SOPs: Flammables, Organic Peroxides, Self-Heating, Emits Flammable Gas; Self-Reactives

Flammables (Liquids, Aerosols, Gases, Solids)

Definitions and Other Important Information
  • Flammable and combustible substances release vapors, and it is the vapors that can ignite and are therefore a common source of fire hazard.  Laboratories routinely use aerosols, gases, liquids, and solids; the gases pose special hazards since leakage or escape of the gas can produce an explosive atmosphere in the laboratory.
  • Hazard Communication Standard (29 CFR 1910.1200):
    • GHS Definitions, Signal Words, and Hazard Statements are summarized in this table for each Flammables Hazard Class (Liquids, Aerosols, Gases, Solids).
    • Detailed descriptions are found in Appendix B of 1910.1200.
  • NFPA 30 (“Flammable and Combustible Liquids Code”):
    • Flammable: Class IA ‐ Flash Point less than 73°F; Boiling Point less than 100°F
    • Flammable: Class IB ‐ Flash Point less than 73°F; Boiling Point equal to or greater than 100°F
    • Flammable: Class IC ‐ Flash Point equal to or greater than 73°F, but less than 100°F
    • Combustible: Class II ‐ Flash Point equal to or greater than 100°F, but less than 140°F
    • Combustible: Class IIIA ‐ Flash Point equal to or greater than 140°F, but less than 200°F
    • Combustible: Class IIIB – Flash Point equal to or greater than 200°F
  • NFPA 704 (“Standard System for the Identification of the Hazards of Materials for Emergency Response” or “NFPA Hazard Diamond”):
    • 0    Substance will not burn under typical fire conditions.
    • 1    Flashpoint ≥ 93.4°C
            Flashpoint ≥ 200°F  Substance requires considerable preheating, under ambient temperature conditions, before ignition and combustion can occur.
    • 2    93.4°C > Flashpoint ≥ 37.8°C
            200°F > Flashpoint ≥ 100°F  Substance must be moderately heated or exposed to relatively high ambient temperatures before ignition can occur.
    • 3    37.8°C > Flashpoint ≥ 22.8°C  or [(22.8°C > Flashpoint) and (Boiling Point ≥ 37.8°C)]       100°F > Flashpoint ≥ 73°F  or [(73°F > Flashpoint) and (Boiling Point ≥ 100°F)]  Substance can be readily ignited under almost all ambient temperature conditions.
    • 4    22.8°C > Flashpoint and 37.8°C > Boiling Point
            73°F > Flashpoint and 100°F > Boiling Point
            Substance will rapidly or completely vaporize at ambient temperature and will burn readily.


Standard Operating Procedures
  • Know the flammability properties of the chemicals being used.  Pay particular attention to substances with a GHS Hazard Category of 1 or 2, or an NFPA fire hazard rating of 3 or 4.
  • Containers must have the required identifying labels.
  • Amounts in Labs.  
    • Maximum Container Size on Benchtop/Shelves.  “Secondary” and “Immediate Use” containers with small quantities of flammables (≤ 500 ml) that have a GHS Category 2, 3, or 4 (or an NFPA 704 rating of ≤ 3) can be used/stored on the laboratory countertops & shelves, provided that they are kept in secondary containment (spill) trays.
    • When handling larger containers (> 500 ml) use a fume hood.   Store these in the flammables cabinet.
    • Total Amount on Benchtop/Shelves.  Within individual laboratories, storage of flammable liquids (including wastes) outside of approved flammable storage cabinets or safety cans (i.e., open shelves & countertops) must not exceed 10 gallons per 100 square feet of laboratory space, or 600 gallons total (NPFA 45: “Fire Protection for Laboratories Using Chemicals”).  There is no laboratory within RNS that comes close to these limits.
  • Eliminate ignition sources from areas where flammable substances are handled or stored.  Ignition sources include electrical equipment, open flames, static electricity, and hot surfaces.
  • When heating flammable materials:
    • Never use an open flame.
    • Use heat sources such as steam baths, water baths, oil baths, heating mantles or hot air baths.
    • Never heat a closed container (even in a microwave).
  • Heat open containers only in a fume hood, with the sash pulled down completely.
  • When transferring flammable liquids from one container to another:
    • The preferred method is to transfer substances within a fume hood.
    • If transferring from one metal container to another metal container, ground both containers (to avoid static sparks).
    • Avoid transferring from one plastic container to another plastic container since they require special grounding techniques.
  • Before introducing flammable gases into a reaction vessel, the equipment should be purged either by evacuation or with an inert gas.


