the concentration range in which the. vapour of a compoun

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Chemical Safety for Civil Engineering

• David Bell CIH
• Health, Safety and Environment
• UBC
• April 29, 2004

http//www.civil.ubc.ca/home/safety/createmanual/i
ndex.html
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Types of Hazards

• Fire
• Reactive
• Toxic/Infectious
• Physical

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Solvent Fire Hazard Properties

• Vapour pressure
• Flash point
• Explosive limits
• Ignition Temperature

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Flammable Properties Definitions

• The explosive limits define
• the concentration range in which the
• vapour of a compound will flash in the
• presence of a spark or flame ignition
• source. Expressed as a percent. The ignition
  temperature is the temperature required to
  initiate combustion

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Flammable PropertiesFlash Point

• The flash point is the temperature at which the
  increased vapour pressure of a liquid results in
  a vapour concentration great enough to ignite
  (flash) in the presence of a spark or flame.
• A flammable liquid has a flash point less than
  37.8C.
• A combustible liquid has a flash point greater
  than, 37.8C.

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Corrosive Materials

• causes damage to skin and/or steel or aluminum
• corrosive injury may be an irritation or actual
  physical destruction of tissue membranes

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Corrosive Materials

• Acids
• hydrochloric sulfuric phosphoric
• nitric perchloric (oxidizing)
• acetic (organic)
• Bases (caustics)
• hydroxides (sodium potassium ammonium)
• amines anilines (organic)

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Corrosive Materials

• pH Chart
• 0 7 14
• 2.5 11.5
• acidic neutral basic
• corrosive corrosive

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Poisonous and Infectious Materials

• Causing serious and immediate effects
• Causing other toxic effects
• Biohazardous infectious

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Toxicity

• Dose
• Exposure concentration
• Duration of exposure
• Type of Exposure
• acute or single event
• chronic or repeated over time

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Delayed ToxicEffects

• Caused by long term exposure
• Carcinogenicity
• Exposure diseases (liver, kidney)
• Sensitization
• Dermatitis

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Regulatory Exposure Limits

• The time-weighted average (TWA) concentration
  that a worker may be exposed to for an 8-hour
  workday and a 40-hour work week, expressed in ppm
  or mg/m3
• This concentration is called the threshold limit
  value (TLV)

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Chemical HazardInformation Sources

• Workplace Hazardous Materials
• Information System (WHMIS)
• Labels
• Material Safety Data Sheets (MSDS)
• Education/Training

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WHMIS Hazard Classes

• Compressed Gas
• Flammable/Combustible
• Oxidizing
• Poisonous/Infectious
• Corrosive
• Dangerously Reactive

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Supplier Label Requirements

• Chemical Name
• Hazard Symbols
• Supplier Name
• Risk Phrase
• Precautions
• First Aid
• MSDS Reference

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ID
MSDS
Hazards
Symbols
Precautions
First Aid
Supplier Name
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Labels Created in Lab

• Required when
• Hazardous materials are decanted
• Original label damaged or lost
• Solutions prepared or developed in workplace
• Every container must have a label!

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Example of a Lab Label

• ACETONE
• Keep away from heat, sparks and flames.
• Avoid breathing vapours and protect eyes.
• Wear safety goggles and butyl rubber gloves.
• Use with local exhaust ventilation
• See Material Safety Data Sheet

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Laboratory Working Quantities

• Only a chemical name or identifier is required.
• No formulas, acronyms, foreign languages
• Remove, or completely cover old labels on reused
  containers

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Laboratory Samples

• Originating Outside the Lab require
• Material Identifier
• Supplier Identifier
• Chemical Information
• Emergency Phone Number
• Originating Within the Lab require
• An identifier (name, number or letter code)

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Material Safety Data Sheets (MSDS)

• Provides Information for
• risk assessments
• safe work procedures
• emergency procedures
• training
• first aid planning
• Available at worksite or on a data system

