SECTION V: SAFE WORK PRACTICES

(Understand the Hazards of Your Work Environment)

Information presented is not intended to be comprehensive or all inclusive; contact your supervisor, safety officer, or the Environmental Health and Safety Office, 475-7041, for assistance or further information on any given topic.

FIRE SAFETY

Some Fire Safety Facts (and the truth about some popular misconceptions):

1. Fire will not light an exit route for you; in fact, conditions in a serious fire can very quickly make the area pitch black (e.g., from smoke, soot, etc.) and render building occupants essentially “blind.”

2. You generally have a very small time in which to exit a burning facility: a fire can be out of control in only 30 seconds from time of initiation; flashover can cause an entire room to explode into flames in only two minutes from initiation of the fire; an entire building can be in flames within only five minutes.

3. The bigger the fire, the faster it spreads. (Think “exponential”!)

4. Heat from a fire can be more threatening than the flames; temperatures can reach 600 degrees F at eye level and 1,000-1,500 degrees F around the ceiling: Keep low to the ground!

5. Lethal gases produced in a fire are more dangerous than the flames; people pass out or die from breathing smoke and toxic gases long before they are touched by the flames.

6. Take responsibility for your own rescue; don’t wait for a firefighter or someone else to do so—it may be too late!

Major causes of fire have been identified as:

· smoking materials; matches

· appliances (e.g., heating and cooking)

· misuse of electricity (e.g., overloading of circuits; faulty wiring or outlets, etc.)

· defects in heating systems

· spontaneous ignition

· failure to remove rubbish

To circumvent these possibilities, we need to:

1. Handle smoking materials and accessories properly.

2. Use electricity correctly (e.g., avoid using defective outlets; report frayed cords; check out any “burning” odor; don’t use too light a cord for a heavy horsepower machine, etc.).

3. Monitor electrical appliances closely. Keep combustible materials at least 18 inches away from appliances.

4. Keep your work area neat and clean; prevent the accumulation of rubbish and other combustible materials.

5. Prevent spontaneous ignition by proper waste disposal habits (e.g., have a metal, fire-rated container for oily rags; keep boxes, rubbish or other dangerous materials away from light panels, bulbs, boilers or other heating units, etc.).

6. See that obstructions are kept out of all passageways leading to exits, fire exit doors, and fire fighting equipment, and check to see that doors and fire exit doors in your area are easily operable.

7. Practice proper use and storage of flammable materials (e.g., keep supplies to a minimum and store in closed metal containers, labeled “flammable;” don’t use flammable liquids, gases or dusts in the proximity of open flames, sparks, incandescent surfaces or other sources of ignition).

8. Report any fire hazards you observe.

9. Know the location of:

· the nearest fire extinguisher and how to use it

· the nearest exits from your facility and the location of building fire alarms

10. Report any fire exits which have been blocked.

To start and maintain a fire, three conditions (referred to as the “fire triangle”) must be present:

1. any material that will burn (the fuel)

2. heat (flame or sparks)

3. oxygen (the normal air we breathe)

Whenever a flammable substance, heat and air come together in proper amounts, a fire can start. Remove any of the three, and you put out the fire or prevent it from starting.

A fire can be prevented or put out by:

1. removal of the fuel (e.g., to a place where there is no flame); best accomplished as a preventative measure; once a fire has begun, attempting to remove the fuel can be extremely dangerous

2. removal of the heat: (e.g., by cooling, through the application of something which absorbs heat, such as water)

3. removal of oxygen (e.g., exclusion of air by covering the fire with a wet blanket, throwing dirt on it or covering it with chemical or mechanical foam)

FIRE EXTINGUISHERS

To understand the rating on fire extinguishers, you first need a basic understanding of the three classifications of fires:

1. Class A: ordinary combustibles, such as wood, cloth, and paper.

2. Class B: flammable liquids such as gasoline, oil and oil-based paint.

3. Class C: energized electrical equipment including wiring, fuse boxes, circuit breakers and appliances.

Thus, when you see the rating (A, B, and/or C) on a fire extinguisher, you know on exactly what type of fire it is intended to be used. For example, a fire extinguisher rated as ABC can be used on all three fire classifications: ordinary combustibles, flammable liquids and electrical equipment. If the extinguisher is rated as AB, it ‘s intended use is for ordinary combustibles and flammable liquids, but not for electrical equipment. (Note: some of the newer extinguishers contain pictographs which symbolize the type of fire on which they may be used.)