Organic Peroxides and Peroxide Forming Substances

Definition and Other Important Information
  • Hazard Communication Standard (29CFR 1910.1200):  
    • A liquid or solid organic chemical which contains the bivalent -0-0- structure and as such is considered a derivative of hydrogen peroxide, where one or both of the hydrogen atoms have been replaced by organic radicals.  Organic peroxides are thermally unstable chemicals, which may undergo exothermic self-accelerating decomposition.
    • GHS Hazard Categories, Signal Words, and Hazard Statements are summarized in this table.
    • Detailed descriptions are found in Appendix B of 1910.1200
  • Organic Peroxides are one of the more hazardous classes of chemicals commonly found in the laboratory.  Generally they are low-power explosives, but they are extremely sensitive to shock, sparks, and other forms of accidental ignition.
  • Organic Peroxides are highly flammable.
  • There are also many potentially hazardous compounds that auto-oxidize when exposed to air and form hydroperoxides and peroxides.  Some of the chemicals form peroxides that are violently explosive in concentrated solution or as solids, and therefore should never be evaporated to dryness.  Others are polymerizable unsaturated compounds and can initiate a runaway, explosive polymerization reaction.


Examples

The most commonly used peroxide-formers in use at St. Olaf are Tetrahydrofuran (THF) and Diethyl Ether.

Severe Peroxide Hazard with Exposure to Air (discard within 3 months of opening):

Organics
• Divinyl ether
• Divinyl acetylene (DVA)
• Isopropyl ether (Diisopropyl ether)
• Vinylidene chloride (1,1-dichloroethylene)
Inorganics
• Potassium amide
• Potassium metal
• Sodium amide (sodamide)


Peroxide Hazard on Concentration (Do not distill or evaporate without first testing for the presence of peroxides.  Discard or test for peroxides after 6 months):

• Acetal (acetaldehyde diethyl acetal)
• Acetaldehyde
• Benzyl alcohol
• 2-Butano
• Cumene ((isopropylbenzene)
• Cyclohexene
• Cyclohexanol
• 2-Cyclohexen-1-ol
• Cyclopentene
• Decahydronaphthalene (decalin)
• Dicyclopentadiene
• Diethyl ether (ether)
• Diethylene glycol dimethyl ether (Diglyme)
• Dioxane
• Ethylene glycol dimethyl ether (Glyme)
• Ethylene glycol ether acetates
• Ethylene glycol monoether
• Furan
• 4-Heptanol
• Methyl acetylene
• Methy isobutyl ketone
• 3-Methyl-1-butanol
• 3-Methyl-1-butanol
• Methyl cyclopentane
• 2-Pentanol
• 4-Pentene-1-ol
• 1-Phenylethanol
• 2-Phenylethanol
• 2-Propanol (isopropanol, IPA)
• Tetrahydrofuran (THF)
• Tetrahydronaphthalene (tetralin)
• Vinyl ethers
• Other secondary alcohols

 

Hazard of Rapid Polymerization Initiated by Internally-Formed Peroxides (Discard or test for peroxides within 6 months from opening)

• Acrylic acid
• Acrylonitrile
• Butadiene (Diacetylene)
• Chloroprene (2-chloro-1,3 butadiene)
• Chlorotrifluoroethylene
• Methyl methacrylate

• Styrene
• Tetrafluoroethylene
• Vinyl acetate
• Vinyl cetylene
• Vinyl chloride
• Vinyl pyridine


Standard Operating Procedures
  • Write the Date Opened on the jar.  Any jar found without such a date will be promptly processed for disposal.
  • Purchase and use only chemicals that contain peroxide-inhibitor additives (St. Olaf recognizes that there is a limited need for small quantities of ultra-pure chemicals that do not contain peroxide-inhibiting additives).
  • Purchase substances in small enough jar sizes that, when opened, will be used in less than 3 months.
  • Do not return unused chemicals to the original container.
  • All spills involving peroxides should be cleaned up immediately.  Solutions of peroxides can be absorbed on vermiculite or other absorbing material.
  • Inert solvents can be used to dilute peroxides, which reduces their sensitivity to shock and heat.  Do not use aromatic solvents.
  • Metal spatulas must not be used when handling peroxides.
  • Sources of heat are not allowed near peroxides.
  • Avoid forms of impact near peroxides.
  • Do not use chemicals that have reached their expiration date; take these substances to the Stockroom Manager for prompt stabilization and disposal.


