Chemical safety
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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

Hazard recognition nfpa

Hazard Recognition NFPA

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

Chemical safety


  • 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

Chemical safety


  • 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

Relative toxicity1

Relative Toxicity

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

Incorrect corrosive disposal

Incorrect Corrosive Disposal

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

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