical powder (Classes A, B, and C)
• Halons (Classes B and C)
• Sand or sodium chloride (Class D).

4.1.1.1. Water extinguishers

Water is effective against burning paper, cotton and wood fibers, and paper trash.

WARNING

Never use water on Class C electrical fires. You are at risk of electric shock if you use water on live electrical equipment.

Water's ability to extinguish Class A fires rests on its ability to cool the fuel and exclude oxygen. That is to say, water can remove two elements from the fire triangle discussed in section 2.6. More specifically, water excludes, or dilutes, oxygen by the formation of steam. Its high heat capacity accounts for its cooling ability.

Advantages. Water has two advantages as a Class A extinguisher:

• It is cheap and easily available
• It can be sprayed a relatively long distance.

Water worsens Class B fires because most fuels have a density less than that of water

The fuel will float on top of the water and spread as the water flows to the lower levels

While floating on the water's surface, the fuel's oxygen supply is not disturbed nor is the fuel cooled

Water cannot be used on Class D fires because of the chemical reactions -- specifically oxidations -- which can occur between water and the metal.

4.1.1.2. Carbon dioxide extinguishers

Carbon dioxide is suggested for fires involving delicate instruments and optical systems.

WARNING

Never use carbon dioxide extinguishers against fires caused by lithium aluminum hydride or potassium.

Carbon dioxide extinguishes Class B and C fires by depleting oxygen and cooling the fuel.

Advantages. Carbon dioxide has several advantages:

• It is cheap and readily available
• It leaves no residue
• It requires no propellant since it is delivered as a gas
• It is effective in smothering and cooling burning liquids such as hydrocarbons
• It is nonconductive and therefore safe to use on electrical fires.

• It has a low efficiency in extinguishing fires
• It has a short target range
• It is an asphyxiant (that is, causes suffocation)
• It is delivered at an extremely low temperature and can cause thermal shock and create hairline cracks in circuit boards
• It can cause frostbite on contact with the skin.

Dry chemical monoammonium phosphate (MAP) extinguishers can be used for Class A, B, and C fires.

The dry chemical monoammonium phosphate (MAP) extinguisher, also called the ABC or all-purpose extinguisher, is a broad-ranged extinguisher. The MAP's diversity contributes to the fact it is the type most often found in homes and cars. The MAP extinguisher is suitable for Class A, B, and C fires. Do not use it on organic metal (Class D) fires.

Advantages. The MAP extinguishers have the same advantage as carbon dioxide extinguishers in that they smother the fire and choke off the oxygen supply. This advantage makes MAP extinguishers ideal for use on virtually any material except organic metals.

Disadvantages. However effective, the MAP extinguishers have some disadvantages:

• The MAP extinguishers leave a sticky residue or powder that is especially troublesome in electronic equipment
• The MAP extinguishers have no cooling effect on the fuel or other heated equipment. An additional coolant is sometimes needed to prevent flareup.

Dry chemical potassium or sodium carbonate extinguishers are effective against burning grease and oil.

WARNING

If you are using a coolant to prevent flare-ups in a fire extinguished by dry chemicals:

Turn off or disconnect all electrical equipment!

These dry chemical extinguishers are like MAP extinguishers except that they contain either potassium or sodium carbonate as the extinguishing agent. They can be used on Class B and C fires, but not Class A nor Class D fires.

Advantages. Potassium or sodium bicarbonate extinguishers smother burning grease much faster and more certainly than the MAP extinguisher can. The potassium or sodium bicarbonate interferes with the clumping of fats and oils.

Disadvantages. One chief disadvantage is the sticky residue, which, like the MAP extinguisher, presents the same problems when used on electrical equipment. Also, potassium or sodium bicarbonate extinguishers can have the same problems as the MAP extinguisher in requiring an additional coolant.

4.1.1.5. Halon-gas extinguishers

Halon-gas (halon) extinguishers are effective against electrical fires without causing low-temperature stress effects to electronic equipment.

Halon can be used for Class B and C fires. It is somewhat less effective with Class A fires (see Disadvantages below). Do not use halon on a Class D fire.

Halon-gas (halon) extinguishers put out fires by choking off oxygen. The halon gas is a non-reactive chlorofluorocarbon.

• It leaves no messy residue
• It is not a coolant, and thus causes no temperature stress to sensitive electronic equipment
• It is nonconductive and therefore safe to use on live electronic equipment.

• Halon can produce toxic gases depending on the model used (Halon CF4 does not produce toxins)
• Halon can damage the earth's ozone layer. Recent studies have shown that halon is especially destructive to ozone. Because of this damage, an alternative to halon is being investigated.

4.1.1.6. Extinguishers for Class D fires

Extinguishers for Class D fires are specially-formulated to treat organic and alkali metals that cannot be safely extinguished by other fire extinguisher agents.

WARNING

Never use a Class D-rated extinguisher for Class A, B, or C fires. See the guidelines below.

Class D fires are caused by ignition of organic metals such as lithium (an alkali metal), aluminum, or sodium. Class D fires are particularly troublesome to extinguish because of the intensity with which they burn and their ability to react chemically with normal extinguishing agents. As an example, carbon dioxide will not react with cold sodium but accelerates the burning rate of ignited sodium. Two agents that are used to extinguish Class D fires are sand and sodium chloride.

Guidelines. To extinguish Class D fires:

• Use water, foam, carbon dioxide, or halons on fires involving alkali metals
• Use graphite, soda ash, or powdered sodium chloride on fires involving alkali metals. Be very sure that the extinguishing agent is dry or the moisture can react with the metal.

4.4.1. Eye protection

WARNING

Do not wear contact lenses in the laboratory if there is a risk of the lenses:

Reacting with lab chemicals

Being damaged by lab chemicals.

Specific goggles for protection against laser hazards, ultraviolet, or other intense light sources must be worn without exception.

Eye protection must be worn at all times in all laboratories when working with chemicals, conducting an experiment, or using special machinery. Eye protection is not required when conducting an instrumental study.

Prescription glasses will not always provide adequate protection from injury to the eyes. The minimum acceptable protection is hardened glass or plastic safety glasses.

NO YES

Use safety goggles or face shields of hardened plastic or safety glass. They acceptable eye protection for preventing splashing chemicals, flying particles, or other products of violent chemical reactions from getting into your eyes.

4.4.2. Gloves

Gloves made for skin protection must be worn when working with toxic/corrosive materials or with materials of unknown toxicity. Gloves should be selected on the basis of material being handled and their suitability for the particular laboratory operation. See your Lab Manager or EH&S for chemical compatibility and protection information.

4.4.3. Footwear

Footwear must be worn at all times in the laboratory. Solid-toes shoes are the only type of footwear accepted in the labs. Open-toed shoes are prohibited. They do not protect against glass or spilled chemicals.

4.4.4. Unacceptable clothing

Do not wear loose, skimpy, or torn clothing, dangling neckties, over-large or ragged laboratory coats, shorts or halter tops. Laboratory clothing should protect yourself. If there is a possibility of contamination, cover personal clothing that will be worn home with protective apparel.
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