Fire extinguishers are considered a first line of defense, for the purpose of putting out a small fire or containing it until the fire department arrives. Fire extinguishers have definite limitations, and are not intended to fight large or spreading fires. They have a limited range and a limited discharge time.

A fire extinguisher should be used only under these conditions:

· the operator knows how to use the fire extinguisher

· the operator is strong enough to lift and operate the extinguisher

· the extinguisher is rated for the type of fire which has occurred

· the extinguisher has the capacity to put out the fire

· everyone has left or is leaving the building

· the fire department has been called

· the fire is confined to a small area and is not spreading

· the operator’s back is to an unobstructed exit through which he/she can easily escape

· there is no (or very little) smoke in the room

If all of the above conditions are not present, evacuate the facility and do not attempt to use a fire extinguisher.

Fire Extinguisher Operation: (P A S S)

P: Pull. Pull the pin (some units require the releasing of a lock latch, pressing a puncture level, inversion or other motion)

A: Aim low. Aim the extinguisher nozzle (horn or hose) at the base of the fire.

S: Squeeze. Squeeze or press the lever (or button) above the handle.

S: Sweep. Sweep from side to side at the base of the fire until the flames appear to be out.

Watch for reflash. When it appears safe to do so, move in close; cautiously pull apart the burned area to get at hot spots. Discharge the contents of the extinguisher. Afterward, have the fire department inspect the fire scene.

FLAMMABLE AND COMBUSTIBLE LIQUIDS

All flammable and combustible liquids can be fire hazards because they are always covered with a layer of vapors, which can ignite easily. When mixed with air and contacted by an ignition source, it is the vapor, not the liquid which burns. The fuel vapor and oxygen provide two sides of the fire triangle. Flammables are considered potentially dangerous because:

· they are volatile, evaporate rapidly and continuously give off vapors

· these invisible vapors are combustible and when mixed with air in certain proportions and when confined, become explosive

· flammable vapors are heavier than air and settle to the lowest possible level, often far removed (and invisible) from the point of use; e.g., down elevator shafts, air ducts, stairwells to lower floors, etc.

· the rate of evaporation increases in a warm atmosphere or whenever the flammable liquid is close to a heat source

Not all flammable liquids present the same degree of fire and explosion hazard. The degree of flammability is determined by these measurements:

· flash point: lowest temperature at which a liquid gives off enough vapors to form a flammable mixture with air (an ignitable mixture) and produce a flame when a source of ignition is present.

· flammable or explosive range: a mixture is within its flammable or explosive range whenever the air-to-vapor proportion is sufficient to propagate a flame upon contact with an ignition source. It includes all the concentration of a vapor in air between the lower flammable limit (LFL) and the upper flammable limit (UFL). The range is usually expressed in percentages. For example, carbon disulfide has an explosive range of 1 per cent to 50 per cent. If air contains more than one or less than 50 parts of carbon disulfide vapor, the mixture can explode or burn.

Flammable liquid: A liquid having a flash point below 100 degrees F (37.8 degrees C) and having a vapor pressure not exceeding 40 lb. per square inch (absolute) at 100 deg. F (referred to as a Class I liquid). According to their flash points and boiling points, Class I liquids are further subdivided as IA, IB, and IC.

Combustible liquid: A liquid having a flash point at or above 100 degrees F (37.8 degrees C). According to their flash points, combustible liquids are further subdivided as Class II, Class IIIA, and Class IIIB.