Storage of Peroxide-Forming Chemicals
  • Store the containers in a tightly closed container.
  • Label containers with the “Flammable” and “Exploding Bomb” GHS pictograms.
  • Store in a flammables cabinet, away from light, heat, sources of ignition, oxidizers, and oxidizing acids.


Testing for Peroxides

(Use the test strips that are kept in the Chemistry Stockroom freezer; follow the directions)

  • Chemicals stored in the stockrooms and the Chemical Storage Facility will be tested by the Stockrooms Managers.
  • Laboratory Supervisors are responsible for testing for peroxides in their research laboratories.
  • For bottles with inhibiting agents added by the manufacturer:
    • Once a bottle is opened, it must be tested monthly for peroxides.
  • For bottles without inhibiting agents added by the manufacturer:
    • Once a bottle is opened, it must be tested every two weeks for peroxides.
  • Any jar found to have peroxide formation will have Hydroquinone or Butylated Hydroxy Toluene (BHT) added to the bottle (these are stabilizing agents), and monthly testing will continue.
  • The following concentration guidelines apply:
    • If peroxide levels are < 50 ppm, then the solution is still ok to use.
    • If peroxide levels are ≥ 50 ppm, then the solution will be stabilized and processed for disposal
  • Do not use the substance if there is any signs of crystal formation inside the jar; immediately inform the stockroom manager & CHO and do not move the jar.


Pyrophorics; Self-Heating; Emits Flammable Gases

Definition and Other Important Information
  • Pyrophorics.  A liquid or solid which, even in small quantities, is liable to ignite within five minutes after coming into contact with air.  Examples of pyrophorics include many finely divided metals, metal hydrides, alloys of reactive metals, low-valent metal salts and iron sulfides
  • Self-Heating.  A solid or liquid chemical, other than a pyrophoric, which, by reaction with air and without energy supply, is liable to self-heat; this chemical differs from a pyrophoric liquid or solid in that it will ignite only when in large amounts (kilograms) and after long periods of time (hours or days).
  • Chemicals, Which in Contact with Water, Emit Flammable Gases.  A solid or liquid chemical which, by interaction with water, is liable to become spontaneously flammable or to give off flammable gases in dangerous quantities.
    • Many of these substances have been traditionally referred to as “Water Reactives” (e.g., alkali metals, many organometallics, some hydrides, some anhydrous metal hydrides, nonmetal oxides and halides).  Typically these materials result in a large evolution of heat when in contact with water, decompose in moist air and may violently decompose in liquid water.


Examples


Standard Operating Procedures
  • Avoid contact with air or water; store in air-tight containers in a dark, cool, dry place.
  • Work in inert environments (pyrophorics).
  • Store pyrophorics in inert environments and away from flammables.
  • The Class D fire extinguisher (in Chemistry Stockroom Office) must be readily available.
  • Pyrophorics should be labeled, dated and inventoried when received.  The label should state:  DANGER! PYROPHORIC MATERIAL HIGHLY REACTIVE.


Self-Reactives

Definition and Other Important Information
  • Hazard Communication Standard (29CFR 1910.1200):  
    • Thermally unstable liquid or solid chemicals liable to undergo a strongly exothermic decomposition even without participation of oxygen (air).  This definition excludes chemicals classified under this section as explosives, organic peroxides, oxidizing liquids or oxidizing solids. A self-reactive chemical is regarded as possessing explosive properties when in laboratory testing the formulation is liable to detonate, to deflagrate rapidly or to show a violent effect when heated under confinement.
    • GHS Hazard Categories, Signal Words, and Hazard Statements are summarized in this table.
    • Detailed descriptions are found in Appendix B of 1910.1200