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Chemical Safety. Tim Wetzel Chemical Engineering December 10, 2009. Risk Assessment. Understand risks before performing experiments Know how to perform experiments Know chemical properties Know how to clean up spills Know emergency procedures Know risks to community. Risk Assessment.

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chemical safety

Chemical Safety

Tim Wetzel

Chemical Engineering

December 10, 2009

risk assessment
Risk Assessment
  • Understand risks before performing experiments
    • Know how to perform experiments
    • Know chemical properties
    • Know how to clean up spills
    • Know emergency procedures
    • Know risks to community
risk assessment1
Risk Assessment
  • Level of protection should be appropriate for a given risk
    • Basic safety protection significantly reduces probability of an accident without being too onerous
    • Use additional protection when necessary
routes of exposure
Routes of Exposure
  • Ingestion
    • No food or drink in the laboratory
    • No applying of makeup
    • Do not wear lab attire outside of lab
  • Inhalation
    • Experiments with hazardous substances performed in a fume hood
  • Adsorption
    • Wear appropriate gloves
    • Wear closed toed shoes
    • Wear lab coat
    • Wear Safety goggles
  • Injection
    • Use caution when handling sharp objects
general safety practices
General Safety Practices
  • Minimize amount of material
    • Just in time ordering
    • Several small bottles instead of large bottles
    • Use only minimum necessary for experiment
  • Use less hazardous chemical
  • Remove old chemicals
    • Chemicals older than 10 years are rarely necessary
safety attire
Safety Attire
  • Laboratory Attire
    • Safety glasses
    • Lab coat
    • Hair pulled back
    • Closed toed shoes
    • Legs covered
examples of hazards









Examples of Hazards

Glacial Acetic Acid

Sodium Hydroxide


Hydrofluoric Acid









msds information
MSDS Information
  • Material Safety Data Sheet
    • Physical Properties
    • Hazards
    • First Aid measures
    • Engineering controls
    • PPE
  • Must have a copy of MSDS for each chemical in the laboratory for easy access in an emergency
hazardous chemicals topics
Hazardous Chemicals Topics
  • Analyze risks and precautions for important hazardous chemicals
    • Flammables
    • Toxics
    • Corrosives
    • Compressed Gasses
flammable chemicals
Flammable Chemicals
  • Risk
    • Chemicals can ignite to produce laboratory fire
  • Prevention Techniques
    • Reduce concentration of vapors
    • Reduce ignition sources
    • Reduce amounts of substances outside of cabinets
    • Properly handle spills
fire triangle
Fire Triangle
  • Three necessary components
  • Eliminate one leg and fire will be extinguished
  • Only have flammables necessary for flammables in lab
  • Store excess flammables in cabinet
  • Close all bottles not in use
  • Typically oxygen in air
  • Reducing air contact kills fires
    • Fire blankets deprive fires of oxygen
    • Shut sash on fume hood fires
  • Ignition sources
    • Open flame
    • Static Electricity
    • Sparks
    • Hot plate
  • Pouring water cools fire
fume hoods
Fume Hoods
  • Manipulate flammables in fume hoods
    • Reduce vapor concentration
    • Controls ignition sources
    • Easier to handle fires
flammable storage
Flammable Storage
  • Store excess chemicals in flammable cabinet
  • Use approved refrigerator for cold flammables
  • No more than 10 L outside of cabinet
  • No more than 60 L in the entire lab
flammable spill
Flammable Spill
  • Small spill
    • Alert coworkers
    • Contain the spill
    • Prevent vapor emission
    • Remove ignition sources
    • Use non-flammable adsorbent material
  • Large spill
    • Alert coworkers
    • Remove ignition sources
    • Evacuate room
    • Call for assistance
toxic chemicals
Toxic Chemicals
  • Risk
    • Toxic chemicals react with tissue to produce serious or deadly effects
  • Prevention Techniques
    • Reduce amounts of toxic chemicals in laboratory
    • Hand chemicals in fume hood
    • Wear appropriate protection
    • Properly handle spills
toxic chemicals1
Toxic Chemicals
  • All chemicals are toxic, dose is important
  • “All things are poison, and nothing is without poison, only the dose permits something not to be poisonous”
    • Paracelsus
toxic chemicals2
Toxic Chemicals
  • Time horizons
    • Acute toxins produce reactions immediately (within 14 days) on contact with tissue
    • Chronic toxins have delayed response often manifested in months or years
      • Effect depends on exposure
      • Genetics
dose response
Dose Response
  • Dose has three components
    • Relative toxicity
    • Concentration
    • Exposure time
relative toxicity
Relative Toxicity
  • Usually animal studies with different routes of exposure
  • Often measured in concentration needed to kill 50% of population on a per mass basis
    • LD50, LC50
toxicity handling
Toxicity Handling
  • Follow prudent practices for prevention of chemical contact
    • Wear appropriate gloves, eye protection and clothing
    • Use fume hood or glove box to reduce concentration and as a secondary barrier
    • Decontaminate before doing non-laboratory activities
    • Minimize exposure time to chemical
    • Store according to chemical nature
toxic chemical spill
Toxic Chemical Spill
  • For highly toxic chemicals do not attempt to clean up any volume
    • Notify coworkers
    • Evacuate room and close doors
    • Call 911 or 67777
      • Give information on location, amount, chemical nature
    • Wait for emergency responders
corrosive chemicals
Corrosive Chemicals
  • Risk
    • Corrosive chemicals react with tissue
    • Corrosive chemicals react with metals
  • Prevention Techniques
    • Handle corrosives in fume hood
    • Wear appropriate protection
    • Neutralize spills
corrosive substances
Acids with pH <2



