melton safety presentation

8/7/2019 Melton Safety presentation

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SAFETY IN THE WORKPLACE

FIRE EXINGUISHERS


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Workplace fires and explosions kill 200 and injure morethan 5,000 workers each year. In 1995, more than 75,000workplace fires cost businesses more than $2.3 billion.

"Fires wreak havoc among workers and their familiesand destroy thousands of businesses each year, puttingpeople out of Work and severely impacting theirlivelihoods," said Secretary of Labor Robert B. Reich(1996, October 8). "The human and financial tollunderscores the serious nature of workplace fires."


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Employers should train workers about fire hazardsin the workplace and about what to do in a fire emergency.If you want your workers to evacuate, you should train them

on how to escape. If you expect your workers to use firefightingequipment, you should give them appropriate equipment andtrain them to use equipment safely. (See Title 29 of the Codeof Federal Regulations Part 1910 Subparts E and L; and Part1926 Subparts C and F.)


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Class A fires are ordinary materials like

burning paper, lumber, cardboard,plastics etc.


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oClass B fires involveflammable or combustibleo liquids such as gasoline,kerosene, and commonoorganic solvents used inthe laboratory.


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Class C fires involve energized electrical equipment, such asappliances, switches, panel boxes, power tools, hot plates and

stirrers. Water is usually a dangerous extinguishing medium forclass C fires because of the risk of electrical shock unless aspecialized water mist extinguisher is used.


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Class D fires involve combustiblemetals, such as magnesium, titanium,

potassium and sodium as well aspyrophoric organometallic reagentssuch as alkyllithiums, Grignards anddiethyl zinc. These materials burn athigh temperatures and will reactviolently with water, air, and/or other

chemicals. Handle with care!!


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Class K fires are kitchen fires. This class was added to the NFPAportable extinguishers Standard 10 in 1998. Kitchen extinguishersinstalled before June 30, 1998 are "grandfathered" into the standard.


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Here are some typical extinguishers and their uses:


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Water extinguishers are suitable for class A (paper, wood etc.)fires, but not for class B, C and D fires such as burning liquids,electrical fires or reactive metal fires. In these cases, the flames

will be spread or the hazard made greater!


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Dry chemical extinguishers are useful for class ABC fires and are

your best all around choice. They have an advantage overCO2 extinguishersin that they leave a blanket of non-flammable material on the extinguishedmaterial which reduces the likelihood of reigniting. They also make aterrible mess but if the choice is a fire or a mess, take the mess!

Note that there are two kinds of dry chemical extinguishers!


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Type BC fire extinguishers contain sodium or potassium bicarbonate.


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Type ABC fire extinguishers contain ammonium phosphate.


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CO2 (carbon dioxide) extinguishers are for class B and C fires.They don't work very well on class A fires because the material usually

reignites. CO2 extinguishers have an advantage over dry chemical in that theyleave behind no harmful residue. That makes carbon dioxidea good choice for an electrical fire involving a computer or other delicate

instrument. Note that CO2 is a bad choice for a flammable metal firessuch as Grignard reagents, alkyllithiums and sodium metal because CO2

reacts with these materials. CO2 extinguishers are not approved for class D fires!


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Metal/Sand Extinguishers are for flammable metals (class D fires)

and work by simply smothering the fire withpowdered copper metal or sodium chloride (NaCl).You should have an approved class D unit if you

are working with flammable metals.


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The copper extinguishing agent is preferred for fires involving lithiumand lithium alloys. It is the only known lithium fire fighting agent whichwill cling to a vertical surface thus making it the preferred agent on three

dimensional and flowing fires.


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Sodium chloride works well for metal fires involving magnesium, sodium(spills and in depth), potassium, sodium potassium alloys, uraniumand powdered aluminum. Heat from the fire causes the agent to cake

and form a crust that excludes air and dissipates heat.


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Use a mental checklist to make a

Fight-or-Flight Decision.Attempt to use an extinguisher only

ifALL of the following apply:


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The building is being evacuated (fire alarm is pulled)

The fire department is being called (dial 911).

The fire is small, contained and not spreading beyond its starting point

The exit is clear, there is no imminent peril and youcan fight the fire with your back to the exit.

You can stay low and avoid smoke.


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The proper extinguisher is immediately at hand

You have read the instructions and know how to use the extinguisher.


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IF ANY OF THESECONDITIONS HAVE NOT BEEN MET, DON'T FIGHTTHE FIRE YOURSELF. CALL FOR HELP, PULL THE FIRE ALARM ANDLEAVE THE AREA


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Operation of Fire

Extinguishers


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Extinguishers have a label on thefront with operating instructions. The

operating principle is the same for all

extinguishers - PASS:


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Pull the pin. Extinguishers have a safety mechanism to prevent the extinguisherfrom being accidentally discharged. Usually the safety mechanism involves a pinheld in place by a plastic tie. Since the plastic may stretch before breaking or maybe difficult to break, twisting the pin first will break the tie easily.


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Aim at the base of the fire at the fuel. Aiming at the fire does no good,since the fire is only the products of combustion coming off the fuel.


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Squeeze the two parts of the handle to

operate the valve and discharge the extinguishing agent.


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Sweep the extinguishing agent rapidly back and forth to cover all of the

fuel and separate the fuel from the fire. In the case of flammableliquid fires, technique is very important. The bigger the fire, the morechance the fire will flashback because of the heated vapors.


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Maintenance of Fire Extinguishers


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Extinguishers require routine care. Read your operator's

manual and check the condition of the extinguisher every

month. Shake your dry chemical extinguisher to get the powderevenly dispersed since the powder has a tendency to cake.

Have the extinguisher serviced once a year by a fire extinguisher

company, which you can find in the yellow pages under

"Fire Extinguishers."


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Reusable models must be recharged after every use. Sometimes thepowder will lodge in the valve assembly after one use and the pressurewill bleed off even though your pressure gauge shows pressure isremaining. A partially discharged unit might as well be empty.


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Disposable fire extinguishers can be used only once. They must bereplaced after one use. Disposable extinguishers usually do not havea pressure gauge and rely on a button to let you know if pressure isstill good. The label will tell you if the extinguisher is rechargeable.


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Each extinguisher should be installed in plain view near an escaperoute and away from potential fire hazards such as kitchen stoves,where you can reach it if there's a fire.


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Many Fire Departments offer training and practice in the use of portablefire extinguishers. Phone or email your local Fire Departmentoffice to askabout training.

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