Common sources of ignition for flammable vapors include:

· open flames

· hot surfaces

· sparks (e.g., resulting from friction, operation of electrical equipment or static electricity)

· auto-ignition

The danger of fire and explosion presented by flammable liquids can generally be eliminated or minimized by observance of safe storage, dispensing and handling procedures. Regardless of the quantities involved, each flammable liquid used should be identified by name(s) and composition to determine the extent of its flammable and health hazards. Once established, appropriate control measures should be taken. Characteristics to be considered include:

· nature of the specific liquid (including flash point and flammable/explosive range)

· toxicity

· amounts of vapor released

· ignition sources

· kinds of operations

· temperature at which the substance is stored and used

· ventilation rates

· storage location, type of building construction, etc.

Safe practices for handling flammable substances include:

1. Use only proper containers in good condition. Keep them closed when not in use.

2. Never use a container for any liquid other than that for which it is intended and marked.

3. Keep only the amount of liquid needed during the work shift (or class) on site. At the end of the shift (or class) return any unused liquid to the designated storage area (e.g., flammable storage cabinet).

4. Clean up spills of liquids immediately, disposing of cleanup rags into approved containers. Use only proper absorbents (never sawdust) to absorb a spill.

5. Never smoke, use open flames, or strike sparks where there is a possibility of igniting a flammable or combustible liquid. Post “No Smoking” signs conspicuously in buildings and areas where such smoking should be prohibited due to the presence of flammable liquids.

6. Periodically check bonding and grounding connections for electrical continuity.

Portable Containers for Flammable Liquids:

Only FM- or UL-recognized safety containers should be used for handling flammable liquids and they should be approved or listed specifically for the purpose, whether storing, carrying, dispensing, or end-use. These containers should be painted red (with a yellow band) and should include clearly legible labels that identify the contents and indicate the hazards. While not mandatory, it is recommended that all flammable liquids be transferred to “recognized” safety containers as soon as sealed shipping containers (those which are small and light-weight, with screw caps) have been opened. According to NFPA30 “Flammable & Combustible Liquids Code” (1987), a safety can is defined as “An approved container, of not more than five gallons (18.9 liters) capacity, having a spring-closing lid and spout cover and so designed that it will safely relieve internal pressure when subjected to fire exposure.” The safety can is not designed or intended for use in areas where the periodic release of flammable vapors may create a hazardous condition (such as in the trunk of an automobile). The main purpose of the safety can is preventing explosion of the overheated container while still providing the utility of a closed container. This is accomplished by providing a spring-operated cap on the pouring spout.

Bonding and Grounding to Prevent Ignition of Flammable Vapors

To prevent ignition of flammable vapors, dispensing and receiving containers should be bonded together before pouring. To be effective, all bonding connections must be metal to metal; dirt, paint, rust or corrosion should be removed from points of contact before making the connections. Bonding methods include:

1. Placing the nozzle of the dispensing container in contact with the opening of the receiving container (satisfactory if a good electrical contact is established and maintained during the entire dispensing operation).

2. Attachment of a drip-return pan to the dispensing pump (effective when the receiving container is placed on it before and during the transfer).

3. A recognized dispensing hose having a metal connector and nozzle joined by a sealed-in conductor can establish a continuous bond if the nozzle is kept in contact with exposed metal of the receiving container during the entire transfer.

Safe Storage of Flammables in Drums:

1. Each drum should be checked initially for proper labeling of contents and again periodically to assure that the label remains legible.

2. To be safe for storage or dispensing, a drum must be protected against exposure to fire and explosion hazards.

3. A pressure and vacuum relief vent (in place of the bung) should be installed on a drum as soon as it has been opened (or installed in a sealed drum containing a flammable liquid if there is a chance that it will be exposed to the direct rays of the sun or in any other way subjected to considerable variations in temperature).

4. Outside storage is preferred to inside, but if used, drums must be protected from the direct rays of the sun and other sources of heat.

5. When inside storage is used, rooms in which drums containing flammable liquids are stored or dispensed should be considered hazardous areas; however, these hazards can be eliminated or controlled through application of basic fire and accident prevention rules (e.g., adequate fire extinguishing system, strategic placement of fire extinguishers, proper ventilation and floor drainage, etc.).

Drums (or other large containers) should be connected to an adequate electrical ground when used as dispensing or receiving vessels.