Acetic Acid

Bases with pH > 12.5



Corrosive Substances
corrosive chemicals1
Corrosive Chemicals
  • React with skin to cause burns and permanent tissue damage
    • Acids (not H2SO4) react to form protein barrier
    • Bases do not form protein barrier and can penetrate deep into the tissue
  • Corrosives can cause irreversible damage to eyes
corrosive protection
Corrosive Protection
  • PVC and nitrile gloves often provide appropriate protection
  • Use splash goggles
  • Use face shield if splashing is possible
corrosive compatibility
Corrosive Compatibility

Corrosive + Flammable = Fire

  • Corrosive + Toxin = Toxic gas
  • Corrosive + Metal = Hydrogen gas
  • Corrosive + Water = Violent reaction

Nitric Acid + Organic Solvent

corrosive adsorbents
Corrosive Adsorbents
  • Have appropriate spill clean up for corrosives in laboratory
  • Sodium bicarbonate is effective at neutralizing acids and bases
small corrosive spill
Small Corrosive Spill
  • Wear correct safety attire
  • Notify coworkers of spill
  • Contain spill to prevent spreading
  • Use suitable neutralizers to balance pH
  • Clean up the spill and properly dispose of contaminated materials
corrosive storage
Corrosive Storage
  • Acids and bases can be stored in same cabinet if secondary storage like plastic bins are used
compressed gasses
Compressed Gasses
  • Risk
    • Compressed gasses can act as missiles
    • Compressed gasses can be flammable, toxic, or other wise hazardous
    • Compressed gasses can displace air
  • Prevention Techniques
    • Properly store gasses
    • Use correct regulator
    • Use proper moving techniques
compressed gasses1
Compressed Gasses
  • Gasses can have enough kinetic energy to travel through concrete walls
compressed gas storage
Compressed Gas Storage
  • Valve cover must be on when not using gas
  • Cylinders must be upright and firmly attached
compressed gas handling
Compressed Gas Handling
  • Do not move a cylinder more than a foot without a cart
  • Firmly secured
  • No never move cylinder without having a valve cap
compressed gas storage1
Compressed Gas Storage
  • All cylinders must be secured even if they are empty
  • Separate accordingly to hazard class
    • Flammable
    • Oxidizer
    • Toxic
compressed gas regulators
Compressed Gas Regulators
  • Must use correct regulator
    • Dunning Hall
  • Regulator must be closed when not using tank
other important topics
Other Important topics
  • Highly reactive chemicals
  • Water sensitive compounds
  • Peroxide forming chemicals
  • Perchlorates
chemical storage
Chemical Storage
  • Prevent accidental reactions by storing chemicals accordingly to compatibilities
    • Flammables
      • Store in flammable cabinet
      • Do not store with corrosives or oxidizers
    • Corrosives
      • Separate acids and bases into secondary containers
toxic storage
Toxic Storage
  • Store according to chemical class
    • Flammable cabinet for toxic flammables
    • Corrosive cabinet for toxic acids and bases
  • If neither flammable nor corrosive, specify areas in the laboratory for storage of toxic chemicals
    • Store below eye level
chemical waste
Chemical Waste
  • Store chemical waste into compatibility classes
  • Keep containers closed when not in use
  • Label the concentrations and amount of every chemical
  • HSE Disposal collection at Thursday 10:30 to 11:30, 1PM to 2PM Macaulay Hall
  • Use yellow tags
  • Unknown chemical costs $350 to analyze
chemical waste accidents
Chemical Waste Accidents

Nitric Acid + Ethanol

chemical waste transport
Chemical Waste Transport
  • Use secondary containers such as plastic tubs
  • Use cart to transport large amounts of chemicals
  • Use freight elevators and avoid stairs
  • Avoid routes traveled by people
chemical safety conclusions
Chemical Safety Conclusions
  • Know the risk of chemicals
    • Know where to find specific risks
    • Know proper protective equipment for each risk
    • Know emergency procedures
    • Know compatibilities
    • Know correct disposal