meyer, chemistry of hazardous materials, fifth ed. © 2010 by pearson education, inc., upper saddle...

Meyer, Chemistry of Hazardous Materials, Fifth Ed.© 2010 by Pearson Education, Inc., Upper Saddle River, NJ

Chemistry of Hazardous MaterialsFifth Edition • Eugene Meyer

Chapter 3

Flammable Gases and Flammable Liquids


Liquid Flammability

• Lower explosive limit– Minimum vapor concentration

• Upper explosive limit– Maximum vapor concentration

• Flammable range– Numerical difference between upper, lower

limits


Liquid Flammability (cont’d)

• Combustible gas monitor– Determines concentration of substance in

air


Temperature and Flammable Liquids

• Flashpoint– Minimum temp at which there is sufficient

vapor to form ignitable mixture


Temperature and Flammable Liquids (cont’d)

• Fire point– Temp at which self-sustained combustion

occurs• Auto ignition point

– Temp at which self-sustained combustion occurs without ignition source


OSHA/NFPA Definitions

• Flammable liquid (Class I liquid)– Flashpoint < 100° F

• Combustible liquid (Class II liquid)– Flashpoint > 100° F


“Emptied” Tanks

• When liquid is removed, some vapor always remains within container or storage tank– Precautions always

should be exercised

Courtesy of GfG Instrumentation, Inc., Ann Arbor, Michigan.


Accelerants

• Flammable or combustible solids, liquids, gases

• Used to initiate, promote fire spread• Confirmation by lab analysis


Resource Conservation and Recovery Act

• Wastes classified by ignitability characteristics

• Subject to EPA regulations as it pertains to treatment, storage, disposal


RCRA Characteristic of Ignitability

• Waste exhibits ignitability if it is– flammable gas, as defined in DOT

regulations – liquid with flashpoint equal to or less than

140º F (60º C)– material other than liquid capable “of

causing fire by friction, absorption of moisture, or spontaneous chemical”


RCRA Characteristic of Ignitability (cont’d)

• Waste exhibits ignitability if it is– flammable solid, as defined in DOT

regulations – oxidizer, as defined in DOT regulations


Storing and Transporting Compressed Gases

• Compressed gas– Gas confined under

pressure• Liquefied

compressed gas– Under moderate

pressure, gas liquefies


Compressed Gas Storage

• Avoid damaging cylinder• Secure in upright position• Protect valve using protective cap• When moving cylinders, they should be

secured to appropriate cart


Compressed Gas Transport

• DOT approves containers for use only upon heating (70° F to 130° F) and where pressure does not exceed five-fourths of container’s service pressure

• Cylinders must be secured for transport


Compressed Gas Transport


General Hazards ofCompressed Gases

• Cylinders that rupture due to rapid increase in pressure may behave as airborne missiles

• Flammable gases can mix with air, ignite


Transport Vessels

• Compressed gases, liquefied compressed gases routinely transported within cargo tanks, railroad tank cars

• Special concern given to situations where containers are engulfed in fire


Transport Vessels


Incidents Involving Release of Compressed Gases

• Vessels exposed to intense heat are likely to rupture

• Contact CHEMTREC• Determine degree of hazard• Use water to cool exposed containers• With small leaks, use water fog to

disperse gas or vapor


Incidents Involving Release of Compressed Gases (cont’d)

• Don’t try to move cylinder if concentration of escaping gas or vapor is in flammable range

• Use total encapsulating suit, self-contained breathing apparatus when moving slowly leaking cylinder

• Position cylinder so point of leakage becomes uppermost part of cylinder



• Emergency responders should never approach head or end of tank or cylinder

• Grounding required to transfer substances between vessels

• Firefighters in area of leaking gas should wear total encapsulating suits– Use self-contained breathing apparatus



• Combating major fire involving flammable compressed gas should not be undertaken unless escape of flammable gas from cylinder or tank can be stopped


Evacuation

• With cylinders containing flammable or nonflammable gas, personnel should be evacuated to at least 1000 ft in all directions (2000 ft for public)

• Tanks require 2500 ft for firefighters (5000 ft for public)

• Use unmanned monitor to cool tank


Storing Flammable Liquids

• When not in use, containers and tanks should be sealed to prevent spills or vapor leakage

• Class I flammable liquids should be dispensed only from containers or tanks that have been electrically grounded

• OSHA regulates storage of flammable liquids in workplace


Storing Flammable Liquids (cont’d)

• Allowable maximum volume varies with – Flashpoint of liquid– Manner by which it is stored– Whether storage is indoors or outdoors

Courtesy of Justrite Manufacturing Company, Des Plaines, Illinois.


Storing Flammable Liquids (cont’d)

Courtesy of A & A Sheet Metal Products, Inc., SE-Cur-All® Products, LaPorte, Indiana


Portable Tanks

• Closed container not intended for fixed installation possesses liquid capacity of 60 gallons

• Portable tanks require one or more devices for emergency venting under fire conditions


Storage Within Stationary Tanks

• Types– Atmospheric tank– Low-pressure tank– Pressure vessel

• Tank farm: collection of tanks– Containment is

provided


Transporting Flammable Liquids

• DOT authorizes bulk shipments when shipper, carrier have loaded them into transport vessels constructed according to specified requirements that comply with – Certain allowable maximum filling limits– Testing– Maintenance– Marking, placarding– Other requirements


Transport by Motor Carrier

• Types– Cargo vans

• Liquids contained in steel drums– Cargo tank/semi-trailer combination


Transport by Railroad Tank Car

• Types– Nonpressure tanks

• Outlets, external heater lines located on bottom• Valves, pressure-relief devices located on top

– Pressure tanks• Internal pressure tested to 100-600 psi


Thermal Protection

• Thermally “insulated” tank cars: constructed so external heat is transferred to contents very slowly under normal conditions

• Thermally “protected” tank cars: constructed so external heat cannot be transferred to contents under abnormal conditions


Responding to FlammableLiquid Incidents

• Most serious incident involves release of flammable liquid– And/or ongoing fire impinges vessel

• Boiling liquid expanding vapor explosion (BLEVE)– When external heat is applied to vessel,

contents produce more vapor, increasing internal pressure, causing vessel to rupture


Responding to FlammableLiquid Incidents


General Procedures

• Determine type, amount of flammable liquid– Chemical nature

• Identify other hazardous materials in immediate vicinity

• Contact CHEMTREC, National Response Center

• Select appropriate extinguishing agent


General Procedures (cont’d)

• Use water fog to disperse vapors for small spill or leak

• Cool nearby containers• When vapor has not yet ignited, monitor

concentration of flammable vapor in air– Use fog to disperse vapors, reduce

concentration



• Steps to stop leak should be done only when concentration of vapors is outside flammable range

• Foam may be used to confine flammable vapor

• Dikes can be used to prevent spread of liquid



• Move upright railroad cars from overturned tank cars whenever practical

• Firefighters should wear total-encapsulating suits, self-contained breathing apparatus


Evacuation

• With insufficient water– 2500 ft for firefighter– 5000 ft for public

• With sufficient water– 1000 ft for firefighters

• Use unmanned monitors to cool a tank

meyer, chemistry of hazardous materials, fifth ed. © 2010 by pearson education, inc., upper saddle...

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