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MSDS Access

• Hard copy kept in Lab
• Internet Based Systems
• www.hse.ubc.ca
• Canadian Centre Occupational Health and Safety
  (www.ccohs.ca)

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Chemical Hazard Training

• Material-specific
• Detailed work procedures
• Precautions and Hazards
• PPE
• Emergency Procedures
• Done at work site

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Hazard Controls in theChemical Laboratory
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Hazard Controls

• Substitution, Minimization or Elimination
• Engineering controls
• Administrative Steps and Safety Procedures
  (Example No eating or drinking in lab)
• Personal Protective Equipment

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Fume Hoods

• Designed to control airborne exposures
• Effectiveness can be reduced by poor work
  practices.
• Minimum control air velocities specified by
  regulation. Must be checked annually.
• 0.5 m/sec for general use hoods
• 0.75 m/sec for carcinogen/radioisotope Hood

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Fume hood
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Fume Hood Air Flow
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Air FlowTurbulence

• Released smoke is captured in the breathing zone
  by downstream turbulence.

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Fume Hood Work Practices

• Use the hood!
• Wear PPE Required.
• Keep sash at labeled Height.
• Keep point of release 15 cm inside hood
• Label experiments
• No hazardous chemical storage

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Fume Hood Work Practices

• Keep head outside.
• Avoid cross drafts.
• No ignition sources.
• Dont block ventilation slots.
• Keep sash down when unattended.
• Keep bypass grill clean.

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Personal Protective Equipment

• Worn by workers for protection against various
  hazards.
• Eye Protection
• Gloves
• Protective Clothing
• Footwear
• Respiratory Protection

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Eye Protection

• Flying Particles
• Safety glasses
• with side shields
• Splash Protection
• Splash Goggles
• Face Shields
• Contact Lenses
• Chemical Irritation
• Full Face respirator

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Protective Footwear

• Slip, Crush, Temperature, Chemical, Puncture,
  Electrical, Uneven terrain
• Substantial, closed toe footwear required in labs
• Beach thongs, sandals or other open shoes are not
  permitted in laboratories, shops or active work
  areas.

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Protective Clothing

• Long Pants
• Lab Coat/Coveralls
• Aprons/sleeve guards
• Chemically resistant aprons or suits
• Face Shields

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Protective Gloves

• Physical, Temperature, Chemical and Electrical
  Hazards
• Match chemical resistance to materials in use
• No consensus standards for industry
• Follow manufacturers recommendations
• Web site http//www.bestglove.com/

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Respiratory Protection

• Nature of Hazard (Risk Assessment)
• Quantity
• Concentration
• Toxicity
• Gas or Particulate
• Odour Threshold
• Oxygen Levels

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Respiratory Protection

• Respirator types
• Disposable particulate ( N95)
• Cartridge particulate
• Chemical Cartridge
• Organic,
• Acid gases,
• Ammonia,
• Combination Types
• Air Line and Self Contained

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Respiratory ProtectionLimitations

• Facial fit testing
• Protection factors
• 5, 10 or 50 times the exposure limits
• Cartridge life
• Must be estimated to prevent breakthrough
• Website or consult with HSE
• Clean shaven
• Where respirator seals against skin

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Rules for use

• Nothing between the respirator and the face
• Inspect and pressure check before use
• Any smell in respirator or health symptoms leave
  area and investigate cause
• Use clear plastic bags to maintain cartridge life
  and keep face piece clean
• Wash after use

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Respiratory Protection

• Documented training is mandatory
• Everyone who wears a respirator must be training
  in its use and limitations and be fit tested
  annually.
• Selection, training and fit testing is available
  through HSE.

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Personal Protective Equip.

• Requires proper selection, training and
  supervision is ensure its effectiveness.
• Is used when elimination, engineering or
  administrative controls are not practicable.
• Must be administrated by knowledgeable persons.

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Summary

• Be aware of the hazards of the materials you are
  using.
• Use this knowledge to design safe work procedures
• Make use the all the hazard control methods
  (ventilation, PPE) to minimize risks